Ask the Experts: Respiratory syncytial virus (RSV)

Results (57)

Respiratory syncytial virus (RSV) is a common respiratory virus, usually causing mild, cold-like symptoms, such as cough, runny nose, sore throat, headache, fatigue, and fever. Though most people recover in a few days, for some people, RSV can cause serious lower respiratory tract infection (LRTI), such as bronchiolitis or pneumonia. RSV is the most common cause of hospitalization in infants in the United States. Older adults, especially those with chronic health conditions and those age 75 and older, are also more likely to develop severe RSV disease and need hospitalization. There is no specific treatment for RSV illness, only supportive care.

RSV causes annual outbreaks of respiratory illness in people of all ages. In the continental United States, RSV typically circulates in the fall and winter months, between October and March, although its seasonality can vary locally from year to year.

Last reviewed: January 22, 2024

Most adults experience a mild upper respiratory tract infection with RSV, with symptoms lasting only a few days. Some adults with RSV develop lower respiratory tract disease, including pneumonia. Because public health surveillance and testing for RSV in adults been limited in the past, our estimates of the burden of RSV disease are not precise and may underestimate the true burden among adults. Among U.S. adults age 65 and older, RSV is responsible for approximately 60,000 to 160,000 hospitalizations and 6,000 to 10,000 deaths each year.

Older adults at highest risk for severe RSV infection generally have one or more chronic medical conditions, including:

  • lung diseases (including chronic obstructive pulmonary disease [COPD] and asthma)
  • cardiovascular diseases (such as congestive heart failure and coronary artery disease)
  • moderate or severe immune compromise (whether caused by disease or by treatment with an immunosuppressive medication)
  • diabetes mellitus
  • neurologic or neuromuscular conditions
  • kidney disorders
  • liver disorders
  • hematologic disorders

Other factors associated with increased risk include:

  • frailty
  • advanced age (hospitalization rates are highest among those age 75 or older)
  • residence in a nursing home or other long-term care facility

In addition to these listed factors, individual patients may have other underlying factors that a health-care provider determines might increase the risk for severe respiratory disease.

Last reviewed: January 22, 2024

Almost all U.S. infants and toddlers contract RSV illness within the first two years of life. RSV causes a mild respiratory illness in most, with symptoms including cough, runny nose, fever, and fatigue. Illness is more likely to be mild if the child is older at the time of first infection. Infants with RSV infection frequently develop bronchiolitis, a lower respiratory tract disease (LRTD) that can be severe.

RSV LRTD is the leading cause of hospitalization among U.S. infants, who may require supplemental oxygen, treatment for dehydration, or mechanical ventilation. Approximately 50,000–80,000 RSV-associated hospitalizations and 100–300 RSV-associated deaths occur each year among U.S. infants and children younger than age 5 years. The risk of severe RSV disease is increased by prematurity and lung disease, among other health conditions. However, RSV is also the leading cause of hospitalization among healthy, full-term infants. The large majority (almost 80%) of infants and children younger than age 2 who are hospitalized with RSV are otherwise healthy and have no underlying medical conditions.

Some otherwise healthy American Indian or Alaska Native (AI/AN) children experience higher rates of severe RSV disease than the general population. One study found that the incidence of RSV-associated hospitalization among children in their second RSV season in some AI/AN communities was 4 to 10 times higher than that of similar-aged children elsewhere in the United States. AI/AN children living in remote areas also may have difficulty accessing adequate medical care when they develop LRTD.

Last reviewed: January 22, 2024

In most temperate regions of the continental United States and other areas with similar climates, RSV season typically begins in the fall and peaks in the winter, generally circulating between October and the end of March. However, the timing and severity of RSV season in a given community can vary from year to year. RSV seasonality was temporarily disrupted by the COVID-19 pandemic and widespread changes in social interactions and infection control practices (e.g., mask wearing, social distancing).

U.S. states and territories with very different weather patterns from the continental United States (e.g., Alaska, and areas with tropical weather patterns, such as Hawaii, southern Florida, Puerto Rico, and other island territories) may experience very different patterns of local RSV circulation. For this reason, public health and healthcare authorities in those areas may issue different recommendations for appropriate timing of RSV prevention strategies (vaccines, monoclonal antibodies).

Last reviewed: January 22, 2024

In May 2023, FDA licensed two RSV vaccines: RSVPreF3 (Arexvy, GSK) and RSVpreF (Abrysvo, Pfizer). They are both licensed for the prevention of RSV-associated lower respiratory tract disease (LRTD) in adults 60 age years and older in the United States. Only Abrysvo is licensed for use during pregnancy (during 32 through 36 weeks and 6 days’ gestation) for the prevention of RSV disease in infants. Both vaccines are recombinant protein vaccines that contain the prefusion form of a spike protein on the surface of the RSV virus. Because these vaccines contain only a piece of the virus, they cannot cause RSV illness.

The GSK RSVPreF3 vaccine, Arexvy, includes an AS01adjuvant, a chemical designed to enhance the immune response to vaccination. AS01 is the same adjuvant used in GSK’s recombinant zoster vaccine (Shingrix), but Arexvy contains half the amount of adjuvant as a dose of Shingrix. Pfizer’s vaccine does not contain an adjuvant.

For further information about both vaccines, the package inserts are available from FDA: Package Insert – AREXVY (fda.gov) and Package Insert – ABRYSVO (fda.gov).

Last reviewed: January 22, 2024

Both RSVPreF3 (Arexvy, GSK) and RSVpreF (Abrysvo, Pfizer) vaccines were effective in preventing RSV-associated lower respiratory tract disease (LRTD) in clinical trial participants, over the course of two RSV seasons.

The global clinical trials for RSVPreF3 (Arexvy, GSK) vaccine involved nearly 25,000 participants and some participants were followed for 2 RSV seasons. One dose had an efficacy of 82.6% during the first RSV season and 56.1% during the second season in preventing symptomatic, laboratory-confirmed RSV-associated LRTD.

The RSVpreF (Abrysvo, Pfizer) vaccine global clinical trials involved nearly 37,000 participants, and some participants were followed for 2 RSV seasons. Efficacy of 1 dose in preventing symptomatic, laboratory-confirmed RSV-associated LRTD was 88.9% during the first RSV season and 78.6% during a partial second season.

Few people enrolled in the clinical trials were either frail or of advanced age (80 or older), and none lived in long-term care facilities. People with immunocompromising conditions were excluded from clinical trials. For this reason, the clinical trials did not measure how well the vaccines would work in the people at highest risk of serious RSV disease.

Last reviewed: January 22, 2024

Currently, protection from serious lower respiratory tract disease (LRTD) after RSV vaccination is expected to last for about two RSV seasons. In clinical trials, the efficacy of the vaccine was tested in some people over 2 RSV seasons, and both vaccines provided significant protection in the second season. RSV vaccination is currently recommended as a single dose. ACIP will update its recommendations as more data become available over time concerning the durability of protection from a single dose and the effectiveness of revaccination.

Last reviewed: January 22, 2024

Both RSV vaccines are currently licensed and recommended as a one-time dose for any person; data are not available at this time to make recommendations for revaccination. At this time, a pregnant person who receives Abrysvo during one pregnancy is not recommended to receive Abrysvo during a subsequent pregnancy. ACIP will make decisions concerning revaccination as more data become available.

Last reviewed: January 22, 2024

No. Only the RSVpreF vaccine, Abrysvo by Pfizer, is licensed and recommended for use between 32 weeks and 36 weeks 6 days of gestation to prevent RSV-associated lower respiratory tract disease in infants younger than 6 months old. Do not use Arexvy (GSK) during pregnancy.

Last reviewed: January 22, 2024

ACIP recommends use of either RSVpreF (Abrysvo, Pfizer) or RSVPreF3 (Arexvy, GSK) as a single dose in adults age 60 years and older, using shared clinical decision-making (SCDM). In SCDM-type recommendations, the choice to vaccinate is an option guided by a patient’s individual risk for severe disease and the patient’s values and preferences. SCDM also takes into account the provider’s clinical discretion concerning the patient and the vaccine.

ACIP recommends the following factors be considered during the shared clinical decision-making process: whether the patient has one or more risk factors for severe RSV disease; a patient’s risk of exposure to RSV (e.g., are they around young children, or living in a long-term care facility?); a patient’s preferences for RSV vaccination, including an understanding of safety, side effects, and costs; and the clinical discretion of the health-care provider.

The risk of hospitalization with RSV disease rises with increasing age after age 60. Other factors that increase risk are overall frailty, residence in a long-term care facility or nursing home, and one or more chronic medical conditions. A separate question provides details on risk factors.

CDC has developed a simple job aid for providers to assist in these discussions: www.cdc.gov/vaccines/vpd/rsv/downloads/provider-job-aid-for-older-adults-508.pdf.

See the full 2023 ACIP recommendation for older adults here: www.cdc.gov/mmwr/volumes/72/wr/mm7229a4.htm.

Last reviewed: January 22, 2024

The following conditions and factors place some older adults at the highest risk for severe RSV infection:

  • chronic medical conditions such as lung diseases (including chronic obstructive pulmonary disease and asthma)
  • cardiovascular diseases (such as congestive heart failure and coronary artery disease)
  • moderate or severe immune compromise (either due to an immunocompromising disease or treatment with an immunosuppressing treatment)
  • diabetes mellitus
  • neurologic or neuromuscular conditions
  • kidney disorders
  • liver disorders
  • hematologic disorders

Other factors associated with increased risk include:

  • overall frailty
  • advanced age
  • residence in a nursing home or other long-term care facility
  • other underlying factors that a health care provider determines might increase the risk for severe respiratory disease
Last reviewed: January 22, 2024

A shared clinical decision-making (SCDM) recommendation is different from routine vaccine recommendations based simply on a person’s age or risk for disease. With routine vaccine recommendations the default decision is to vaccinate all persons in a specified age group or risk group. With SCDM recommendations, vaccination is not the default decision based on age or risk group alone: desirability will vary from person to person.

In the case of RSV vaccine, SCDM recommendations are informed by:

  • whether the patient has any risk factors for severe RSV disease,
  • the safety profile of the RSV vaccine products and the patient’s risk tolerance,
  • a patient’s preferences for prevention of RSV, and
  • the clinical discretion of the health care provider

In the judgment of ACIP members, both vaccines were well tolerated, and the safety profiles were generally acceptable. Six cases of inflammatory neurologic events were reported (including Guillain Barré syndrome and others) after RSV vaccination during clinical trials of the two licensed vaccines, but evidence was insufficient to determine whether these were due to chance or possibly caused by vaccine. Investigations continue into these findings and safety monitoring is ongoing to clarify whether or not there is any increased risk of these conditions associated with RSV vaccination. The ACIP SCDM recommendation is intended to provide flexibility for providers and vaccine recipients to take into account an individual’s risks for severe RSV disease and patient preference. Some will choose to defer vaccination until more is known about the vaccine’s performance or until their personal risk for severe RSV is greater.

CDC has a one-page resource for healthcare providers to assist in these SCDM conversations with patients: www.cdc.gov/vaccines/vpd/rsv/downloads/provider-job-aid-for-older-adults-508.pdf.

Last reviewed: January 22, 2024

Document the discussion and reason for deferral in the medical record. Because the risk of severe disease increases with age, plan to revisit the decision periodically to vaccinate once the patient’s risk-benefit assessment shifts in favor of vaccination.

Last reviewed: January 22, 2024

No. Only a single dose of RSV vaccine is currently approved and recommended at this time. There is no evidence at this time to determine whether revaccination would be of value. As data become available, FDA and the ACIP will evaluate the benefit of revaccination.

Last reviewed: January 22, 2024

Pregnant people between 32 and 36 weeks and 6 days’ gestation during the months of September through January in the United States should get one dose of the Pfizer RSVpreF vaccine (Abrysvo) to protect their babies during their first RSV season after birth. Only Abrysvo is FDA-approved and recommended for pregnant people. Arexvy (by GSK) is not approved and should not be given during pregnancy.

In most of the continental United States, maternal RSV vaccine is recommended only September through January. Those who provide health care to pregnant people who live in areas with different patterns of RSV seasonality, such as Alaska, Hawaii, parts of Florida, or other jurisdictions outside the continental United States, should follow guidance from local or regional public health authorities about the timing of RSV vaccination during pregnancy in their regions.

Last reviewed: January 22, 2024

No. Only the Pfizer (Abrysvo) RSV vaccine is recommended for pregnant people. The GSK RSV vaccine (Arexvy) is not licensed or recommended for use in pregnancy.

If Arexvy is inadvertently administered during pregnancy, do NOT administer a dose of Abrysvo. Instead, CDC recommends that the infant (if younger than 8 months) should receive nirsevimab during RSV season (October through March in most of the continental United States). Treat the infant in the same manner as an infant born to a mother who did not receive RSV vaccination during pregnancy.

CDC strongly urges that this type of administration error be reported to the Vaccine Adverse Event Reporting System, VAERS (https://vaers.hhs.gov). Prevent administration errors with health care provider training on the different indications for each RSV prevention product (both vaccines and the nirsevimab preventive antibody for infants), and always check product labels at least three times before administration to verify that the correct product is being administered to the patient. Consider implementing other feasible safeguards in your system (e.g., electronic alerts) to prevent such errors.

For additional information about this type of error, see the CDC Clinician Outreach and Communication Activity (COCA) Now update from January 22, 2024:  https://emergency.cdc.gov/newsletters/coca/2024/012224.html

Last reviewed: January 22, 2024

No. RSV vaccination during pregnancy is only recommended for pregnant people who are at the recommended stage of pregnancy (32 weeks through 36 weeks 6 days’ gestation) during the recommended time of year (typically September through January). In regions with seasonal patterns of RSV that differ from the continental United States, such as Alaska, Hawaii, or subtropical parts of Florida, follow local public health or health care guidance on timing, which may differ.

Last reviewed: January 22, 2024

Yes. Pfizer’s RSV vaccine (Abrysvo) may be administered from 32 weeks through 36 weeks and 6 days’ gestation. RSV vaccine should not be administered to someone at 37 weeks’ gestation or beyond.

RSV vaccine should be administered at least 2 weeks before delivery to allow time for the maternal immune system to create antibodies and transfer sufficient antibodies to the fetus for adequate protection after birth. If the gestational age is appropriate, but clinical judgment is that delivery is likely to occur within 2 weeks, it is reasonable to defer vaccination and plan to administer nirsevimab RSV preventive antibody to the infant after delivery. Infants born less than 14 days after maternal RSV vaccination are recommended to receive nirsevimab RSV preventive antibody after birth to ensure adequate protection.

Last reviewed: January 22, 2024

Many pregnant people will have a choice about whether to get Abrysvo during pregnancy or to give nirsevimab to their infant after birth. Those who are between 32 and 36 weeks 6 days’ gestation between September and January, may be vaccinated with Abrysvo or have their infant receive nirsevimab soon after birth (preferably within the first week of life if born during a month when nirsevimab administration is recommended).

It is important to note that both Abrysvo RSV vaccine and nirsevimab products may not be available to all people in all settings. In some facilities or circumstances, only one option might be available: those offered Abrysvo during pregnancy may not wish to defer that option unless they are confident that nirsevimab will be available for their infant. All infants up to 8 months 0 days of age whose mothers were not vaccinated may be given nirsevimab when feasible, before or during their first RSV season.

Last reviewed: January 22, 2024

Yes. VFC-eligible pregnant adolescents younger than age 19 may receive VFC-funded Abrysvo during pregnancy, if indicated, in VFC-participating facilities. Contact your state immunization program with questions about VFC and Abrysvo.

Last reviewed: January 22, 2024

Both RSV vaccines (Arexvy, Abrysvo) are administered by the intramuscular route.

Last reviewed: January 22, 2024

Yes. It is acceptable to administer either RSV vaccine at the same time as other recommended vaccines, in accordance with CDC’s general best practice guidelines for immunization. This is especially important if you are concerned an unvaccinated patient will not return or if the patient’s immediate risk is high (such as when seasonal influenza, RSV, and COVID-19 are circulating). Coadministration might increase short-term side effects (greater reactogenicity), such as fever, soreness, body aches, or headache, especially when administering more than one vaccine containing a non-aluminum adjuvant designed to enhance the immune response. While these side effects are not unsafe, they may be unpleasant for a day or two. If you are confident that a patient will return, the patient may prefer to separate the administration of vaccines that are less time-sensitive (e.g., shingles vaccine) to reduce the likelihood of uncomfortable side effects. There is no specific minimum interval between non-live vaccines, so separation by just a few days is acceptable, if desired.

Last reviewed: January 22, 2024

The safety and effectiveness of RSV vaccines have not been studied in infants. The family should be informed of the error, and nirsevimab should be administered as recommended as soon as feasible. CDC experts recommend that if you administer nirsevimab within 72 hours of the error, and you know where the RSV vaccine was injected, you should administer the nirsevimab in a different anatomic site. Facilities that stock RSV vaccine and nirsevimab should put systems and procedures in place to prevent this type of error, including staff training, clear labeling, and warnings in storage units. This medication error and any suspected adverse events following the error should be reported to the Vaccine Adverse Event Reporting System (VAERS) at https://vaers.hhs.gov.

For additional information about this type of error, see CDC’s COCA Now: Clinician Outreach Communication Activity update, dated January 22, 2024, at https://emergency.cdc.gov/newsletters/coca/2024/012224.html.

CDC has developed a job aid to help clinical staff reduce the risk of administration errors related to RSV vaccines and nirsevimab:
• Only Administer Nirsevimab (Beyfortus, Sanofi) to Young Children (www.cdc.gov/vaccines/vpd/rsv/downloads/rsv-error-prevention-children.pdf)

Last reviewed: February 5, 2024

Vaccination involves active immunization, where an antigen is administered to a recipient to activate the recipient’s immune system and generate an immune response (which includes developing antibodies). Active immunization may require up to 2 weeks to have its full protective effect, and sometimes a series of vaccinations is required. Protection may last for months or be life-long, depending upon the type of immune response triggered. The effectiveness of a vaccine depends on the recipient’s immune system.

Nirsevimab (Beyfortus, Sanofi) is an injectable, long-acting monoclonal antibody product that gives the recipient direct, immediate protection through passive immunization. The antibodies of nirsevimab circulate in the bloodstream and recognize and attach to the RSV virus if encountered, leading to elimination of the virus. These antibodies protect the patient for at least 5 months until they gradually break down and disappear. The highest risk of severe RSV infection and hospitalization for children is during their first RSV season as an infant. Nirsevimab will not prevent children from getting RSV infections in future seasons, but the general risk of hospitalization due to RSV in childhood is far lower after infancy.

Last reviewed: January 22, 2024

Clinical trials of nirsevimab in infants less than 8 months old born during or entering their first RSV season showed that giving nirsevimab reduced the risk of RSV-associated lower respiratory tract infection (LRTI) requiring a medical visit or hospitalization by approximately 80 percent and reduced the risk of ICU admission for this reason by 90 percent.

Clinical trials did not study hospitalization rates among older infants and toddlers at high risk of severe RSV disease in their second RSV season. Instead, a study was done to measure blood levels of nirsevimab given to infants and toddlers at increased risk for severe RSV disease (certain preterm infants and those with serious heart or lung disease). The blood levels of nirsevimab were equivalent to the levels in healthy infants in the clinical trial who received nirsevimab in their first RSV season. Based on this finding, it is estimated that their protection from serious infection would also be similar.

Last reviewed: January 22, 2024

The nirsevimab clinical trials demonstrated effective protection lasted at least 5 months (150 days) in preventing severe RSV disease (disease requiring medical attention, hospitalization or ICU admission). Protection may persist longer than 5 months, but this was the period of time studied in the trials.

Last reviewed: January 22, 2024

Yes, it is. Infants and toddlers eligible for the VFC program may receive nirsevimab when recommended in the same way and in the same facilities where they receive VFC vaccines. Providers who participate in VFC should follow all VFC requirements for ordering, storage, and administration established by their state immunization program.

Last reviewed: January 22, 2024

ACIP recommends one dose of nirsevimab (Beyfortus, Sanofi) preventive antibody for all infants less than 8 months and 0 days of age who are born during or entering their first RSV season.

ACIP also recommends one dose of nirsevimab for specific groups of infants and children age 8 through 19 months who are entering their second RSV season and at increased risk for severe RSV disease.

Children 8 through 19 months at high risk and ineligible for palivizumab:

  • American Indian or Alaskan Native children entering their second RSV season. This is especially important for those who are in remote regions or in communities known to have increased rates of severe RSV disease in children.

Children age 8 through 19 months at high risk and eligible for palivizumab (Synagis, AstraZeneca):

  • Children with chronic lung disease of prematurity who require medical support during the six months before the start of their second RSV season
  • Children who are severely immunocompromised
  • Children with evidence of severe cystic fibrosis (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable) or that have weight-for-length that is less than the 10th percentile

If nirsevimab is given to a child eligible for palivizumab, do not give palivizumab. If nirsevimab is unavailable, CDC recommends that palivizumab (a short-acting RSV monoclonal antibody) should be administered per AAP recommendations (see https://doi.org/10.1542/peds.2023-061803). Because palivizumab is effective for 30 days, if nirsevimab becomes available during the RSV season, do not administer nirsevimab within 30 days of a dose of palivizumab. Do not give palivizumab during the season after administering nirsevimab.

The full ACIP recommendation is available at www.cdc.gov/mmwr/volumes/72/wr/pdfs/mm7234a4-H.pdf.

Last reviewed: January 22, 2024

Infants and children 8 months through 19 months of age who meet one or more of the criteria listed below are recommended to receive one dose of nirsevimab (200 mg, administered as two 100-mg MFS injections given at the same time at different injection sites) just before or during their second RSV season:

  • Children with chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the second RSV season
  • Children with severe immunocompromise
  • Children with cystic fibrosis who have either 1) manifestations of severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable), or 2) weight-for-length less than the 10th percentile
  • American Indian or Alaska Native (AI/AN) children

Nirsevimab is particularly important for AI/AN children who live in remote regions, where access to medical care may be challenging, or in areas where there are known high rates of severe disease among older infants and toddlers.

Last reviewed: January 22, 2024

The optimal timing for nirsevimab to be administered is shortly before the RSV season begins; however, nirsevimab may be administered to eligible infants and children who have not yet received a dose at any time during the season.

Nirsevimab should be administered to infants less than 8 months old and infants and children 8 through 19 months old during the months of October through March in most areas in the United States, unless otherwise advised by public health authorities. Adjustment of timing due to RSV activity outside this typical timeframe is most likely to be necessary in more tropical climates and in Alaska.

Last reviewed: January 22, 2024

Some American Indian or Alaska Native (AI/AN) children experience higher rates of severe RSV disease than the general population. A recent study found that the incidence of hospitalization due to RSV among some AI/AN children in their second year of life was four to ten times higher than that of similar-aged children in multiple study sites in the United States. Also, some AI/AN communities live in remote regions, making transportation of children with severe RSV to obtain medical care more challenging. Although the available data are limited and may not apply to all AI/AN children in all settings, ACIP recommends nirsevimab for AI/AN children entering their second RSV season.

Last reviewed: January 22, 2024

Palivizumab (Synagis, AstraZeneca) is another injectable monoclonal antibody recommended by the American Academy of Pediatrics (AAP) for use in certain infants and children with underlying medical conditions that put them at high risk of severe RSV infection. It is not long-acting and must be administered once monthly, up to 5 doses, through the RSV season. The cost of palivizumab is much higher than the cost of nirsevimab. Nirsevimab should be used for children eligible for either product.

Once a single dose of nirsevimab is given for the season, palivizumab is not needed for that season. In circumstances where nirsevimab is unavailable, a high-risk infant or toddler who is also eligible for palivizumab should receive palivizumab. If palivizumab is administered initially during a season and nirsevimab becomes available before 5 monthly doses of palivizumab have been given, discontinue palivizumab and administer one dose of nirsevimab (at least a month after the most recent dose of palivizumab).

AAP recommendations for use of palivizumab and nirsevimab are found at: https://publications.aap.org/redbook/resources/25379 and https://publications.aap.org/pediatrics/article/152/1/e2023061803/192153/Palivizumab-Prophylaxis-in-Infants-and-Young.

Last reviewed: January 22, 2024

If you are unable to obtain prenatal records or verify receipt of maternal RSV vaccine, CDC recommends that the baby receive nirsevimab, particularly if it is shortly before or during the RSV season. Don’t forget to check the state immunization information system (IIS) for the mother’s vaccination record. It is also important to attempt to verify from the birthing facility records whether this baby received nirsevimab prior to discharge to avoid giving a second dose.

Last reviewed: January 22, 2024

Yes. Infants born less than 14 days after the mother received RSV vaccine should receive nirsevimab. Infants born within 14 days after maternal vaccination may not have had sufficient time in utero to receive adequate protection from maternal RSV antibodies produced after vaccination. Infants born 14 days or more after maternal vaccination are not recommended to receive nirsevimab.

Last reviewed: January 22, 2024

In rare circumstances, nirsevimab may be considered for infants in their first RSV season who were born to RSV-vaccinated mothers. These situations may include:

  • infants born to mothers who have health conditions that might prevent an adequate maternal immune response to vaccination (an immunocompromising condition caused by disease or immunosuppressive treatment)
  • infants whose mothers have conditions associated with reduced transplacental antibody transfer (such as a mother living with HIV infection)
  • infants who might have lost maternal antibodies, such as those who have undergone cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO)
  • infants with substantially increased risk for severe RSV disease (such as hemodynamically significant congenital heart disease or intensive care admission requiring oxygen at hospital discharge).

Infants and children age 8–19 months who are at increased risk for severe RSV disease and are entering their second RSV season are recommended to receive nirsevimab regardless of history of maternal vaccination.

Last reviewed: January 22, 2024

Nirsevimab dosing is based upon weight and/or age. It is available in 50-mg or 100-mg manufacturer-filled syringes (MFS). Infants younger than 8 months and weighing less than 5 kgs (11 lbs.) should receive a 50-mg dose, given as a 50-mg MFS. Infants younger than 8 months and weighing 5 kg (11 lb.), or more, should receive a single 100-mg dose, given as a 100-mg MFS. Infants and toddlers age 8 months through 19 months who need nirsevimab should receive a 200-mg dose, given as two 100-mg MFS.

Do not administer two 50-mg MFS to an infant who needs a 100-mg MFS. The supply of 50-mg MFS is intended for the smallest infants. The cost of the 50-mg and 100-mg MFS are equivalent, despite the difference in dose; insurance plans may not cover the cost of two doses given to an infant not recommended to receive two doses. Only high-risk children age 8 through 19 months are recommended to receive two (100-mg) MFS doses at the same visit.

See the Immunize.org standing order template for details: www.immunize.org/wp-content/uploads/catg.d/p3097.pdf.

Last reviewed: January 22, 2024

The supply of 50-mg manufacturer-filled syringes (MFS) should be reserved for infants weighing less than 5 kilograms (less than 11 pounds). In addition, insurers may not cover the cost of two 50-mg MFS doses administered to one infant. The cost of a single MFS is the same, whether it is a 50-mg MFS or a 100-mg MFS. Only high-risk children age 8 through 19 months are recommended to receive two (100-mg) MFS doses at the same visit.

Last reviewed: January 22, 2024

Yes, nirsevimab may be coadministered with all other recommended age-appropriate vaccines. Nirsevimab should not interfere with the immune response to routine childhood vaccines when given together or at any time before or after them. Likewise, vaccination does not interfere with the effectiveness of nirsevimab.

When giving several injections at a single visit, separate intramuscular vaccines by at least 1 inch in the body of the muscle, if possible, to reduce the likelihood of overlapping local injection site reactions.

Last reviewed: January 22, 2024

No, these two antibody preparations should not interfere with each other. Administer nirsevimab as recommended.

Last reviewed: January 22, 2024

Nirsevimab comes in a prefilled syringe. In most states, anyone who can administer injections can administer nirsevimab. If you have questions about a specific type of healthcare worker, check the scope of practice rules in your state.

Last reviewed: January 22, 2024

Only infants younger than age 8 months 0 days are routinely recommended to receive nirsevimab during or before their first RSV season. The recommended use of nirsevimab in older infants and toddlers age 8 months through 19 months is narrowly limited to American Indian/Alaskan Native children and children with specific conditions that put them at high risk of severe lower respiratory tract disease due to RSV.

Last reviewed: January 22, 2024

The recipient should be informed of the error, and RSV vaccine should be administered as recommended. A 50-mg or 100-mg MFS dose of antibody is very small compared to the body weight of an adult and you should not assume the dose would have any protective effect. There is no defined waiting period after antibody administration for vaccine administration. Facilities that stock RSV vaccine and nirsevimab should put systems and procedures in place to prevent this type of error, including staff training and clear labeling and warnings in storage units.

CDC strongly encourages reporting of this medication error and any suspected adverse events following the error to the Vaccine Adverse Event Reporting System (VAERS) at https://vaers.hhs.gov if the antibody was administered at the same visit as vaccines. If antibody was administered alone, report the incident to MedWatch online (www.fda.gov/medwatch), by fax, by mail, or by contacting FDA at 1-800-FDA-1088.

CDC has developed a job aid to help clinical staff reduce the risk of administration errors related to RSV vaccines and nirsevimab:
• Only Administer Nirsevimab (Beyfortus, Sanofi) to Young Children (www.cdc.gov/vaccines/vpd/rsv/downloads/rsv-error-prevention-children.pdf)

Last reviewed: February 5, 2024

Optimally, vaccination of eligible adults should occur before the onset of increased RSV activity in the community. The timing of the onset, peak, and decline of RSV activity varies from one year to the next; however, because the vaccine’s protection in older adults lasts at least 2 seasons, if you have the opportunity to vaccinate during the summer, you might choose to give it if you are concerned that you may not have the opportunity later in the fall.

Last reviewed: January 22, 2024

Aim for nirsevimab administration in the first week of life for infants born shortly before or during the RSV season (typically October through March). Infants with prolonged birth hospitalizations due to prematurity or other causes should receive nirsevimab shortly before or promptly after discharge.

Infants younger than age 8 months born outside of the RSV season and older infants or toddlers at high risk who are recommended to receive nirsevimab in their second RSV season, should aim to receive nirsevimab shortly before the start of the RSV season (typically October).

If the ideal timing is missed, age-eligible infants and children who have not yet received a dose may be immunized at any time during the RSV season.

Last reviewed: January 22, 2024

CDC has published an immunization information statement (IIS) for nirsevimab that is the equivalent of the vaccine information statement (VIS) for vaccines. Just as with a VIS, providers should give the IIS to the parent or caregiver before immunization and document it in the medical record.

Access the current nirsevimab IIS and translations in at least 24 languages from Immunize.org at: www.immunize.org/vaccines/vis/iis-rsv/.

Last reviewed: January 22, 2024

Yes, you should report administration of nirsevimab to your state immunization information system (IIS, or “registry”) as you would report vaccine administration. Contact your state immunization program if you have specific questions about reporting to your state immunization information system.

Last reviewed: January 22, 2024

It is important that all healthcare providers, both prenatal and pediatric, ensure that maternal RSV vaccination status is clearly documented and communicated. Prenatal care providers and birthing hospitals should ensure maternal RSV vaccination is reported to state immunization information systems (registries) and documented in maternal and newborn health records. It is also important to provide the pregnant person with a personal record of immunization.

Failure to document and communicate maternal RSV vaccination may result in extra work for pediatric offices and families to obtain records or in unnecessary administration of nirsevimab, at a retail cost of approximately $450 per dose.

Last reviewed: January 22, 2024

In clinical trials of both licensed and recommended RSV vaccines, GSK and Pfizer, mild, local injection site reactions (redness, swelling), fatigue, muscle aches and headache were noted.

Last reviewed: January 22, 2024

In the clinical trials of both RSVPreF3 (Arexvy) and RSVpreF (Abrysvo) vaccines, a small number of inflammatory neurologic events, including GBS, were reported after RSV vaccination. Whether these events occurred due to chance or whether RSV vaccination might increase the risk for inflammatory neurologic events is not yet known. CDC is actively monitoring the safety of these vaccines through national safety surveillance systems in order to detect any risk too small to be detected in the clinical trials.

Last reviewed: January 22, 2024

In clinical trials, the vast majority of infants had no side effects detected after nirsevimab administration. The most common side effects noted during the clinical trials of nirsevimab were rash occurring within 2 weeks after injection (seen in 0.9% of nirsevimab recipients versus 0.6% of placebo recipients) and injection site reactions (including redness, pain, swelling) occurring within 7 days after injection (0.3% of nirsevimab recipients versus 0% of placebo recipients). See the product package insert for more details: www.accessdata.fda.gov/drugsatfda_docs/label/2023/761328s000lbl.pdf.

Last reviewed: January 22, 2024

Adverse reactions occurring after administration of nirsevimab alone should be reported to MedWatch online (www.fda.gov/medwatch), by fax, by mail, or by contacting FDA at 1-800-FDA-1088.

Adverse reactions occurring after the coadministration of nirsevimab with a vaccine should be reported to the Vaccine Adverse Event Reporting System (VAERS) https://vaers.hhs.gov, and reports should specify that the patient received nirsevimab on the VAERS form.

Last reviewed: January 22, 2024

Yes. V-safe is a vaccine safety monitoring system that lets recipients of certain new vaccines share with CDC how they feel after vaccination by receiving and responding to a series of periodic text messages. This is a voluntary system and individual recipients must register to participate V-safe. V-safe is available to all RSV vaccine recipients but is not being used for nirsevimab preventive antibody. For information, or to register, visit CDC’s V-safe website at: www.cdc.gov/vaccinesafety/ensuringsafety/monitoring/v-safe/index.html.

Last reviewed: January 22, 2024

Nirsevimab is contraindicated in persons with a history of severe allergic reactions (e.g., anaphylaxis) after a previous dose or to a product component. As with any injection, when administering nirsevimab to children with increased risk for bleeding, providers should follow ACIP’s general best practice guidelines for immunization.

Last reviewed: January 22, 2024

RSV vaccines are contraindicated for and should not be administered to persons with a history of severe allergic reaction, such as anaphylaxis, to any component of the vaccine. People experiencing moderate or severe acute illness with or without fever should delay RSV vaccination until they are improved, as a precaution.

Last reviewed: January 22, 2024

RSVPreF3 (Arexvy, GSK) is supplied as a single-dose vial of lyophilized antigen component (powder) and a single-dose vial of adjuvant suspension component (liquid). Both the liquid and the powder should be stored refrigerated between 2°C and 8°C (36°F and 46°F) in the original package in order to protect vials from light. Do not freeze. Discard if either component has been frozen. After reconstitution, administer immediately or store in the refrigerator between 2°C and 8°C (36°F to 46°F) or at room temperature (defined for this vaccine as up to 25°C [77°F]) for up to 4 hours before use. Discard reconstituted vaccine if not used within 4 hours.

RSVpreF (Abrysvo, Pfizer) is supplied in a kit that includes a vial of lyophilized antigen component (a white powder), a prefilled syringe with a sterile water diluent, and a vial adapter. Store at refrigerated temperatures between 2°C and 8°C (36°F and 46°F) in the original carton. Do not freeze. Discard if frozen. Follow reconstitution guidelines at www.fda.gov/media/168889/download. After reconstitution, administer immediately or store at room temperature (defined for this vaccine as 15ºC to 30ºC [59ºF to 86ºF]) for up to 4 hours. Do not store reconstituted Abrysvo vaccine in the refrigerator or freezer. Discard reconstituted vaccine if not used within 4 hours.

Last reviewed: January 22, 2024

Nirsevimab comes in two single-dose manufacturer-filled syringe (MFS) formulations: 50-mg and 100-mg. Nirsevimab should be stored in the refrigerator between 36°F to 46°F (2°C to 8°C). It may be kept at room temperature 68°F to 77°F (20°C to 25°C) for a maximum of 8 hours. After removal from the refrigerator, nirsevimab must be used within 8 hours or discarded. Store nirsevimab in the original carton to protect it from light until time of use. Do not freeze. Do not shake. Do not expose to heat.

Last reviewed: January 22, 2024

No. Seasonal influenza vaccines are reformulated each year; for this reason, all unused seasonal influenza vaccines expire and should be discarded no later than the end of June each season. RSV products (vaccines and preventive antibody) do not change each season and products in your storage unit now may not expire until sometime during or after the next season.

Unless public health authorities advise otherwise, RSV vaccine should not be given during pregnancy after January. Likewise, nirsevimab should not be given to infants after March or before October (unless specifically instructed by public health authorities). Recommendations for timing of RSV vaccination of adults age 60 or older is less precisely defined because vaccination is expected to protect the recipient through two season; however, demand is likely to be lower in spring and summer months. Properly store and clearly label unexpired products remaining in your storage unit during periods when they are not in use and train staff on the timing of these products. Consider storage and labeling that minimizes the risk of mishandling or administration outside the times when the product is recommended to be used.

Last reviewed: January 22, 2024

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