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.

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Results (1374)

Yes. Other inactivated and/or live virus vaccines can be administered at the same time as HepA vaccine, but should be given at a different anatomical site, if possible. If given in the same muscle, separate the injections by a minimum distance of 1 inch.

Last reviewed: June 25, 2023

A booster dose should be given to first-year college students, regardless of age, who are or will be living in a residence hall if the previous dose was given before the age of 16 years or if their most recent dose (given after the 16th birthday) was not given within the past 5 years.

Last reviewed: November 15, 2024

There is no minimum period to wait to correct your error. If you had immediately realized that you had mistakenly given the father-to-be Td instead of Tdap, you could have given him the needed Tdap dose at the same visit at which you gave him the erroneous Td dose.

Last reviewed: March 31, 2022

No. Mesalamine (mesalazine) is a non-steroidal anti-inflammatory drug. It is not immunosuppressive, so its use would not place a person at increased risk of invasive pneumococcal disease.

Last reviewed: November 13, 2024

Yes. It is especially important to vaccinate during pregnancy because of the increased risk for influenza-related complications during pregnancy and the baby’s increased risk of influenza-related illness and hospitalizations during the first 6 months of life.

Influenza vaccination during pregnancy reduces mothers’ risk of influenza illness, preterm labor, and their infants’ risk of influenza and influenza-related hospitalization in the first 6 months of life.

Vaccination can occur in any trimester, including the first. Only inactivated or recombinant influenza vaccines may be given during pregnancy. FluMist (LAIV), a live vaccine, should not be given during pregnancy.

Last reviewed: August 11, 2024

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

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

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

Last reviewed: August 25, 2024

CDC states that no additional medical documentation is required before vaccination.  The patient’s affirmation of moderate or severe immunocompromise is sufficient: vaccinators should not deny COVID-19 vaccination to a person due to lack of documentation.

Last reviewed: November 16, 2024

Findings of this study discourages the prophylactic use of paracetamol (similar to acetaminophen) prior to or immediately following vaccination. Acetaminophen can be used to treat pain or fever if it should occur following vaccination. ACIP’s “General Best Practices Guidelines for Immunization” state: “Evidence does not support use of antipyretics before or at the time of vaccination; however, they can be used for the treatment of fever and local discomfort that might occur following vaccination. Studies of children with previous febrile seizures have not demonstrated antipyretics to be effective in the prevention of febrile seizures.” For more information on this issue, see Methods for Alleviating Discomfort and Pain Associated with Vaccination at www.cdc.gov/vaccines/hcp/imz-best-practices/vaccine-administration.html.

Last reviewed: December 28, 2022


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Last reviewed: April 6, 2023

Available data do not suggest a benefit from administering additional HepB vaccine doses to infants who have not attained anti-HBs of mIU/mL or higher following receipt of two complete HepB series. HBsAg-positive infants should be referred for appropriate follow-up with a physician who specializes in evaluating infants with liver disease.

Last reviewed: January 17, 2025

No. Antiretroviral treatment for HIV may improve immune response to vaccination; however, vaccination for shingles does not have to be delayed in order to achieve viral suppression, especially if this will significantly delay vaccine administration. Patients with advanced HIV should receive RZV, because the risk of shingles is further increased in the setting of such immune compromise.

Last reviewed: March 9, 2022

No. A measles-containing vaccine administered more than 4 days before the first birthday should not be counted as part of the series. MMR should be repeated when the child is age 12 through 15 months (12 months if the child remains in an area where disease risk is high). The second dose should be administered at least 28 days after the first dose.

Last reviewed: June 19, 2023

The ACIP’s varicella vaccine recommendations state that no adverse events associated with the use of salicylates after varicella vaccination have been reported, however, the vaccine manufacturer recommends that vaccine recipients avoid using salicylates for 6 weeks after receiving varicella vaccines because of the association between aspirin use and Reye syndrome after varicella disease (chickenpox). Vaccination with subsequent close monitoring should be considered for children who have rheumatoid arthritis or other conditions requiring therapeutic aspirin. The risk for serious complications associated with aspirin is likely to be greater in children in whom natural varicella develops than it is in children who receive the vaccine containing attenuated varicella zoster virus. In other words, the benefit of varicella vaccine likely outweighs the theoretical risk of Reye syndrome. See the ACIP varicella recommendations at www.cdc.gov/mmwr/PDF/rr/rr5604.pdf, page 29.

Last reviewed: May 16, 2023

You should withhold further HPV vaccine until she is no longer pregnant. After the pregnancy is completed, administer the remaining doses of the series using the usual 2- or 3-dose schedule (depending on the age at initiation of the series).

Last reviewed: March 2, 2024

Yes. ACIP recommends a dose of Tdap be given to all adults, including those age 65 years or older.

Last reviewed: March 31, 2022

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/imz-best-practices/vaccine-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

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

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 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 age-appropriate brand. CDC recommends the same brand 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: November 16, 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

This question has arisen more frequently since the introduction of the RSV preventive antibody, nirsevimab (Beyfortus, Sanofi), which has an injection volume of 1 mL for infants younger than 8 months who weigh 5 kg or more at the time of immunization. High risk children entering their second RSV season require a Beyfortus dose volume of 2 mL. Beyfortus is often administered at a routine visit when other infant immunizations are due.

There is no specific guidance to not exceed 1 mL in one muscle. In fact, there is no clear standard of practice and reference texts vary in guidance. Facilities or health systems may have medication policies/procedures that outline guidance for their staff. Professional judgement is needed when administering intramuscular medications or immunizations to people, including children, because muscle size varies from person to person.

CDC experts suggest a range of volume, depending upon the muscle injected. For the deltoid, the typical volume injected is 0.5 mL (maximum: 2 mL). For the vastus lateralis (the thigh): the typical volume that may be injected is 1–4 mL (maximum: 5 mL). Infants and toddlers fall at the lower end of these ranges, whereas adolescents and adults generally fall on the higher end of the range.

If more than 1 mL of volume needs to be injected into the thigh, that can be done while staying well within the acceptable range. Use of combination vaccines, when indicated and available, can decrease injection volume.

Last reviewed: January 20, 2025

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: January 17, 2025

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 should receive 1 additional 2024–2025 Formula COVID-19 vaccine dose 6 months (minimum interval 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: November 16, 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

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

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 should receive an additional 2024–2025 Formula COVID-19 dose of any brand in 6 months (minimum interval 2 months), followed by additional doses (minimum interval 2 months apart) as needed, based on your clinical judgment, his preference, and his individual circumstances. 

Last reviewed: November 16, 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: January 17, 2025

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

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

This page was updated on .

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