Ask the Experts: All Questions

Ask the Experts is one of our most popular destinations for healthcare professionals. Our experts provide clear, easy-to-understand answers to commonly asked questions about vaccines and their use.

How to Find Your Answer

Note: Selecting a filter subcategory may also return results from the primary category. We are working with our vendor to resolve this error.

  • Some filter options may become disabled as you narrow your selections.
  • Filters are easily added and removed. Click or tap on the X to remove individual filters or choose “Reset All Filters” to remove all filters.
Results (1361)

Yes. Tdap vaccination is routinely recommended to be given at 27 through 36 weeks’ gestation during every pregnancy. This CDC recommendation is endorsed by the American College of Obstetricians and Gynecologists (ACOG), the American College of Nurse-Midwives (ACNM), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP). Tdap given during one pregnancy will not provide sufficient protection for subsequent pregnancies. In June 2011 ACIP first voted to recommend that pregnant people who have never received the Tdap vaccine be vaccinated to optimize the concentration of maternal antibodies transferred to the fetus. ACIP made this recommendation with the goal of protecting newborns with maternal antibodies and decreasing the risk of transmission of pertussis to infants shortly after birth. In October 2016, ACIP voted to recommend administering Tdap vaccination early in the 27- through 36-week “window” to maximize passive antibody transfer to the infant. Mothers who have never received Tdap and who do not receive it during pregnancy should receive it immediately postpartum.

Fewer babies are hospitalized for pertussis when Tdap is given during pregnancy rather than during the postpartum period. A large U.S. study found an 85% reduction in the risk of pertussis in infants under 2 months of age whose mothers were vaccinated with Tdap at 27 through 36 weeks’ gestation, compared to infants whose mothers were vaccinated in the hospital immediately following delivery.

When a mother gets Tdap during pregnancy, maternal pertussis antibodies transfer to the newborn, protecting the baby against pertussis in early life, before the baby is old enough to have received vaccination with DTaP. Tdap also protects the mother, making it less likely that she will get infected with pertussis during or after pregnancy.

Recommendations for the use of Tdap in pregnancy are covered in detail here: www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6702a1-H.pdf, pages 22–23.

Last reviewed: March 31, 2022

Intramuscular IG is available in single-use vials (2 mL and 10 mL). It should be administered intramuscularly, preferably in the anterolateral aspects of the upper thigh and the deltoid muscle of the upper arm. Do not use the gluteal region as an injection site because of the risk of injury to the sciatic nerve.

Last reviewed: June 25, 2023

As with all vaccines, a severe allergic reaction (for example, anaphylaxis) to a vaccine component or to a prior dose is a contraindication to further doses of that vaccine. A moderate or severe acute illness is a precaution; vaccination should be deferred until the person’s condition has improved. Because MenACWY is an inactivated vaccine, it can be administered to people who are immunosuppressed as a result of disease or medications; however, response to the vaccine might be less than optimal.

Last reviewed: November 15, 2024

HPV vaccine should be stored at refrigerator temperature between 2°C and 8°C (36°F and 46°F). The vaccine must not be frozen and must not be used if it has been frozen. Protect the vaccine from light. Administer as soon as possible after being removed from refrigeration. The manufacturer package insert contains additional information and can be found at https://www.immunize.org/official-guidance/fda/pkg-inserts/. For complete information on vaccine storage and handling best practices and recommendations, please refer to CDC’s Vaccine Storage and Handling Toolkit at www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf.

Last reviewed: March 2, 2024

Yes. Aging decreases the body’s ability to develop a good immune response after getting influenza vaccine, which places older people at greater risk of severe illness from influenza.

After years of review and deliberation, ACIP voted in June 2022 to recommend that all adults age 65 and older should preferentially receive one of the three different vaccine products that evidence suggests are likely to perform better than standard dose, unadjuvanted vaccines: Flublok recombinant influenza vaccine (RIV, Sanofi), Fluad adjuvanted vaccine (aIIV, CSL Seqirus), or Fluzone High-Dose vaccine (HD-IIV, Sanofi). However, if none of these three vaccines is available at the time of vaccination, any age-appropriate influenza vaccine may be administered.

For a thorough review of the evidence for this recommendation, see the 2022 ACIP recommendations for influenza vaccination: www.cdc.gov/mmwr/volumes/71/rr/pdfs/rr7101a1-H.pdf.

Last reviewed: August 11, 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 (Beyfortus, Sanofi),  at a retail cost of approximately $450 per dose.

RSV vaccination is recommended only once, so the history of RSV vaccination is also important information for future pregnancies when the mother would need to be counseled that RSV vaccination is not an option and the infant should receive nirsevimab after delivery for RSV prevention.

Last reviewed: August 25, 2024

There is no need to restart the series. Give the second dose of HepB now and be sure there are at least 8 weeks between that dose and the third dose. Increasing the interval between the first two doses has little effect on immunogenicity or final antibody concentration. The third dose confers the maximum level of seroprotection but acts primarily as a booster and appears to provide optimal long-term protection. Longer intervals between the last two doses result in higher final antibody levels but might increase the risk for acquisition of HBV infection among people who have a delayed response to vaccination. No differences in immunogenicity have been observed when one or two doses of hepatitis B vaccine produced by one manufacturer are followed by doses from a different manufacturer.

Last reviewed: July 21, 2023

No. Obstructive sleep apnea alone is not an indication for pneumococcal vaccination. However, people with obstructive sleep apnea may have other pulmonary conditions (such as chronic obstructive pulmonary disease) that would put them at increased risk for invasive pneumococcal disease, for which they should be vaccinated.

Last reviewed: November 13, 2024

No. Simply administer the next dose that is currently recommended, using a vaccine from the same manufacturer, if feasible, even if previous doses in the series were an earlier formulation.

Last reviewed: November 16, 2024

Yes. Although oseltamivir is an antiviral drug, it is only effective against influenza A and B viruses. Shingrix does not contain live virus and will not be affected by oseltamivir.

Last reviewed: March 9, 2022

Breakthrough varicella represents replication of wild varicella virus in a vaccinated person. Although most breakthrough disease is very mild, the child is contagious and activities should be restricted to the same extent as an unvaccinated person with varicella disease.

Last reviewed: May 16, 2023

There is no need to wait a specific interval before giving MMR. An injectable steroid dose is not considered immunosuppressive for the purpose of vaccination decisions, and so there is no concern about safety or efficacy of MMR.

Last reviewed: June 19, 2023

A CDC evaluation found Tdap vaccination during the third trimester of pregnancy prevents 78% of pertussis cases in infants younger than 2 months of age. These findings are similar to other studies from the United Kingdom and the United States that suggest that vaccinating the mother during pregnancy is highly effective at protecting infants against pertussis.

When infants do get pertussis, their infection is less severe if their mother received Tdap during pregnancy. A CDC evaluation found maternal vaccination is 90% effective at preventing infant hospitalization from pertussis. Another U.S. study showed that infants whose mothers got Tdap during pregnancy had a significantly lower risk of hospitalization and shorter hospital stays. That same study showed that no infants born to vaccinated mothers required intubation or died of pertussis.

Links to published research on Tdap vaccination during pregnancy are available here: www.cdc.gov/pertussis/hcp/vaccine-recommendations/pregnancy-research.html.

Last reviewed: March 31, 2022

Serious adverse events from GamaSTAN IG are rare. Anaphylaxis has been reported after repeated administration to people with known immunoglobulin A (IgA) deficiency; thus, IG should not be administered to these people. IG products including GamaSTAN have been associated with the formation of blood clots (thrombosis) after administration, particularly if the patient has other risk factors for thrombosis. Patients should be counseled about this risk.

Last reviewed: June 25, 2023

Your practice should put procedures in place to ensure that you always give vaccines by the recommended route because data regarding safety and efficacy of alternate routes are limited. If this does inadvertently happen, ACIP and/or CDC recommends that if hepatitis B, rabies, HPV and inactivated influenza vaccines are administered subcutaneously the doses should not be counted as valid and should be repeated.

ACIP states that If PCV13, Hib, and/or DTaP are administered by the subcutaneous route, providers have the discretion to repeat the doses. There is no minimum interval between the invalid dose and the repeat dose. ACIP and/or CDC recommends that if HepA, MenACWY, IPV, PPSV23, COVID-19, and RZV vaccines are administered subcutaneously, the doses can count and do not need to be repeated. ACIP/CDC has no recommendation for Tdap, Td, MenB, Typhim VI, or JE-VC.

Last reviewed: December 28, 2022

Yes. No safety concerns associated with vaccination have been identified in people vaccinated during pregnancy or their infants.

Last reviewed: November 15, 2024

Although Fluzone High-Dose (HD-IIV) and Fluad (aIIV) are FDA-licensed for people 65 years and older, in June 2024, ACIP recommended that HD-IIV or aIIV are options for administration to people age 18 through 64 years old who have had a solid organ transplant (SOT) and are on immunosuppressive medication regimens. ACIP expressed no preference for HD-IIV or aIIV over any other age-appropriate IIV or RIV vaccines for SOT recipients.

Last reviewed: August 11, 2024

In clinical trials of the three licensed and recommended RSV vaccines, Arexvy (GSK), Pfizer (Abrysvo), and mResvia (Moderna), mild, local injection site reactions (redness, swelling), fatigue, muscle aches, and headache were common.

Last reviewed: August 25, 2024

No. People should not be routinely scheduled to receive a dose earlier than recommended. Schedulers should offer appointments beginning on the date of the recommended interval or later. CDC guidance allows for doses to be given up to 4 days before the recommended interval in order to avoid missed vaccination opportunities when a recipient unexpectedly arrives early and might not return on schedule.

Last reviewed: November 16, 2024

For the 2-dose adolescent schedule, the adult dose of Recombivax HB (1.0 mL dose) is administered to adolescents age 11 through 15 years, with the second dose given 4 to 6 months after the first dose. In immunogenicity studies, antibody concentrations and end seroprotection rates (at least 10 mIU/mL of anti-HBs) were similar with the 2-dose schedule and the 3-dose schedule (0.5 mL dose). As with other HepB vaccination schedules, if administration of the 2-dose schedule is interrupted, it is not necessary to restart the series. Children and adolescents who have begun vaccination with a pediatric (0.5 mL) dose of Recombivax HB should complete the 3-dose series with this dose. If it is not clear which dose an adolescent was administered at the start of a series, the series should be completed with the 3-dose schedule. Heplisav-B, the 2-dose HepB vaccine given with a 4-week interval between doses, is licensed only for adolescents and adults beginning at age 18 years.

Last reviewed: July 21, 2023

Yes. People with HIV infection are at high risk of pneumococcal disease. The pneumococcal vaccination recommended depends on the patient’s age and prior pneumococcal vaccines received. See CDC’s information about risk-based recommendations for pneumococcal vaccination: www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/risk-indications.html.  

The CDC PneumoRecs VaxAdvisor mobile app can be helpful for evaluating the needs of a specific patient. You can learn more and access the app here: www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/app.html.  

Last reviewed: November 13, 2024

Reconstitute recombinant zoster vaccine (RZV, Shingrix, GSK) using only the adjuvant solution provided with the vaccine antigen. After reconstitution, administer Shingrix immediately by the intramuscular route or store the reconstituted vaccine refrigerated between 2° and 8°C (36° and 46°F) and use within 6 hours. Discard reconstituted vaccine if not used within 6 hours or if frozen. If Shingrix is reconstituted with other than the supplied adjuvant solution, it should be repeated. The dose can be repeated immediately. There is no interval that must be met between these doses.

Last reviewed: March 9, 2022

Yes. MMR and varicella vaccines should be given to the healthy household contacts of immunosuppressed children.

Last reviewed: June 19, 2023

No, and this is not recommended.

Last reviewed: August 11, 2024

Available data suggest that healthy children are unlikely to transmit vaccine virus. Transmission of vaccine virus to a household contact has rarely been documented. It appears that transmission of vaccine virus occurs mostly, or perhaps even exclusively, when the vaccinated person develops a rash following vaccination.

Last reviewed: May 16, 2023

Yes. Pregnancy or lactation is not a contraindication to IG administration if clearly needed.

Last reviewed: June 25, 2023

In general, if the error is discovered on the same clinic day, you can administer the other “half” of the dose on that same day. If the error is discovered later, the dose should not be counted, and then the person should be recalled to the office and given a full age-appropriate repeat dose.

There are, however, two exceptions to the general rule: (1) If a patient sneezes after receiving nasal-spray live attenuated influenza vaccine, count the dose as valid. (2) If an infant regurgitates, spits, or vomits during or after receiving oral rotavirus vaccine, count the dose as valid.

If you give more than an age-appropriate dose, count the dose as valid and notify the patient/parent about the error. Using larger than recommended dosages can be hazardous because of excessive local or systemic concentrations of antigens or other vaccine constituents. Avoid such errors by checking the vaccine vial label 3 times.

Last reviewed: December 28, 2022

Yes. If there is no written documentation that she received a dose of Tdap prior to or during pregnancy, a dose of Tdap should be administered to her immediately postpartum.

Last reviewed: March 31, 2022

No. People with a history of GBS may receive any age-appropriate MenACWY vaccine.

Last reviewed: November 15, 2024

In the clinical trials of both RSVPreF3 (Arexvy, GSK) and RSVpreF (Abrysvo, Pfizer) vaccines, a small number of inflammatory neurologic events, including GBS, were reported after RSV vaccination. The degree to which RSV vaccination might increase the risk for inflammatory neurologic events is not yet fully understood. No cases of GBS or other inflammatory neurologic events were reported after mRNA RSV (mResvia) vaccination during the clinical trials. CDC and FDA are actively monitoring the safety of all of these vaccines through national safety surveillance systems in order to detect and estimate the magnitude of risks that are too small to be measured in clinical trials.

Last reviewed: August 25, 2024

In this specific situation, CDC states that a child age 6 months–4 years who received 1 Moderna and 1 Pfizer-BioNTech COVID-19 vaccine dose for the first 2 doses of COVID-19 vaccine should receive a third dose of the 2024–2025 Formula of either Moderna or Pfizer-BioNTech COVID-19 vaccine at least 8 weeks after the second dose.

For all questions of brand interchangeability, please review CDC’s interim recommendations: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#Interchangeability.

Last reviewed: November 16, 2024

The 2-dose Recombivax HB schedule is only approved for use in children age 11 through 15 years. A 16-year-old child would need two additional doses of pediatric HepB to complete a 3-dose series.

Last reviewed: July 21, 2023

Lupus alone is not an indication for pneumococcal vaccination. However, immunosuppressive medication that may be used to treat lupus could create an indication for administering pneumococcal vaccines. Also, certain complications of lupus (such as nephrotic syndrome) make a person a candidate for pneumococcal vaccination. If pneumococcal vaccination is indicated, administer either PCV20 or PCV21 alone or PCV15 followed by PPSV23 one year later. If the patient is immunosuppressed and is receiving a combination of PCV15 followed by PPSV23, consider using a minimum interval of at least 8 weeks between doses if more rapid protection from serotypes unique to PPSV23 is desired.

Last reviewed: November 13, 2024

Shingrix has been shown to be immunogenic when given by the subcutaneous route. A dose erroneously given by this route does not need to be repeated.

Last reviewed: March 9, 2022

Transmission of varicella vaccine virus is rare. However, if a pregnant or immunosuppressed household contact of a vaccinated person is known to be susceptible to varicella, and if the vaccinee develops a rash 7 to 21 days following vaccination, it is prudent that they avoid prolonged close contact with the susceptible person until the rash resolves.

Last reviewed: May 16, 2023

The recommended schedule for the primary series given to an unvaccinated person is dose 1 now, dose 2 in 4 weeks, and dose 3 in 6 to 12 months. Tdap should replace at least 1 dose of Td, preferably between 27 and 36 weeks’ gestation to maximize the maternal antibody response and passive antibody transfer to the infant.

Last reviewed: March 31, 2022

Yes. The DTaP in the Pentacel can be counted. Although Pentacel is licensed as a 4-dose series and this may represent a fifth dose of Pentacel (in which case it would be off-label use), the dose of DTaP counts as the fifth dose of DTaP.

Last reviewed: December 28, 2022

Based on the weight and dosage provided (40 lbs and 15 mg/week), the child is currently receiving more than 0.4 mg/kg/week of methotrexate. This meets the Infectious Disease Society of America (IDSA) definition of high-level immunosuppression. Administration of both varicella and MMR vaccines are contraindicated until such time as the methotrexate dosage can be reduced. The 2013 IDSA definition of low-level immunosuppression for methotrexate is a dosage of less than 0.4 mg/kg/week. For additional details, see the 2013 IDSA Clinical Practice Guideline for Vaccination of the Immunocompromised Host: cid.oxfordjournals.org/content/early/2013/11/26/cid.cit684.full.pdf.

As a general rule, whenever feasible, it is recommended that non-live and live vaccines be administered 2 or more weeks before initiating immunosuppressive medications include human immune mediators like interleukins and colony-stimulating factors, immune modulators, and medicines like tumor necrosis factor-alpha inhibitors and anti-B cell agents. See CDC General Best Practice Guidelines for Immunization section on altered immunocompetence: www.cdc.gov/vaccines/hcp/imz-best-practices/altered-immunocompetence.html.

Last reviewed: June 19, 2023

Yes. IG may be given any time before or after inactivated vaccines like HepA. However, the antibodies in IG may interfere with the effectiveness of certain live-virus vaccines, such as measles, mumps, and rubella (MMR) and varicella vaccines. CDC recommends waiting at least 6 months from the date of IG administration before administering MMR and varicella vaccines.

Last reviewed: June 25, 2023

Store any brand of MenACWY, MenB, or MenABCWY vaccine at refrigerator temperature, between 2° and 8°C (between 36° and 46°F). These vaccines must not be frozen. Vaccine that has been frozen or exposed to freezing temperature should not be used. Do not use after the expiration date.

Last reviewed: November 15, 2024

People with cancer need to be protected from influenza. All cancer patients should receive an age-appropriate inactivated or recombinant influenza vaccine. They should not be given the live virus vaccine, FluMist (LAIV). Cancer patients and survivors are at higher risk for complications from influenza, including hospitalization and death. Here is a helpful CDC web page on cancer and influenza for patients: www.cdc.gov/cancer/flu.

Last reviewed: August 11, 2024

In clinical trials, the vast majority of infants had no side effects detected after nirsevimab (Beyfortus, Sanofi) 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: August 25, 2024

The dosage depends on the schedule and manufacturer of the vaccine that you are using. For children 11 through 15 years of age, the 2-dose Recombivax HB volume is 1.0 mL. Otherwise, the 3-dose schedule of Recombivax HB or Engerix B is 0.5 mL through age 19 years. Heplisav-B, the 2-dose HepB vaccine given with a 4-week interval between 0.5 mL doses, is licensed for adolescents and adults beginning at age 18 years. Immunize.org offers a handy resource with charts detailing the correct dosages and schedules for monovalent HepB and HepA vaccines and combination products that include HepA and HepB vaccines. Go to www.immunize.org/catg.d/p2081.pdf.

Last reviewed: July 21, 2023

Recommendations vary among adults depending upon age, pneumococcal conjugate (PCV) or polysaccharide (PPSV) vaccination history (including PCV13, PCV15, PCV20, PCV21, and PPSV23), and pneumococcal vaccine products available:

  • Adults age 19 or older with diabetes and no history of receiving any pneumococcal vaccination as an adult should receive either PCV20 or PCV21 alone or a series of PCV15 followed in one year by PPSV23. No further doses are recommended. 
  • People with diabetes who are age 19 through 49 and have already received one dose of PPSV23 may receive one dose of any of the currently recommended PCV options (PCV15, PCV20, or PCV21) one year after the dose of PPSV23; no further doses of PPSV23 are recommended. 
  • People with diabetes and age 50 or older who received PCV13 and PPSV23 before age 50, should receive one dose of PCV20 or PCV21. PCV20 or PCV21 should be given at least 5 years after the last pneumococcal vaccination.  
  • People with diabetes who received PCV13 at any point and have received a PPSV23 vaccination since turning 65 are not routinely recommended to receive any additional doses of pneumococcal vaccine. However, they have the option to receive a dose of PCV20 or PCV21 at least 5 years after their most recent pneumococcal vaccination on the basis of shared clinical decision-making, based upon their risk of pneumococcal disease and desire for additional protection. 
Last reviewed: November 13, 2024

The Shingrix adjuvant solution may contain up to 0.75 mL of liquid. The entire volume of the adjuvant solution should be withdrawn and used to reconstitute the lyophilized vaccine. After mixing, withdraw the recommended dose of 0.5 mL. Discard any reconstituted vaccine left in the vial.

Last reviewed: March 9, 2022

No.

Last reviewed: November 13, 2024

Inactivated influenza vaccine or recombinant influenza vaccine should be administered beginning at least 6 months after bone marrow transplant and annually thereafter for the life of the patient. A dose of vaccine can be given as early as 4 months after transplant, but a second dose should be considered in this situation. A second dose is recommended routinely for all children younger than 9 years receiving influenza vaccine for the first time.

Last reviewed: August 11, 2024

An 8-month-old is likely to have residual passive varicella antibody from his or her mother. The vaccine probably will have no effect, and no action is necessary. The dose should not be counted, and the child should be revaccinated on schedule at 12 through 15 months of age.

Last reviewed: May 16, 2023

Please see details of the recommendations for the use of IG for the prevention of hepatitis A provided in Table 4 (page 19) and Appendices A and B of the 2020 ACIP recommendations for the prevention of hepatitis A infection: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.

Below is a brief summary of the recommendations:

Preexposure prophylaxis with IG for travel to areas of intermediate or high hepatitis A endemicity:

  • Infants younger than age 6 months and other travelers for whom HepA vaccine is declined or contraindicated
  • Previously unvaccinated people with chronic liver disease vaccinated within 2 weeks of departure may consider IG in addition to vaccination, based upon the clinician’s risk assessment
  • Previously unvaccinated people who are immunocompromised may consider IG in addition to vaccination, regardless of the timing of vaccination, based upon the clinician’s risk assessment
  • Previously unvaccinated people who are over age 40 years and vaccinated within 2 weeks of departure may consider IG in addition to vaccination, based upon the clinician’s risk assessment

Postexposure prophylaxis with IG within 2 weeks after exposure to hepatitis A virus (HAV):

  • Infants under age 12 months
  • Previously unvaccinated immunocompromised adults (including HIV+), in addition to vaccination
  • Previously unvaccinated adults with chronic liver disease, in addition to vaccination
  • Previously unvaccinated adults over age 40 years, consider IG in addition to vaccination, based upon clinician risk assessment
  • People with HIV infection, previously vaccinated, consider IG following a high-risk exposure (household or sexual contact), based upon clinician risk assessment
Last reviewed: June 25, 2023

There are no data on the effectiveness of pneumococcal conjugate vaccine given by the intravenous route. The patient has renal disease, so it is important to ensure that the dose they receive is effective. CDC recommends repeating the dose.

Last reviewed: December 28, 2022

Yes. ACIP looked into this issue and included related information in its recommendations published in MMWR on February 22, 2013 (www.cdc.gov/mmwr/preview/mmwrhtml/mm6207a4.htm). ACIP reviewed available data on birth statistics and found that among those in the U.S. who have more than one pregnancy, a very small percentage (2.5%) have an interval of 12 months or less between births. The majority of people who have two pregnancies have an interval of 13 months or more between births. Approximately 5% of mothers have four or more pregnancies. ACIP concluded that (1) the interval between subsequent pregnancies is likely to be longer than is the persistence of maternal anti-pertussis antibodies, (2) most mothers would receive only 2 doses of Tdap, and (3) a small proportion of mothers would receive 4 or more doses.

A theoretical risk exists for severe local reactions (e.g., Arthus reactions, whole limb swelling) for pregnant people who have multiple, closely spaced pregnancies. However, the frequency of side effects depends on the vaccine’s antigen content and product formulation, as well as on preexisting maternal antibody levels related to the interval since the last dose and the number of doses received. The risk for severe adverse events has likely been reduced with current vaccine formulations (including Tdap), which contain lower doses of tetanus toxoid than did older vaccine formulations. ACIP believes the potential benefit of preventing pertussis morbidity and mortality in infants outweighs the theoretical concerns of possible severe adverse events in mothers.

Last reviewed: March 31, 2022

Several studies have documented the safety of measles and mumps vaccine (which are grown in chick embryo tissue culture) in children with severe egg allergy. Neither the American Academy of Pediatrics nor ACIP consider egg allergy as a contraindication to MMR vaccine. ACIP recommends routine vaccination of egg-allergic children without the use of special protocols or desensitization procedures.

Last reviewed: June 19, 2023

Adverse reactions occurring after administration of nirsevimab (Beyfortus, Sanofi) 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: August 25, 2024

All foreign-born people (including immigrants, refugees, asylum seekers, and internationally adopted children) born in Asia, the Pacific Islands, Africa, and other regions with high or intermediate endemicity of HBV infection should be tested for HBsAg, regardless of vaccination status. Initiating HepB vaccination of immigrant children should not be delayed while awaiting HBsAg test results: you may draw blood for testing then administer the first dose of vaccine at the same visit. All people found to be HBsAg-positive should have ongoing medical management by a physician knowledgeable about hepatitis B and its complications.

Last reviewed: July 21, 2023

A person who is not moderately or severely immunocompromised and received a single dose of Novavax COVID-19 vaccine more than 2 months ago may receive a single dose of any licensed or authorized 2024–2025 Formula COVID-19 vaccine, including Novavax.

Last reviewed: November 16, 2024

In April 2022, CDC published updated recommendations from the Advisory Committee on Immunization Practices (ACIP) for the use of hepatitis B vaccine (HepB) in adults. In addition to routine universal childhood HepB vaccination, CDC now recommends catch-up vaccination of all adults younger than age 60 years not previously vaccinated. CDC also recommends that healthcare providers offer HepB vaccination to all adults age 60 or older and routinely given to any adult in this age group known to be at risk. Access the ACIP recommendation: www.cdc.gov/mmwr/volumes/71/wr/pdfs/mm7113a1-H.pdf.

Last reviewed: July 21, 2023


1:17

View All Video Questions

Last reviewed: December 7, 2023

In March 2023, CDC published updated hepatitis B screening and testing guidelines for all adults age 18 years or older. In brief, it is recommended that all adults should be serologically screened for hepatitis B at least one time using a triple panel test, regardless of vaccination history. The triple panel includes antibody
to hepatitis B surface antigen (anti-HBs), total core antibody (anti-HBc), and surface antigen (HBsAg). Pregnant people should be tested for HBsAg during each pregnancy, regardless of testing or vaccination history. After the one-time screening, unvaccinated, susceptible individuals at ongoing risk should be tested periodically for infection. In addition, anyone who requests testing should be tested. Access the CDC recommendations: www.cdc.gov/mmwr/volumes/72/rr/pdfs/rr7201a1-H.pdf.

Last reviewed: July 21, 2023

Anyone can be infected with hepatitis B. Everyone can benefit from knowing their status and being protected. The majority of adults reported to CDC in recent years with acute hepatitis B have no reported risk factor for infection. Risk factors for exposure are so numerous and diverse that most adults, even those who don’t think of themselves as at risk, may find themselves at risk at some point in their lives.

Infants and children have been routinely vaccinated since the 1990s. As a result, we see very little hepatitis B in the routinely vaccinated age groups; however, rates have been steady or rising in unvaccinated older adults. CDC recommends extending this vaccine protection to all adults in a catch-up vaccination program. This is a crucial step toward the goal of eliminating hepatitis B and the liver disease and cancer it causes.

Last reviewed: July 21, 2023


1:47

View All Video Questions

Last reviewed: December 7, 2023

PreHevbrio (VBI, 3-dose series), Heplisav-B (Dynavax, 2-dose series), and Twinrix (GSK, combination HepA-HepB, 3-dose series) are approved for adults age 18 years and older. Engerix-B (GSK) and Recombivax HB (Merck), both administered as a 1.0 mL 3-dose series, are approved for adults age 20 years and older; young adults who are age 19 receive the 0.5 mL pediatric dose of Engerix-B and Recombivax HB.

Last reviewed: July 21, 2023

According to the American Pharmacist Association, all states allow pharmacists to administer zoster vaccine. Not all pharmacists provide vaccination services, and of those who do, not all administer zoster vaccine. It is best to call the pharmacy ahead of time to find out if they have Shingrix to administer to your patients. The vaccine must be administered in the pharmacy. Do NOT instruct the patient to transport the vaccine from the pharmacy back to your office. This could damage the potency of the vaccine.

Last reviewed: March 9, 2022

Varicella zoster immune globulin (VariZIG, Saol Therapeutics) is a human blood product prepared from plasma obtained from healthy, volunteer blood donors identified by routine screening to have high antibody titers to varicella-zoster virus. The first varicella zoster immune globulin, VZIG, became available in 1978. In a study of immunocompromised children who were administered VZIG within 96 hours of exposure, approximately one in five exposed children developed clinical varicella, and one in 20 developed subclinical disease compared with 65%—85% attack rates among historical controls. In 2006, VZIG was discontinued and a new product, VariZIG, became available.

Last reviewed: May 16, 2023

No, it is not recommended to give another dose of Tdap in such cases. Optimal timing for Tdap administration is between 27 and 36 weeks’ gestation because that stage of pregnancy is best for transplacental antibody movement to the fetus.

More information is available at www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6702a1-H.pdf, pages 22–23.

Last reviewed: March 31, 2022

Hepatitis A vaccination is recommended for people age 6 months or older who are traveling to or working in an area of the world at intermediate or high risk of hepatitis A transmission. Areas of low risk include the United States, Canada, Japan, New Zealand, Australia and Western Europe. Visit the CDC’s Traveler Health website for more information about specific destinations and current outbreaks or travel notices (https://wwwnc.cdc.gov/travel/). When in doubt, vaccinate.

Last reviewed: June 25, 2023

This page was updated on .

Our Affiliated Sites

For the Public: VaccineInformation.org
For Coalitions: ImmunizationCoalitions.org
65+ Flu Defense
Protect vulnerable, older adult patients from influenza.
Give2MenACWY.org
Improve protection from meningococcal serogroups ACWY.
Mass Vaccination Resources
Access guidance documents, toolkits, and helpful resources.
NAIIS
Home of the National Adult and Influenza Immunization Summit.