Ask the Experts: All Questions

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Results (1317)

MMR can be given to children as young as 6 months of age who are at high risk of exposure such as during international travel or a community outbreak. However, doses given BEFORE 12 months of age cannot be counted toward the 2-dose series for MMR.

Last reviewed: June 19, 2023

Four egg-based quadrivalent inactivated influenza vaccines (IIV4s) and one cell-based quadrivalent inactivated influenza vaccine (ccIIV4), all given as intramuscular (IM) injections, are available for children age 6 months and older:

  • Afluria Quadrivalent (CSL Seqirus): 0.25 mL/dose for age 6 through 35 months; 0.5 mL/dose for age 3 years and older
  • Fluarix Quadrivalent (GSK): 0.5 mL/dose for age 6 months and older
  • FluLaval Quadrivalent (GSK): 0.5 mL/dose for age 6 months and older
  • Fluzone Quadrivalent (Sanofi): 0.25 mL or 0.5 mL per dose for age 6 through 35 months; 0.5 mL/dose age 3 years and older
  • Flucelvax Quadrivalent (ccIIV4, CSL Seqirus) cell-based (no egg antigen): 0.5 mL/dose (IM) for age 6 months and older

FluMist Quadrivalent (LAIV4, AstraZeneca) egg-based live nasal spray vaccine is 0.2 mL (intranasal, 0.1 mL in each nostril) for healthy, non-pregnant children and teens age 2 years and older.

Last reviewed: September 10, 2023

No. In June 2019, the Advisory Committee on Immunization Practices (ACIP) voted to recommend routine catch-up HPV vaccination of all previously unvaccinated or incompletely vaccinated males age 22 through 26, matching the recommendation for females. HPV vaccination recommendations now differ by age group only, not by biological sex. There is a routine recommendation for vaccination of all people 9 through 26 years of age and a shared clinical decision-making recommendation based on risk and preference for people 27 through 45 years of age.

Current ACIP recommendations for HPV vaccine are listed at www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/hpv.html.

Last reviewed: March 2, 2024

Under section 564 of the Federal Food, Drug, and Cosmetic Act (FD&C Act), the FDA Commissioner may allow unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or prevent serious or life-threatening diseases or conditions caused by chemical, biological, radiological or nuclear threat agents when there are no adequate, approved, and available alternatives. Vaccines that receive an EUA may later be fully licensed by the FDA.

Last reviewed: March 19, 2024

No, it is not. It is only recommended for children and teens ages 9 through 16 who reside in dengue endemic areas.

Last reviewed: February 16, 2022

The Advisory Committee on Immunization Practices (ACIP) does not address this issue. There is no recommended order in which the vaccines should be given. A best practice strategy to decrease injection or procedural pain is to administer the vaccine that causes the most pain (stinging, for example) last. For more information on vaccine administration, please see the “Vaccine Administration” chapter of Epidemiology and Prevention of Vaccine-Preventable Diseases at www.cdc.gov/vaccines/pubs/pinkbook/chapters.html.

Last reviewed: December 28, 2022

Clinicians and patients should make every effort to ensure that two doses of Shingrix are administered within the recommended interval of 2 to 6 months. If more than 6 months have elapsed since the first dose of Shingrix, administer the second dose when possible. Do not restart the vaccine series.

Additional information for clinicians about Shingrix is available on the CDC website at www.cdc.gov/vaccines/vpd/shingles/hcp/index.html.

Last reviewed: March 9, 2022

Vaccine efficacy is 80%–85% following 3 doses of DTaP vaccine. Efficacy data following just 1 or 2 doses are lacking but are likely lower. The most effective way to prevent pertussis in early infancy is to vaccinate the mother between 27 and 36 weeks’ gestation. Antipertussis antibodies generated by the mother’s immune system are passed across the placenta to the fetus. One dose of Tdap should be administered during each pregnancy, preferably between 27 and 36 weeks’ gestation. Available data suggest that vaccinating closer to 27 weeks will maximize passive antibody transfer to the infant. 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 and that maternal vaccination reduces the risk of infant hospitalization for pertussis by 90% (www.cdc.gov/pertussis/pregnant/hcp/vaccine-effectiveness.html).

Last reviewed: March 31, 2022

Yes. Patient-held cards are an extremely important part of a person’s medical history. The person may move to another state or need medical care at a facility within or outside the state without access to the IIS in which their records are documented, and the personal record may be the only vaccination record available.

Last reviewed: June 6, 2023

No. If a healthy child receives a dose of Hib vaccine at 15 months of age or older, he or she does not need any further doses regardless of the number of doses received before 15 months of age.

Last reviewed: July 31, 2022

No. A healthcare provider’s diagnosis or verification of a history of shingles is acceptable evidence of immunity to varicella. According to ACIP, acceptable evidence of varicella immunity in healthcare personnel includes (1) documentation of 2 doses of varicella vaccine given at least 28 days apart, (2) history of varicella or herpes zoster based on clinician diagnosis, (3) laboratory evidence of immunity, or (4) laboratory confirmation of disease.

Last reviewed: May 16, 2023

No. People with chronic liver disease are not at increased risk for acquiring HAV infection. However, they are at an increased risk for life-threatening, fulminant (severe and sudden) hepatitis if they become infected with hepatitis A. People considered to have chronic liver disease include those with hepatitis B or C infection, cirrhosis, fatty liver disease, alcoholic liver disease, and autoimmune hepatitis.

Last reviewed: June 25, 2023

No. Pediarix is intended to be used only for doses 1, 2, or 3 of the DTaP primary series; consequently, using Pediarix for DTaP #4 is off-label and not recommended. You should take measures to prevent this error in the future. The DTaP, IPV, and HepB doses given in this scenario do not need to be repeated as long as you met the recommended minimum intervals for each vaccine component (DTaP, IPV, HepB). If you did meet the minimum intervals, the doses should be counted as valid.

Last reviewed: July 15, 2023

The following vaccines are recommended for new mothers before they leave the hospital: (1) mothers without documentation of previous Tdap vaccination need a dose to protect themselves; (2) mothers who did not receive influenza vaccination during pregnancy need to be vaccinated if it is still influenza vaccination season (October through March); (3) mothers who tested susceptible to rubella on prenatal testing need MMR vaccine even if they have 1 or 2 documented doses of MMR in their medical record; (4) mothers who are not immune to chickenpox need 2 doses of varicella vaccine – the first dose before hospital discharge and the second dose 4 to 8 weeks after the first dose.

Last reviewed: August 29, 2022

For intervals of 3 months or less, you should use 28 days (4 weeks) as a “month.” For intervals of 4 months or longer, you should consider a month a “calendar month”: the interval from one calendar date to the next a month later. This is a convention that was introduced on the childhood schedule in 2002 and discussed in the paper “Evaluation of Invalid Vaccine Doses” (Stokley S, Maurice E, Smith PJ, et al. American Journal of Preventive Medicine, 2004; 26[1]: 34–40).

Last reviewed: June 6, 2023

You can get this information from CDC’s Travel Health website at wwwnc.cdc.gov/travel/. CDC also publishes Health Information for International Travel (a.k.a. the “Yellow Book”) as a reference for those who advise international travelers of health risks. The Yellow Book is written primarily for healthcare providers, although others might find it useful. The contents of the book are available on the CDC Travel Health website. The book can also be ordered in print form. Information on how to order it is on the Yellow Book website at wwwnc.cdc.gov/travel/page/yellowbook-home.

Last reviewed: August 22, 2020

As the name implies, VAERS is a nationwide system for monitoring adverse events following vaccination. VAERS is operated jointly by the FDA and the CDC since 1990.

Last reviewed: August 31, 2022

People who receive a mixed series of OPV and IPV should receive a total of either 3 or 4 doses depending on the age at the time of the last dose. In this case the recent dose of IPV can be counted as the third and final dose in the series. The minimum interval between the next-to-last and last doses in the polio vaccination series is 6 months and the last dose should be at age 4 years or older.

Last reviewed: July 23, 2023

CDC recommends the use of bins, baskets, or some other type of uncovered containers that allow for organization and air circulation for vaccines and diluents within the storage unit. Storage in boxes or bins can help maintain temperature longer, especially if power is lost. Perforated bins may allow for better air circulation around the vaccine, thus helping to maintain correct temperature.

CDC does not have a specific recommendation for brands of containers or bins for storage of vaccine. We recommend that you contact your state immunization program, as they may have suggestions for purchasing this equipment. If you are a Vaccines for Children (VFC) program provider, you should contact your immunization program to ensure that you are in compliance with VFC policy.

Last reviewed: July 26, 2023

The MenB schedule depends upon the product used. Bexsero (MenB-4C, GSK) is a 2-dose series with doses given at least 1 month apart. Trumenba (MenB-Fhbp, Pfizer) is routinely given as a 2-dose series with doses administered at least 6 months apart. A 3-dose Trumenba schedule is recommended for people who need rapid protection against MenB due to an increased risk of MenB disease and for those who are immunocompromised and may not respond optimally to the 2-dose series. For the 3-dose schedule, dose 2 is given 1-2 months after dose 1 and dose 3 at least 6 months after dose 1.

Penbraya (MenABCWY, Pfizer) contains MenB-Fhbp (Trumenba) and is given as two doses, 6 months apart, when vaccination against all 5 serogroups is needed. For adolescents and adults not at increased risk, if Penbraya is used for dose 1 MenB, Trumenba should be administered for dose 2 MenB. For people age 10 years or older at increased risk of meningococcal disease, Penbraya may be used for additional MenACWY and MenB doses (including booster doses) if both vaccines would be given on the same clinic day and at least 6 months have elapsed since most recent Penbraya dose.

Last reviewed: March 24, 2024

Catch-up HPV vaccination is not recommended for adults older than 26 years of age. Instead, shared clinical decision-making regarding HPV vaccination is recommended for some adults aged 27 through 45 years who are not adequately vaccinated and want to be protected from ongoing risk of acquiring new HPV infection.

Ideally, HPV vaccine should be administered before potential exposure to HPV through sexual contact.

Last reviewed: March 2, 2024

ACIP does not identify incarceration as an indication for meningococcal ACWY vaccination. Providers are always free to use their clinical judgment in situations not addressed by ACIP.

Last reviewed: March 24, 2024

People born before 1957 lived through several years of epidemic measles before the first measles vaccine was licensed in 1963. As a result, these people are very likely to have had measles disease. Surveys suggest that 95% to 98% of those born before 1957 are immune to measles. Persons born before 1957 can be presumed to be immune. However, if serologic testing indicates that the person is not immune, at least 1 dose of MMR should be administered.

Last reviewed: June 19, 2023

S. pneumoniae bacteria are serotyped based on the polysaccharides in the outer capsule of the bacteria. Serotypes vary in how common they are and in what percentage of pneumococcal disease they cause.

Among the PCV vaccines, PCV13 includes serotypes: 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F. PCV15 includes all PCV13 serotypes plus 22F and 33F. PCV20 includes all PCV15 serotypes plus 8, 10A, 11A, 12F, and 15B. PPSV23 vaccine does not contain serotype 6A or 19A, but contains 19 other serotypes present in PCV20, plus serotypes 2, 9N, 17F, and 20.

1 2 3 4 5 6A 6B 7F 8 9N 9V 10A 11A 12F 14 15B 17F 18C 19A 19F 20 22F 23F 33F
PCV13 x   x x x x x x     x       x     x x x     x  
PCV15 x   x x x x x x     x       x     x x x   x x x
PCV20 x   x x x x x x x   x x x x x x   x x x   x x x
PPSV23 x x x x x   x x x x x x x x x x x x   x x x x x
Last reviewed: April 5, 2024

Yes. ACIP recommends that people who previously received Zostavax receive 2 doses of Shingrix. The first dose of Shingrix may be given a minimum of 8 weeks after Zostavax.

Last reviewed: March 9, 2022

Four egg-based quadrivalent standard dose IIV vaccines (SD-IIV4s), and one cell-based quadrivalent standard dose inactivated vaccine (ccIIV4), all given as intramuscular (IM) injection may be used in adults age 18 or older:

  • Afluria Quadrivalent (CSL Seqirus): 0.5 mL/dose
  • Fluarix Quadrivalent (GSK): 0.5 mL/dose
  • FluLaval Quadrivalent (GSK): 0.5 mL/dose
  • Fluzone Quadrivalent (Sanofi): 0.5 mL/dose
  • Flucelvax Quadrivalent (ccIIV4, CSL Seqirus) cell-based (no egg antigen): 0.5 mL/dose (IM) for adults age 18 or older

Additional products for adults:

FluMist Quadrivalent (LAIV4, AstraZeneca): egg-based, live nasal spray vaccine: 0.2 mL (given intranasally, 0.1 mL in each nostril) for healthy, non-pregnant adults through age 49 years.

Flublok Quadrivalent (RIV4, Sanofi): recombinant, egg-free vaccine: 0.5 mL/dose (given IM) for adults age 18 or older (one of three preferred product options for adults age 65 and older).

Fluzone High-Dose Quadrivalent (egg-based HD-IIV4, Sanofi): 0.7 mL (given IM), for adults age 65 years and older (one of three preferred product options for adults age 65 and older).

Fluad Quadrivalent (egg-based aIIV4 with MF59 adjuvant, CSL Seqirus): 0.5 mL (given IM), for adults age 65 years and older (one of three preferred product options for adults age 65 and older).

Last reviewed: September 10, 2023

Some isolated positive anti-HBc results are false positives (it is the most common false positive HBV marker). If that can be established, the individual can and likely should be vaccinated, assuming there is an indication or desire to be protected. If the positive anti-HBc is believed to be a true positive, the individual would not require vaccination since they have already (presumably) had HBV infection. Isolated positive anti-HBc could indicate low-level chronic infection. In an infant isolated anti-HBc could indicate passive transfer of antibody from a mother who is HBsAg positive, which is why anti-HBc testing of infants is not recommended.

Additional resources for the evaluation of isolated anti-HBc antibody results are available from the University of Washington: www.hepatitisb.uw.edu/go/screening-diagnosis/diagnosis-hbv/core-concept/all and from CDC: www.cdc.gov/hepatitis-b/hcp/diagnosis-testing/#cdc_hcp_diagnosis_interpreting-how-to-interpret-test-results.

Last reviewed: July 21, 2023

ACIP recommends vaccination of preterm infants according to the same schedule and precautions as full-term infants. In preterm infants (as in full-term infants), the maximum chronological age for the first dose is 14 weeks 6 days. Vaccination should not be initiated for infants aged 15 weeks 0 days or older because of insufficient data on safety of dose 1 of rotavirus vaccine in older infants. For more information, see page 19 of ACIP’s recommendations on rotavirus vaccination, available at www.cdc.gov/mmwr/PDF/rr/rr5802.pdf.

Last reviewed: June 7, 2023

With the exception of two vaccines used to prevent smallpox or mpox (previously known as monkeypox), there is no recommendation to wait until a vaccine reaches room temperature before administration. The vaccine should be administered as soon as it is prepared.

The live smallpox (vaccinia) vaccine, ACAM2000 (Emergent Product Development Gaithersburg, Inc.) and the non-replicating, live smallpox and mpox vaccine, Jynneos (Bavarian Nordic) should be brought to room temperature before use, according to the package inserts for these two products.

Last reviewed: December 28, 2022

Yes. The January 2020 ACIP updated statement on the use of Tdap (available at www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6903a5-H.pdf) states that a child who receives a dose of Tdap from age 7–9 years as part of the catch-up series (as in this case), should receive another dose of Tdap at age 11 or 12 years.

Last reviewed: March 31, 2022

The National Childhood Vaccine Injury Act (NCVIA), enacted in 1986, set forth 3 basic requirements for all vaccination providers, which are:

  • Providers must give the patient (or parent/legal representative of a minor) a copy of the relevant federal “Vaccine Information Statement” (VIS) for the vaccine they are about to receive.
  • Providers must record certain information about the vaccine(s) administered in the patient’s medical record or a permanent office log.
  • Providers must document any adverse event following the vaccination that the patient experiences and that becomes known to the provider, whether or not it is felt to be caused by the vaccine, and submit the report to the Vaccine Adverse Event Reporting System (VAERS) at https://vaers.hhs.gov.
Last reviewed: June 6, 2023

If the child received a primary series (2 or 3 doses) of Hib vaccine in the first year of life, then the final (booster) dose of the series may be given as early as 12 months, provided at least 2 months have passed since the last dose. An unvaccinated 12–14-month-old child should receive one dose as a primary series, and a booster dose 2 months later. Unvaccinated healthy children 15–59 months of age need only a single dose of any licensed conjugate Hib vaccine. Some high-risk children 15–59 months of age are recommended for two doses of Hib vaccine based on previous history of incomplete vaccination.

Last reviewed: July 31, 2022

Recombinant zoster vaccine (RZV, Shingrix, GSK) does not count as the first of two doses of varicella vaccine. Shingrix is not licensed and has not been evaluated for the prevention of primary varicella infection. To meet the immigration requirements, you should give a dose of varicella vaccine now and a second dose at least 4 weeks later. The varicella vaccine doses will not be harmful and will allow your patient to meet the regulatory requirement.

Last reviewed: May 16, 2023

Yes. A pregnant person should receive rabies vaccine if indicated. No fetal abnormalities have been reported with the rabies vaccine. A pregnant person can receive routine pre-exposure vaccination against rabies if the risk of exposure is high.

Last reviewed: August 30, 2020

Hepatitis A cannot be differentiated from other types of viral hepatitis on the basis of clinical or epidemiological features alone. Appropriate blood tests must be used.

  • Anti-HAV: Total antibody to HAV. This diagnostic test detects total antibody of both IgG and IgM subclasses of HAV. If positive, it indicates either acute or resolved infection.
  • IgG anti-HAV: IgG antibody is a subclass of anti-HAV. It appears early in the course of infection, remains detectable for the person’s lifetime and provides lifelong protection against disease. Its presence indicates immunity through either HAV infection or HepA vaccination.
  • IgM anti-HAV: IgM antibody is a subclass of anti-HAV. Its presence indicates a recent infection with HAV (6 months or less). It is used to diagnose acute (recently acquired) hepatitis A. Because of the risk of false positive IgM anti-HAV results, people should only be tested for IgM anti-HAV if they are symptomatic and suspected of having acute hepatitis A illness.
  • HAV RNA tests also may be used to diagnose acute infection through the direct detection of viral RNA in serum or stool.

Total anti-HAV, which appears early in the course of infection, remains detectable for the person’s lifetime and indicates lifelong protection against the infection/disease. To confirm a diagnosis of acute HAV infection, serologic testing for IgM anti-HAV is required. In the majority of persons, serum IgM anti-HAV becomes detectable 5 to 10 days before onset of symptoms and lasts about 6 months. However, there have been reports of persons who test positive for IgM anti-HAV for up to a year or more following infection. An educational program on the interpretation of hepatitis A serology is available on the CDC website at www.cdc.gov/hepatitis/resources/professionals/training/serology/training.htm.

Last reviewed: June 25, 2023

FDA licensed Pentacel in 2008 as a 4-dose series in infants and children at ages 2, 4, 6, and 15–18 months. It should not be used for any dose in the primary series for children age 5 years or older or as the booster dose for children ages 4 through 6 years. The DTaP-IPV component is supplied as a sterile liquid, which is used to reconstitute lyophilized (freeze-dried) ActHIB vaccine. The two components of the vaccine should be stored together in the carton to reduce the chance of giving one component of the vaccine without the other. The DTaP-IPV component should never be administered alone.

Last reviewed: July 15, 2023

Yes. Receipt of RhoGam is not a reason to delay vaccination. See the ACIP “General Best Practices Guidelines for Immunization” at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html.

Last reviewed: August 29, 2022

No. Dengvaxia is FDA-licensed only for children and teens ages 9 through 16 years.

Last reviewed: February 16, 2022

A refrigerator or freezer that is NSF-certified for vaccine storage means the units have been tested and certified to meet the NSF/American National Standards Institute (ANSI) 456 standard. The NSF/ANSI 456 standard (or simply “NSF 456” standard) defines the criteria for construction and performance of vaccine refrigerators and freezers used in healthcare settings where vaccines are given. These criteria were developed through a collaboration with NSF, CDC, healthcare providers, public health agencies, equipment manufacturers, and vaccine manufacturers, including experts from Immunize.org.

The NSF 456 certification is a voluntary standard. CDC does not require NSF-certified units for vaccine storage in the Vaccines for Children program or any other federal program. Not all storage units capable of reliably storing vaccines have this certification; however, all storage unit models with this certification have been designed and proven to properly store vaccines under a range of normal clinic conditions. NSF-certified units would be good options for clinic staff to consider when purchasing vaccine storage units.

Last reviewed: July 26, 2023

Infants who will travel outside the United States should be up to date for all routinely recommended vaccines. One dose of MMR is recommended for infants age 6 through 11 months before international travel. This dose does not count toward the two doses needed to complete the childhood schedule. Infants 6 through 11 months of age traveling to an area at risk for hepatitis A exposure also should receive a dose of hepatitis A vaccine. This dose does not count toward the two doses needed to complete the childhood schedule. Infants younger than age 12 months traveling to a hepatitis A endemic area are not recommended to receive immune globulin for prevention of hepatitis A because immune globulin could interfere with the response to MMR. Varicella vaccine is not recommended before age 12 months, even for travelers. For other vaccine recommendations for travelers, consult the CDC travel website at wwwnc.cdc.gov/travel/.

Last reviewed: August 22, 2020

Reports can be submitted online through the VAERS website or by completing and uploading a writable PDF VAERS report form. Both options can be accessed on the VAERS website at vaers.hhs.gov/reportevent.html. If you need further assistance with reporting to VAERS, please email info@VAERS.org or call 1-800-822-7967.

Last reviewed: August 31, 2022

Most reactions to this vaccine are mild, such as soreness and redness at the injection site. Moderate problems, including hives, pain in the joints, and fever, are possible in a small percentage of patients (6%) given booster doses. Once initiated, rabies prophylaxis should not be interrupted or discontinued because of local or mild systemic adverse reactions to rabies vaccine. Usually, such reactions can be successfully managed with anti-inflammatory and antipyretic agents, such as ibuprofen or acetaminophen.

Last reviewed: May 14, 2023

It is important to know the federal requirements for documenting the vaccines administered to your patients. The requirements are defined in the National Childhood Vaccine Injury Act enacted in 1986. The law applies to all routinely recommended childhood vaccines, regardless of the age of the patient receiving the vaccines. The only vaccines not included in this law are COVID-19, pneumococcal polysaccharide, zoster, and certain infrequently used vaccines, such as rabies and Japanese encephalitis.

The following information must be documented on the patient’s paper or electronic medical record or on a permanent office log:

  1. The vaccine manufacturer.
  2. The lot number of the vaccine.
  3. The date the vaccine is administered.
  4. The name, office address, and title of the healthcare provider administering the vaccine.
  5. The Vaccine Information Statement (VIS) edition date located in the lower right corner on the back of the VIS. When administering combination vaccines, all applicable VISs should be given and the individual VIS edition dates recorded.
  6. The date the VIS is given to the patient, parent, or guardian.

The federally required information should be both permanent and accessible.

Federal law does not require a parent, patient, or guardian to sign a consent form in order to receive a vaccination; providing them with the appropriate VIS(s) and answering their questions is sufficient under federal law.

Last reviewed: June 6, 2023

Yes.

Last reviewed: July 23, 2023

Residence in a homeless shelter or halfway house is considered a high-risk indication only for hepatitis A vaccination because of the increased risk of hepatitis A exposure and serious illness among people experiencing homelessness or living in temporary housing. In all other respects, recommendations for vaccinating adult residents would be the same as those for all adults on the ACIP adult immunization schedule. Residents with medical conditions identified on Table 2 of the schedule should be vaccinated according to that table.

Any residents 18 or younger should be vaccinated according to the catch-up recommendations on the ACIP child/teen immunization schedule. People age 19 through 21 years are not recommended routinely to receive MenACWY. MenACWY may be administered through age 21 years as a catch-up vaccination for those who have not received a dose after their 16th birthday.

Last reviewed: March 24, 2024

Healthy adolescents who are not at increased risk for meningococcal B disease should receive 2 doses of Trumenba (MenB-FHbp) administered at 0 and 6 months. If the second dose is given at an interval of less than 6 months, a third dose should be given at least 4 months after the 2nd dose.

For people age 10 years and older at increased risk for meningococcal B disease, 3 doses of Trumenba should be administered at 0, 1–2, and 6 months. The 3-dose series should be used for all people with functional or anatomic asplenia, people with persistent complement component deficiency (an immune system disorder) or those who take a complement inhibitor (examples include eculizumab [Soliris] and ravulizumab [Ultomiris]), microbiologists who work with meningococcal isolates in a laboratory, and people exposed during serogroup B outbreaks.

Penbraya (MenABCWY, Pfizer) contains MenB-Fhbp (Trumenba) and is given as two doses, 6 months apart, when vaccination against all 5 serogroups is needed. For adolescents or adults not at increased risk, if Penbraya is used for dose 1 MenB, Trumenba should be administered for dose 2 MenB. For people age 10 years or older at increased risk of meningococcal disease, Penbraya may be used for additional MenACWY and MenB doses (including booster doses) if both vaccines would be given on the same clinic day and at least 6 months have elapsed since most recent Penbraya dose.

Last reviewed: March 24, 2024

Every vaccine storage unit must have a temperature monitoring device (TMD). CDC recommends that vaccines be monitored using a “digital data logger” (DDL). A DDL provides the most accurate storage unit temperature information, including a detailed record of how long a unit has been operating outside the recommended temperature range (referred to as a “temperature excursion”). Unlike a simple minimum/maximum thermometer, which only shows the coldest and warmest temperatures reached in a unit, a DDL provides a log of the temperature recorded at preset intervals (at least every 30 minutes is recommended).

Many DDLs use a buffered temperature probe, which is the most accurate way to measure actual vaccine temperatures. Temperatures measured by a buffered probe match vaccine temperatures more closely than those measured by standard thermometers, which tend to reflect only air temperature. Temperature data from a DDL can either be downloaded to a computer using special software or retrieved from a website. The software or website may also allow you to set the frequency of temperature readings. Reviewing DDL data regularly is critical to ensure temperature excursions that could damage vaccines do not go on without being addressed. It is important to decide whether independent software or a website program works best for your facility.

Temperature monitoring devices that are NOT recommended include alcohol or mercury thermometers, even if placed in a fluid-filled, biosafe, liquid vial; bimetal stem devices; devices used for food; chart recorders; infrared devices; and devices that do not have a current and valid Certificate of Calibration Testing. Please note that some devices sold in hardware and appliance stores are designed to monitor temperatures for household food storage. They are not calibrated and not accurate enough to ensure vaccines are stored within the correct temperature range. Using these devices can pose a significant risk of damaging vaccines due to undetected out-of-range temperatures.

More details on temperature monitoring are available on pages 10–11 of CDC Vaccine Storage and Handling Toolkit, available at www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf. Additional details about temperature monitoring for COVID-19 and mpox vaccines are available in the addendum at the end of the toolkit.

Last reviewed: July 26, 2023

PCV vaccines are recommended to be given first because this sequence provides the best immune response to both PCV and PPSV23 vaccines. An evaluation of immune response after a second pneumococcal vaccination administered 1 year after an initial dose showed that subjects who received PPSV23 as the initial dose had lower antibody responses after subsequent administration of PCV13 than those who had received PCV13 as the initial dose followed by a dose of PPSV23. Lower antibody responses were also seen in people 65 years and older who received PCV20 1 to 5 years after a dose of PPSV23 compared to those who received PCV20 at least 6 months after a dose of PCV13 or those who received PCV13 followed by PPSV23.

Last reviewed: April 5, 2024

The recommended interval between Shingrix doses is 2 to 6 months. The minimum interval between doses of Shingrix is 4 weeks. If the second RZV dose is given more than 4 days sooner than 4 weeks after the first dose, a valid second dose should be repeated at least 4 weeks after the dose given too early.

For adults who are or will be immunodeficient or immunosuppressed and who would benefit from a shorter vaccination schedule, the second dose can be administered 1–2 months (a minimum of 4 weeks) after the first dose.

Last reviewed: March 9, 2022

Approximately 7% of people do not develop measles immunity after the first dose of vaccine. This occurs for a variety of reasons. The second dose is to provide another chance to develop measles immunity for people who did not respond to the first dose. About 97% of people develop immunity to measles after two doses of measles-containing vaccine.

Last reviewed: June 19, 2023

For people age 6 months through 64 years, CDC recommends any available age-appropriate vaccine product.

For adults age 65 years and older, three flu vaccines are preferentially recommended: Fluzone High-Dose Quadrivalent, Flublok Quadrivalent recombinant, and Fluad Quadrivalent adjuvanted flu vaccines. In June 2022, ACIP concluded that these three vaccines are potentially more effective than standard dose, unadjuvanted flu vaccines. However, if none of the three vaccines are available, people age 65 years and older should get any other age-appropriate flu vaccine.

Review the full explanation for the ACIP decision in the 2022 published ACIP recommendations for influenza vaccination: www.cdc.gov/mmwr/volumes/71/rr/pdfs/rr7101a1-H.pdf.

Last reviewed: September 10, 2023

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

Although new HPV infections are most commonly acquired in adolescence and young adulthood, having a new sex partner at any age is a risk factor for acquiring a new HPV infection. In addition, some people have specific behavioral or medical risk factors for HPV infection or disease, including men who have sex with men, transgender people, and people with immunocompromising conditions. HPV vaccine works to prevent infection among people who have not been exposed to vaccine-type HPV before vaccination. A discussion with your patient is the best way to decide together how much the patient may benefit from HPV vaccination to prevent new HPV infections.

Last reviewed: March 2, 2024

No. Only the updated (2023–2024 Formula) COVID-19 vaccines are currently authorized or approved for use in the United States.

Last reviewed: March 19, 2024

If the product used for a previous dose is unknown, and the infant is at an age when the vaccine can still be given, give a total of 3 doses of rotavirus vaccine. All doses should be administered by age 8 months and 0 days.

Last reviewed: June 7, 2023

Yes. All children less than 5 years old need at least one dose of Hib vaccine on or after the first birthday. The last dose should be separated from the previous dose by at least 8 weeks.

Last reviewed: July 31, 2022

Here are the suggested volumes:

Deltoid:

  • Average 0.5 mL
  • Range 0.5–2 mL

Vastus Lateralis:

  • Average 1–4 mL
  • Range 1–5 mL

Infants and toddlers would fall at the lower end of the range, whereas adolescents and adults would generally fall on the higher end of the range.

Last reviewed: December 28, 2022

The first two doses of Td are valid because they are separated by at least 4 weeks. However, the minimum interval between the second and third doses of tetanus-containing vaccine is 6 calendar months. So, the Td component of the Tdap dose is not valid because it was given only 4 months after the second dose. The pertussis component can be counted as valid. The patient should receive another dose of Td or Tdap 6 months after the invalid Tdap dose.

Last reviewed: March 31, 2022

Reporting of adequate and inadequate is acceptable only if your lab is using mIUs as the measurement for anti-HBs and the cutoff is below 10 mIU for reporting inadequate anti-HBs and 10 mIU or higher for reporting adequate anti-HBs. You should check with your lab to be certain this is being done.

Last reviewed: July 21, 2023

Yes. For everyone whose varicella immunity is based on vaccination, 2 doses of varicella vaccine are recommended.

Last reviewed: May 16, 2023

Yes. On rare occasions, HAV infection has been transmitted by transfusion of blood or blood products collected from donors during the viremic phase of their infection (i.e., when HAV is in the donor’s blood). Since 2002, tests to detect the presence of hepatitis A virus RNA in donated plasma have drastically reduced the risk of hepatitis A transmission from products derived from blood plasma.

Last reviewed: June 25, 2023

In general, no. According to ACIP’s “General Best Practice Guidelines for Immunization”, concerns about spacing between doses of live vaccines not given at the same visit applies only to live injectable or intranasal vaccines. So, live oral cholera vaccine may be administered simultaneously with another vaccine, or at any interval before or after administration of another vaccine. There is one exception: ACIP recommends (based upon expert opinion) that live oral cholera vaccine should be administered at least 8 hours before the first dose of live oral Ty21a typhoid vaccine in order to minimize the risk that the oral cholera vaccine buffer might interfere with the enteric coating of the oral Ty21a vaccine.

Last reviewed: June 6, 2023

Yes, as long as minimum intervals between doses are maintained.

Last reviewed: July 15, 2023

Due to theoretical risk to the developing fetus, ACIP recommends that pregnancy be avoided for four weeks after receiving a live attenuated vaccine (MMR, varicella, live attenuated influenza, yellow fever). This interval may be shorter than that recommended by the manufacturer.

Last reviewed: August 29, 2022

CDC does not recommend Dengvaxia for non-residents of areas where dengue is endemic. If the child spends regular extended periods in Puerto Rico to point that they are considered a part-time resident, the family should consult with the child’s health care provider in Puerto Rico for assessment.

Last reviewed: February 16, 2022

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