Ask the Experts: All Questions

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Results (1355)

Yes, VFC-supported HepA vaccine is available for children 12 months through 18 years who are VFC-eligible. In addition, combination HepA and HepB vaccine (Twinrix; GSK) is also available for people who are age 18 years who are VFC-eligible.

Last reviewed: June 25, 2023

In the case of an expired live vaccine, the issue is not necessarily the routine minimum interval (three months in the case of varicella and ProQuad vaccines), but the interval that would prevent viral interference if the expired vaccine happened to be still viable. This interval is considered to be four weeks (28 days). The repeat dose should be administered four weeks after the expired dose.

Last reviewed: July 15, 2023

All providers who administer vaccinations should be aware of the potential for syncope (fainting) after vaccination and take appropriate measures to prevent it. Thus, clinicians should (1) make sure that people who are being vaccinated are always seated; (2) be aware of symptoms that precede fainting (weakness, dizziness, pallor, etc.); and (3) take appropriate measures to prevent injuries if such symptoms occur.

Immunize.org has two pertinent educational pieces for healthcare professionals: “Medical Management of Vaccine Reactions in Children and Teens” at www.immunize.org/catg.d/p3082a.pdf and “Medical Management of Vaccine Reactions in Adult Patients” at www.immunize.org/catg.d/p3082.pdf.

CDC studies have shown that about 80% of fainting episodes occur within 15 minutes of receiving the vaccine. Vaccine providers should strongly consider observing vaccinated people for 15 minutes after vaccination in accordance with ACIP’s General Best Practices Guidance for Immunization (see www.cdc.gov/vaccines/hcp/acip-recs/general-recs/administration.html). This is particularly important when vaccinating adolescents and young adults. CDC has posted additional information on this topic at www.cdc.gov/vaccinesafety/concerns/fainting.html.

Last reviewed: December 28, 2022

ACIP has recommended vaccinating during pregnancy with inactivated influenza vaccine since 1997. Studies have shown that pregnant people are at increased risk for complications, hospitalization, and even death from influenza because of the increased physiologic strain of pregnancy on their heart, lungs, and immune system. Vaccination can occur in any trimester, including the first.

Infants younger than 6 months old are at high risk of influenza-related complications, but influenza vaccine is not recommended for them because the immune response to influenza vaccination is limited before 6 months of age. Vaccinating during pregnancy provides maternal antibodies to the fetus which helps protect infants against influenza during the first 6 months of life until they can get vaccinated at age 6 months. Vaccinating pregnant people protects them, their unborn babies, and their babies after birth.

Last reviewed: August 11, 2024

The supply of 50-mg manufacturer-filled syringes (MFS) of nirsevimab (Beyfortus) 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: August 25, 2024

Immunocompromised people who require an initial series of 3 doses of mRNA COVID-19 vaccine or two doses of Novavax COVID-19 vaccine should receive the initial series using the same brand, unless it is not feasible. If the same brand (referred to as a homologous dose) cannot be used for all primary series doses (e.g., the brand is unavailable at the time of the vaccination visit, the previous brand is unknown, or the patient would not be vaccinated with the previous brand due to a contraindication or other reason), then administer another appropriate brand. CDC recommends homologous doses for all doses administered to children younger than age 5 years. If the immunocompromised recipient is age 5 years or older, once the initial series is complete, any appropriate brand may be used for subsequent doses. CDC provides additional information at: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#Interchangeability.

Last reviewed: August 31, 2024

Multiple sclerosis is not a contraindication to any vaccine, including pneumococcal vaccines.

People with multiple sclerosis may be on immunosuppressive medication. If so, immunosuppressed people should receive PCV20 or PCV21 alone or PCV15 followed by PPSV23 a minimum of 8 weeks later.

For additional details, see  www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/risk-indications.html.  

Last reviewed: November 13, 2024

Yes. Doses of MenACWY given before 10 years of age should not be counted as part of the series. If a child received a dose of MenACWY before age 10 years, they should receive a dose of MenACWY at 11 or 12 years and a booster dose at age 16 years. A dose of MenACWY administered at age 10 may count as the first adolescent dose normally given at 11 or 12.

Last reviewed: November 15, 2024


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Last reviewed: May 23, 2023

Yes. An HBsAg-positive mother who wishes to breastfeed should be encouraged to do so, including immediately following delivery. However, the infant should receive HBIG and HepB vaccine within 12 hours of birth. Although HBsAg can be detected in breast milk, studies done before HepB was available showed that breastfed infants born to HBsAg-positive mothers did not demonstrate an increased rate of perinatal or early childhood HBV infection. More recent studies have shown that, among infants receiving post-exposure prophylaxis to prevent perinatal HBV infection, there is no increased risk of infection among breastfed infants.

Last reviewed: July 21, 2023

Yes, administration of a different inactivated or live vaccine, either at the same visit or at any time before or after HPV vaccine, is acceptable because HPV is not a live vaccine.

Last reviewed: March 2, 2024

In pre-licensure clinical trials of Shingrix in immunocompetent adults age 50 years or older, the most common adverse reactions were pain at the injection site (78%), myalgia (45%), and fatigue (45%). Any grade 3 adverse event (reactions related to vaccination which were severe enough to prevent normal activities) was reported in 17% of vaccine recipients compared with 3% of placebo recipients. Grade 3 injection-site reactions (pain, redness, and swelling) were reported by 9% of vaccine recipients, compared with 0.3% of placebo recipients. Grade 3 solicited systemic events (myalgia, fatigue, headache, shivering, fever, and gastrointestinal symptoms) were reported by 11% of vaccine recipients and 2.4% of placebo recipients. The occurrence of local grade 3 reactions did not differ by vaccine dose. However systemic grade 3 reactions were reported more frequently after dose 2.

Rates of serious adverse events (an undesirable experience associated with the vaccine that results in death, hospitalization, disability or requires medical or surgical intervention to prevent a serious outcome) were similar in vaccine and placebo groups.

Among immunocompromised recipients of RZV, local grade 3 reactions occurred in 10.7% to 14.2% of RZV recipients, and systemic grade 3 reactions occurred in 9.9% to 22.3% of RZV recipients, compared with 0% to 0.3% and 6.0% to 15.5%, respectively, among placebo recipients. Limited studies have found no evidence of an increased risk of immune-mediated diseases, graft-versus-host-disease, or transplant rejection among certain categories of immunocompromised RZV recipients.

Last reviewed: March 9, 2022

Yes. A TST can be applied before or on the same day that MMR vaccine is given. However, if MMR vaccine is given on the previous day or earlier, the TST should be delayed for at least 28 days. Live measles vaccine given prior to the application of a TST can reduce the reactivity of the skin test because of mild suppression of the immune system.

Last reviewed: June 19, 2023

This is not necessary unless the person who was vaccinated develops a rash.

Last reviewed: May 16, 2023

ACIP recommends the following:

  • All adults age 19 years and older who have not yet received a dose of Tdap should receive a dose.
  • All pregnant people should receive a dose of Tdap during each pregnancy, preferably between 27 and 36 weeks’ gestation. Mothers who have never received Tdap and who do not receive it during pregnancy should receive it immediately postpartum.
  • A person who has not yet received a dose of Tdap can be given a dose of Tdap regardless of the interval since the person last received a tetanus or diphtheria toxoid-containing vaccine.
  • Providers should not miss an opportunity to vaccinate adults age 65 years and older with Tdap. When feasible, give Boostrix to adults age 65 and older. However, either vaccine product (Adacel or Boostrix) provides protection and is considered valid for use in people in this age group.
  • For adults not previously vaccinated with Tdap who need wound management care to prevent tetanus, Tdap is preferred over Td.
  • For adults who have received an initial dose of Tdap, Tdap may be administered in any situations where Td only was previously recommended, including as the decennial (every 10-years) booster dose.
Last reviewed: March 31, 2022

You do not need to start the series over again. The immunogenicity of 1 dose of HepA vaccine is 94% to 100%; studies have shown persistent protection from a single dose lasting more than 10 years. To ensure optimal long-term protection it is important to administer the second dose.

Last reviewed: June 25, 2023

Diluents are not interchangeable, except for the sterile water used in Merck’s measles-mumps-rubella (MMR), measles-mumps-rubella-varicella (MMRV), and varicella vaccines. No other diluent can be used for these vaccines, and these diluents must not be used to reconstitute any other lyophilized vaccine.

If the wrong diluent is used, the vaccination should always be repeated. If an inactivated vaccine is reconstituted with the wrong diluent and is administered, the dose is invalid and should be repeated as soon as possible. If a live vaccine is reconstituted with the wrong diluent and is administered, the dose is invalid. If the dose can’t be repeated on the same clinic day, it needs to be repeated no earlier than four weeks after the invalid dose. This spacing is due to the effects of generating a partial immune response that could suppress the live replication of subsequent doses, even of the same live vaccine.

Immunize.org has produced a printable document with details about vaccines that require diluents and how to use them: www.immunize.org/catg.d/p3040.pdf.

Last reviewed: December 28, 2022

Yes, however, this issue is not addressed in the 2010 MMRV ACIP recommendations. Although this is off-label use, CDC recommends that when a dose of MMRV is inadvertently given to a patient age 13 years and older, it may be counted towards completion of the MMR and varicella vaccine series and does not need to be repeated.

Last reviewed: July 15, 2023

Studies done in children showed possible interference with the response to PCV7 when PCV7 and the Menactra brand of MenACWY-D (by Sanofi) were given simultaneously. For this reason, Menactra was recommended not to be given at the same time as PCV. However, Menactra is no longer available, so this is no longer a consideration.

Available brands of MenACWY, including MenACWY-CRM (Menveo, GSK), MenACWY-TT (MenQuadfi, Sanofi), as well as the pentavalent MenABCWY (Penbraya, Pfizer), may be administered at the same time or any time before or after any pneumococcal vaccine.

Last reviewed: November 13, 2024

Pregnant people may receive any age-appropriate inactivated or recombinant influenza vaccine. They should not be given FluMist (LAIV) because it is a live virus vaccine.

Last reviewed: August 11, 2024

Yes, nirsevimab (Beyfortus, Sanofi) 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: August 25, 2024

Primary vaccination with the Janssen COVID-19 Vaccine required only a single dose. People who received the Janssen COVID-19 Vaccine primary dose require only one 2024–2025 Formula dose by Moderna, Pfizer-BioNTech, or Novavax to be up to date. People who are moderately or severely immunocompromised have the option to receive 1 additional 2024–2025 Formula COVID-19 vaccine dose at least 2 months later. Further additional dose(s) may be administered, informed by the clinical judgment of a healthcare provider and the recipient’s personal preference and circumstances. Any further additional doses should be administered at least 2 months after the last 2024–2025 Formula COVID-19 vaccine dose.

Last reviewed: August 31, 2024

ACIP recommends routine booster doses of MenACWY for people two months old or older at ongoing high risk for meningococcal infection (see www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6909a1-H.pdf, Table 3). This group includes people (1) with persistent complement component deficiency (an immune system disorder) or who take a complement inhibitor (examples include eculizumab [Soliris], ravulizumab [Ultomiris], and sutimlimab [Enjaymo]), (2) with anatomic or functional asplenia, (3) with HIV infection, (4) who have higher risk of exposure (including microbiologists who handle Neisseria meningitidis isolates and travelers to or residents of areas with epidemic or hyperendemic meningococcal disease [such as the meningitis belt of sub-Saharan Africa]).

Children at continued high risk who received the last dose of the primary series of MenACWY before age 7 years should receive the next dose 3 years after the most recent dose, then every 5 years as long as risk remains. People at continued high risk who received the last dose of the primary series at age 7 years or older should receive the next dose 5 years after the most recent dose then every 5 years as long as risk remains. Menveo (MenACWY-CRM) is licensed through age 55 years; however, if MenQuadfi (MenACWY-TT, licensed for use at age 2 years and older) is unavailable for an adult age 56 years or older, you may use Menveo.

Last reviewed: November 15, 2024

Yes, unless you live in a state that has enacted legislation restricting use in pregnancy. There is no scientific evidence that thimerosal in vaccines is a cause of adverse events unless the patient has a systemic allergy to thimerosal.

Last reviewed: August 11, 2024

ACIP recommends varicella vaccine for healthy household contacts of pregnant people and immunosuppressed people. Although there may be a small risk of transmission of varicella vaccine virus to household contacts, the risk is much greater that the susceptible child will be infected with wild-type varicella, which could present a more serious threat to household contacts.

Last reviewed: September 5, 2020

There is no upper age limit for Tdap vaccination. A dose of Tdap is recommended for all adults. In addition, Tdap may be administered in any situations where Td only was previously recommended.

Last reviewed: March 31, 2022

No. It is also unnecessary to change the needle if it has passed through two stoppers, which is done when a lyophilized vaccine is reconstituted. Changing needles is a waste of resources and increases the risk of needle stick injury.

Last reviewed: December 28, 2022

A person should receive the dosage of HepA vaccine appropriate for their age at the time of administration. You should give the patient one adult dose of HepA to complete the 2-dose series. It is not necessary to restart the vaccine series.

Last reviewed: June 25, 2023

Before vaccination, providers should counsel Shingrix recipients about common expected systemic and local adverse reactions (see related question). Reactions to the first dose do not strongly predict reactions to the second dose.

If a patient experiences side effects, any local (e.g., redness, pain, swelling at the injection site) or systemic (e.g., fever, chills, headache, body aches) reactions typically go away within 72 hours after vaccination. It is generally not recommended to take medication for pain or fever (e.g., acetaminophen or ibuprofen) before vaccination; however, such medications may be taken to alleviate local or systemic symptoms after vaccination, if needed. Shingrix recipients should be encouraged to complete the series even if they experienced a grade 3 reaction to the first dose.

Last reviewed: March 9, 2022

Yes. No data exist on the efficacy or safety of HPV vaccine given by the Subcut route. All data on efficacy and duration of protection are based on a vaccine series administered by the IM route. In the absence of data on Subcut administration, CDC and the manufacturer recommend that a dose of HPV vaccine given by any route other than IM should be repeated. There is no minimum interval between the invalid (Subcut) dose and the repeat IM dose.

Last reviewed: March 2, 2024

Yes, people should receive additional booster doses (every 5 years) if they continue to be at increased risk for meningococcal ACWY infection.

Last reviewed: November 15, 2024

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

Last reviewed: August 25, 2024

The patient should receive a 2024–2025 COVID-19 mRNA dose now, if feasible, of the same brand as the initial two doses, in order to complete the 3-dose primary mRNA vaccine series recommended for people with moderate or severe immunocompromise. Advise the patient that he has the option to receive additional 2024–2025 Formula COVID-19 doses of any brand (at least 2 months apart) as needed, based on his clinical circumstances.

Last reviewed: August 31, 2024

This student should receive two doses of MMR, separated by at least 28 days. A personal history of measles and mumps is not acceptable as proof of immunity. Acceptable evidence of measles and mumps immunity includes a positive serologic test for antibody, birth before 1957, or written documentation of vaccination. For rubella, only serologic evidence or documented vaccination should be accepted as proof of immunity. Additionally, people born prior to 1957 may be considered immune to rubella unless they are women who have the potential to become pregnant.

Last reviewed: June 19, 2023

In the absence of immunosuppressive treatment, a recent history of prostate cancer surgery alone is not an indication for pneumococcal vaccination among people younger than 50 years. 

Last reviewed: November 13, 2024

No. Shingrix contains only a small part of the varicella zoster virus that causes shingles. Shingrix does not contain any live varicella zoster virus.

Last reviewed: March 9, 2022

Because the surgeon is immune, the child’s rash is not a problem and there is no need for the surgeon to restrict activity. In comparing a vaccine rash to wild-type chickenpox infection, transmission is less likely with a vaccine rash and, in general, there are fewer skin lesions.

Last reviewed: May 16, 2023

The “General Best Practice Guidelines for Immunization” (see www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html) makes the generic recommendation that live parenterally or nasally administered vaccines not given on the same day should be separated by at least 28 days. The CDC travel health website recommends that yellow fever vaccine and other parenteral or nasal live vaccines should be separated by at least 30 days if possible. Either interval is acceptable.

Last reviewed: June 19, 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.

If you give more than an age-appropriate dose (for example, an adult dose of HepA vaccine given to a child), count the dose as valid and notify the patient/parent about the error. There may be an increased risk of a local adverse reaction when more than the recommended dose is given. If the error occurred with the first dose of the series the child should still receive the second dose on schedule. Giving a “double” dose for the first dose does not negate the need for a second dose.

Avoid such errors by checking the vaccine vial label 3 times.

Last reviewed: June 25, 2023

Absolutely not. No vaccines should ever be mixed in the same syringe unless the combination has been specifically approved by the FDA.

Last reviewed: December 28, 2022

Your understanding of the general Td/Tdap recommendation is correct, and this is the schedule that should be followed for persons 7 years old and older who have never received tetanus-containing vaccine or who cannot provide documentation of prior vaccination. ACIP recommends that Tdap or Td may be used in situations when only Td was previously recommended. Be sure to document doses administered in your state’s immunization information system so other healthcare providers will have access to the record of immunization and a primary series will not need to be repeated in the future.

Last reviewed: March 31, 2022

Yes. The use of a 4-dose HepB schedule is acceptable when giving the monovalent HepB vaccine birth dose followed by the use of Pediarix (DTaP-HepB-IPV) or Vaxelis (DTaP-IPV-Hib-HepB). The use of a 4-dose HepB schedule, including schedules with a birth dose, has not increased vaccine reactogenicity and results in higher final antibody titers that should correlate with longer duration of detectable antibody. The federal Vaccines for Children (VFC) program provides up to four doses of HepB for VFC-eligible children. You may still use monovalent HepB in a 3-dose series.

Last reviewed: July 21, 2023

Contraindications are the following:

  • HPV vaccine is contraindicated for people with a history of immediate hypersensitivity to any vaccine component, including yeast.
  • The precaution to HPV vaccine is a moderate or severe acute illness with or without fever. Vaccination should be deferred until the condition improves.

HPV vaccines are not recommended for use during pregnancy. If a person is found to be pregnant after starting the vaccination series, the remainder of the 2- or 3-dose series (depending on the age of first HPV vaccination) should be delayed until completion of pregnancy. Pregnancy testing is not needed before vaccination. If a vaccine dose has been administered during pregnancy, no intervention is needed. You can find more information about HPV vaccine and pregnancy in the ACIP recommendations at: www.cdc.gov/mmwr/preview/mmwrhtml/rr6305a1.htm.

Last reviewed: March 2, 2024

The MenACWY booster dose should be given at 14 years (5 years after the primary series) and every 5 years thereafter. The every-5-year booster dose schedule for people with high-risk conditions takes precedence over the routine adolescent schedule.

Last reviewed: November 15, 2024

No. CDC’s Advisory Committee on Immunization Practices (ACIP) does not recommend more than one dose of influenza vaccine per season, except for certain children being vaccinated for the first time.

Last reviewed: August 11, 2024

Nirsevimab (Beyfortus, Sanofi) 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: August 25, 2024

Yes. CDC states that people ages 6 months and older who are moderately or severely immunocompromised have the option to receive 1 additional dose of COVID-19 vaccine at least 2 months following the last recommended 2024–2025 Formula COVID-19 vaccine dose. Further additional dose(s) may be administered, informed by the clinical judgement of the healthcare provider and personal preference and circumstances. Any further additional doses should be administered at least 2 months after the last COVID-19 vaccine dose.

Last reviewed: August 31, 2024

Because pneumococcal recommendations have changed over the years, providers should generally avoid assuming which pneumococcal vaccines a patient has received. Ideally, providers and patients should try to verify which vaccines were received, including by checking medical records and the jurisdiction’s immunization information system (immunization registry) where the patient was likely vaccinated.

Per the CDC “General Best Practices Guidelines for Immunization”, self-reported doses of influenza and PPSV23 are acceptable. All other vaccines must be documented with a written, dated record. This means that if a patient reasonably recalls receiving a PPSV23 after turning 65, you may accept that as a history of PPSV23 and administer a recommended pneumococcal conjugate vaccine option (PCV20, or PCV21).

Alternatively, if vaccination records cannot be obtained, and the patient is uncertain whether they received PCV13 or PPSV23, you may choose to classify the patient as having an unknown vaccination history and administer either PCV20 or PCV21 alone or PCV15 followed by PPSV23 one year later. When giving the PCV15 and PPSV23 series to a patient with an immunocompromising condition, cochlear implant, or cerebrospinal fluid leak, an 8-week minimum interval between PCV15 and PPSV23 may be considered.

Last reviewed: November 13, 2024

The only contraindication is a severe allergic reaction to a vaccine component or following a prior dose.

Last reviewed: March 9, 2022

ACIP recommends that all HCP born during or after 1957 have adequate presumptive evidence of immunity to measles, mumps, and rubella, defined as documentation of two doses of measles and mumps vaccine and at least one dose of rubella vaccine, laboratory evidence of immunity, or laboratory confirmation of disease. Further, ACIP recommends that healthcare facilities should consider vaccination of all unvaccinated healthcare personnel who were born before 1957 and who lack laboratory evidence of measles, mumps, and/or rubella immunity or laboratory confirmation of disease. During an outbreak of measles or mumps, healthcare facilities should recommend 2 doses of MMR separated by at least 4 weeks for unvaccinated healthcare personnel regardless of birth year who lack laboratory evidence of measles or mumps immunity or laboratory confirmation of disease. During outbreaks of rubella, healthcare facilities should recommend 1 dose of MMR for unvaccinated personnel regardless of birth year who lack laboratory evidence of rubella immunity or laboratory confirmation of infection or disease.

Last reviewed: June 19, 2023

A CDC-funded study found that people who had been vaccinated early in pregnancy with an influenza vaccine containing the pandemic H1N1 (H1N1pdm09) component and who also had been vaccinated the prior season with an H1N1pdm09-containing influenza vaccine had an increased risk of spontaneous abortion (miscarriage) in the 28 days after vaccination. This study did not quantify the risk of miscarriage and did not prove that influenza vaccine was the cause of the miscarriage. Earlier studies have not found a link between influenza vaccination and miscarriage. A larger follow-up study also funded by CDC which included 3 more years of data found no association between early miscarriage and influenza vaccination regardless of previous influenza season vaccination. These results are reassuring regarding the safety of influenza vaccination during pregnancy.

CDC, ACIP, and the American College of Obstetricians and Gynecologists (ACOG) all recommend influenza vaccination during any trimester of pregnancy. Influenza poses a danger to pregnant people and the vaccine can prevent influenza in pregnant people and their infants.

Last reviewed: August 11, 2024

There has been only one published report of mother to child transmission of varicella vaccine virus. If the susceptible woman were to be infected with wild varicella virus, the risk of transmission to the infant would be much higher. Breastfeeding is not a contraindication or a precaution to varicella vaccination of the mother when vaccination is indicated.

Last reviewed: May 16, 2023

When injectable vaccine volume is lost (patient moves, syringe leaks), it may be difficult to judge how much vaccine the patient actually received. Use your discretion to determine whether an adequate dose was given. In general, you should treat this as a nonstandard injectable dose and should not count it. If it was an inactivated vaccine, you should re-immunize the person as soon as possible. In the case of Shingrix (RZV; GSK) if the person is still in the office the dose can be repeated immediately; however, if the repeat Shingrix dose cannot be given on the same day CDC recommends that it should be given 4 weeks after the invalid dose.

If it was a live vaccine, you can give another dose if you detect the error on the same clinic day; otherwise, you should wait 28 days to give the next dose. However, if part of a dose of an oral vaccine (rotavirus) was spit out by an infant, count the dose and do not administer a second dose. If a person sneezes after live attenuated influenza vaccine (Flumist; AstraZeneca) the dose can be counted as valid.

Last reviewed: December 28, 2022

No. ACIP recommends that people age 11 years and older who have not yet received Tdap receive a dose of Tdap now. ACIP specifies no waiting interval between administering Td and Tdap.

Last reviewed: March 31, 2022

The efficacy data from the clinical trials were based on age at time of vaccination, and not on the weight of the individual. Hence, the dosage recommendations reflect this age-based efficacy data. The same holds true for HepB vaccine. In addition, higher response rates are expected in younger people, even if their weights are above the norm.

Last reviewed: June 25, 2023

All COVID-19 vaccines are administered intramuscularly. Preparation details and dose volume vary by product.

Last reviewed: August 31, 2024

Yes. A woman with evidence of present or past HPV infection identified through cervical screening may be vaccinated, and should be vaccinated if age 26 or younger. Infection with one type of HPV does not prevent infection with additional types. Vaccination can prevent infections with additional HPV types included in the vaccine. Recipients of HPV vaccinations should be counseled that the vaccine will not have a therapeutic effect on any existing HPV infections or cervical lesions. In other words, vaccination does not treat existing HPV infections or the lesions (warts, cancer, or pre-cancerous changes) caused by them.

Last reviewed: March 2, 2024

If the person cannot provide written documentation of the previous vaccination, you should assume they are unvaccinated and vaccinate accordingly.

Last reviewed: November 15, 2024

According to subject matter experts at CDC, your electronic health record is correct. The CDC website states that HepB dose #4, if given, must be at 24 weeks of age or later, at least 16 weeks from dose #1, and at least 8 weeks from dose #2. There is no minimum interval requirement between dose #4 and the previous dose. This information is not published in any current ACIP statement but it can be found under “Hepatitis B” at www.cdc.gov/cocasa/hcp/reports/algorithm-reference.html.

Last reviewed: July 26, 2024

Only infants younger than age 8 months 0 days are routinely recommended to receive nirsevimab (Beyfortus, Sanofi) 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/Alaska Native children and children with specific conditions that put them at high risk of severe lower respiratory tract disease due to RSV.

Last reviewed: August 25, 2024

In 2008, ACIP reviewed evidence indicating that asthma is an independent risk factor for pneumococcal disease among adults. ACIP also reviewed evidence demonstrating an increased risk of invasive pneumococcal disease among smokers. Consequently, ACIP includes both asthma and cigarette smoking as indications for pneumococcal vaccination among adults age 19 through 49 years. People with these conditions should receive either a single dose of PCV20 or PCV21 alone, or a dose of PCV15 followed one year later by PPSV23. If they have already received PPSV23, but have not had a conjugate vaccine, they should receive a single dose of a recommended pneumococcal conjugate vaccine (PCV15, PCV20, or PCV21) at least one year following their dose of PPSV23.

Last reviewed: November 13, 2024

Yes.

Last reviewed: March 2, 2024

The only precaution is the presence of a moderate or severe acute illness, including having an active case of herpes zoster. If the patient has zoster, vaccination should be deferred until lesions have crusted and symptoms have abated.

There is currently no ACIP recommendation for RZV use in pregnancy; therefore, providers should consider delaying RZV until after pregnancy. There is no recommendation for pregnancy testing before vaccination.

Last reviewed: March 9, 2022

Yes. Healthcare personnel (HCP) with 2 documented doses of MMR vaccine are considered to be immune regardless of the results of a subsequent serologic test for measles, mumps, or rubella. Documented age-appropriate vaccination supersedes the results of subsequent serologic testing. In contrast, HCP who do not have documentation of MMR vaccination and whose serologic test is interpreted as “indeterminate” or “equivocal” should be considered not immune and should receive 2 doses of MMR vaccine (minimum interval 28 days). ACIP does not recommend serologic testing after vaccination. For more information, see ACIP’s recommendations on the use of MMR vaccine at www.cdc.gov/mmwr/pdf/rr/rr6204.pdf, page 22.

Last reviewed: June 19, 2023

No. The needle should be considered to be contaminated. The needle and syringe should be discarded. A new syringe, needle, and dose of vaccine should be used. Generally, a full repeat dose should be given, but you may use your clinical judgment to decide whether an adequate dose was administered before the patient pulled away.

Last reviewed: December 28, 2022

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