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 (1317)

Menveo, in the two-vial presentation that requires reconstitution, is approved for people age 2 months through 55 years. The one-vial formulation that does not require reconstitution was licensed in 2022 for ages 10 through 55 years and should not be used for children younger than age 10. For children beginning the vaccination series at age 2 months the schedule is 4 doses at age 2, 4, 6, and 12 to 15 months. Fewer doses are recommended for children beginning the vaccination series at age 7 months or older. See the Immunize.org document at www.immunize.org/catg.d/p2018.pdf for details.

ACIP recommends the use of Menveo in high-risk children 2 through 23 months of age: children with persistent complement deficiency, including those taking a complement inhibitor such as eculizumab (Soliris) or ravulizumab (Ultomiris), functional or anatomic asplenia, HIV infection, who travel to or reside in regions where meningitis is epidemic or hyperendemic, or who are at risk during a community outbreak attributable to a vaccine serogroup. MenQuadfi (MenACWY-TT) may be used for children at increased risk who are age 2 years and older. These recommendations are summarized in Table 3 of the recommendations published by ACIP in MMWR in 2020: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6909a1-H.pdf.

Last reviewed: March 24, 2024

The manufacturer has not addressed this issue but CDC considers administration of rotavirus vaccine via gastrostomy tube to be acceptable practice. There should be no problem flushing the tube after vaccine has been administered.

Last reviewed: June 7, 2023

Hib vaccine is not routinely recommended for healthy adults 19 years and older, even if the person did not receive Hib vaccine as a child. However, ACIP recommends that one dose of Hib vaccine should be administered to persons who have anatomical or functional asplenia or sickle cell disease or are undergoing elective splenectomy if they have not previously received Hib vaccine. Hib vaccine should be administered 14 or more days before splenectomy if possible. Recipients of a hematopoietic stem cell transplant should be vaccinated with a 3-dose series of Hib vaccine 6 to 12 months after a successful transplant, regardless of vaccination history; at least 4 weeks should separate doses. Hib vaccine is not recommended for adults with HIV infection since their risk for Hib disease is low.

Last reviewed: July 31, 2022

Dengvaxia is a live-attenuated vaccine and is contraindicated in children with severe immunodeficiency or immunosuppression due to underlying disease or therapy, including children with symptomatic HIV infection or CD4+ T-lymphocyte count below 200 per cubic milliliter.

The ACIP recommendations state that Dengvaxia may be used with precaution in people with HIV infection who do not meet the criteria for contraindication, based on an assessment of the person’s risk of vaccination against the risk of dengue and its complications.

Last reviewed: February 16, 2022

There are various requirements for the use of vaccines after reconstitution. Some manufacturers’ package inserts require that the vaccine be used or discarded in varying time frames ranging from 24 hours after reconstitution to immediately after reconstitution. While the specific timeframes are simple to interpret, there can be some confusion as to what the requirement of “immediately” actually means.

CDC considers “immediately” to be the reasonable time it takes to prepare and transport the vaccine to the patient to be administered. This would include any limited documentation that may be related to this process. It is up to the judgment of a provider to determine if a vaccine has not been used in the appropriate time. Some manufacturers have indicated to providers that “immediately” can be up to 30 minutes. The definition of “immediately” varies from manufacturer to manufacturer. Some do not have the data to put forth a general time frame as to what “immediately” means. CDC recommends that the provider contact the manufacturer any time (s)he has any question about whether or not the vaccine has been used in the appropriate time frame.

Last reviewed: December 28, 2022

Yes. Sometimes ACIP makes recommendations that differ from the FDA-approved package insert indications, and this is one of those instances. ACIP recommendations represent the standard of care for vaccination practice in the United States.

Last reviewed: March 31, 2022

It is critical to vaccinate susceptible older children and adults whenever the opportunity arises. With younger children being routinely vaccinated, the chance of being exposed to cases of chickenpox is decreasing. Older children, adolescents, and adults who have not had chickenpox now have a greater chance of remaining susceptible. These older individuals, when they contract chickenpox, are more likely to become seriously ill and have disease complications than younger children.

Last reviewed: May 16, 2023

Depending on conditions, HAV can be stable in the environment for months; freezing does not inactivate (i.e., render non-infectious) HAV. HAV is inactivated by heating foods to temperatures greater than 185°F (85°C) for 1 minute. In addition, HAV on surfaces is inactivated by disinfecting surfaces with a 1:100 dilution of sodium hypochlorite (i.e., household bleach) in tap water.

Adequately chlorinating water through water treatment processes and dilution in public water systems kills HAV. Spas and swimming pools that are adequately treated are not likely to pose a risk for HAV outbreaks.

Last reviewed: June 25, 2023

Yes. CDC recommends that whenever feasible, only one manufacturer’s DTaP product be used for the entire pertussis series, but that vaccinations should not be deferred if the DTaP product previously given is unavailable or unknown.

Last reviewed: July 15, 2023

A pregnant person may administer any vaccine except live, replication-competent smallpox vaccine (ACAM2000, Emergent Biosolutions).

Last reviewed: August 29, 2022

Your best source is to contact your local or state public health agency. You can find contact information by going to www.cdc.gov/rabies/resources/contacts.html.

Last reviewed: August 30, 2020

LAIV can be administered at any time before or after receipt of a blood product. See www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html#, Table 3-5, footnote B.

Last reviewed: June 6, 2023

In a situation where the person’s vaccination status is not aligned with current recommendations at the time of exposure, the person should receive the same postexposure prophylaxis (PEP) regimen as an unvaccinated person. This includes human rabies immune globulin (HRIG) and 4 doses of vaccine (days 0, 3, 7 and 14).

For details on this and other scenarios related to sustaining long term immunogenicity in recipients of the 2-dose rabies primary series, please refer to the figure on page 624 of the May 6, 2022, MMWR at www.cdc.gov/mmwr/volumes/71/wr/pdfs/mm7118a2-H.pdf.

Last reviewed: May 14, 2023

An interim VIS can sometimes be released soon after licensure of the vaccine or after the official vote by ACIP is taken. The interim VIS is not replaced with a final version until the ACIP recommendations have been published and the new VIS has been developed according to legally-mandated procedures.

Last reviewed: June 6, 2023

The meningococcal ACIP recommendations don’t clearly state a minimum interval for MenACWY in this situation. However, the minimum interval for a pediatric MenACWY schedule would presumably be 4 weeks like for other pediatric vaccines on a 2-4-6 schedule. You should try to give a third dose before travel begins.

Last reviewed: March 24, 2024

Check and record storage unit minimum and maximum temperatures for the time since last measurement at the start of each workday. This is a requirement for VFC providers. The minimum and maximum temperatures recorded should be those obtained since the last workday when the minimum and maximum temperatures were reset. If your device does not display minimum and maximum temperatures, then check and record the current temperature a minimum of 2 times (at the start and the end of the workday). This should be done even if there is a temperature alarm at some point during the day.

Last reviewed: July 26, 2023

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

Last reviewed: January 22, 2024

Since the patient is asplenic, the second dose of the primary series of MenACWY should be given at least 8 weeks after the first dose. He will need a dose of MenACWY every 5 years for the rest of his life. The series of MenB (whether Trumenba or Bexsero) should be completed. The first booster dose of MenB will be due one year after completion of the primary series and subsequent booster doses are recommended every 2–3 years for the rest of his life. The same MenB vaccine should be used for all doses in the series, including booster doses. People who receive Trumenba brand MenB vaccine have an option to receive MenABCWY (Penbraya, Pfizer) when both MenACWY and MenB vaccines are due at the same visit, as long as doses of Penbraya are spread out by at least 6 months. The patient has already received the one dose of PCV15 recommended for adults, so no further doses are needed. He also has properly received his first dose of PPSV at least 8 weeks after the dose of PCV15. No additional doses of pneumococcal vaccination are recommended at this time. Based on the patient’s age, only one dose of Hib vaccine is recommended, so no further doses are needed. The patient should receive influenza vaccine annually.

Any of these vaccines can be given at the same appointment, except for PCV15 and PPSV23.

Last reviewed: April 10, 2024

Pneumococcal conjugate vaccine (PCV), Haemophilus influenzae type b (Hib) vaccine, MenACWY, and meningococcal B vaccine should be given at least 14 days before a scheduled splenectomy, if possible. This is done so the patient is protected from these diseases before the spleen is removed; however, doses given during the 14 days before surgery also can be counted as valid. If the doses cannot be given prior to the splenectomy, they should be given as soon as the patient’s condition has stabilized after surgery. If PCV20 is given, pneumococcal polysaccharide vaccine (PPSV23) is not needed; if PCV15 is given, administer a dose of PPSV23 at least 8 weeks after the dose of PCV15 if the patient is age 2 years or older.

Last reviewed: March 24, 2024

Regardless of risk, all children should receive routine vaccination with either PCV15 or PCV20 as age-appropriate. A child age 2 through 18 years with any of the conditions listed below may require additional pneumococcal vaccination depending on their age and prior vaccination status.

The conditions that increase the risk of pneumococcal disease and are indications for additional pneumococcal vaccine doses beyond the routine schedule are broken down into two categories: non-immunocompromising (non-IC) and immunocompromising (IC). Recommendations differ slightly under certain circumstances by IC or non-IC category.

Non-IC conditions include:

  • Cerebrospinal fluid (CSF) leak
  • Chronic heart disease (especially cyanotic congenital heart disease and heart failure)
  • Chronic kidney disease (except as specified in the IC list below)
  • Chronic liver disease
  • Chronic lung disease (including moderate persistent or severe persistent asthma)
  • Diabetes mellitus
  • Cochlear implant

Immunocompromising (IC) conditions include:

  • Kidney disease and on maintenance dialysis
  • Kidney disease with nephrotic syndrome
  • Asplenia or splenic dysfunction
  • Congenital or acquired immunodeficiency, including B-(humoral) or T-lymphocyte deficiency; complement deficiencies, particularly C1, C2, C3, and C4 deficiency; and phagocytic disorders (excluding chronic granulomatous disease)
  • Treatment with immunosuppressive drugs or radiation therapy (including treatment for Hodgkin disease, leukemias, lymphomas, malignant neoplasm, and solid organ transplant)
  • HIV infection
  • Sickle cell disease or other hemoglobinopathies

For timing of vaccination following hematopoietic stem cell transplant, see see www.cdc.gov/vaccines/hcp/acip-recs/general-recs/immunocompetence.html

CDC guidance is available at www.cdc.gov/vaccines/vpd/pneumo/hcp/who-when-to-vaccinate.html.

Immunize.org details all recommendations and options for children with high-risk conditions in its standing order template for pneumococcal vaccination of children and teens (www.immunize.org/wp-content/uploads/catg.d/p3086.pdf) and its shorter resource, Recommendations for Pneumococcal Vaccines use in Children and Teens (www.immunize.org/wp-content/uploads/catg.d/p2016.pdf).

Last reviewed: April 5, 2024

Four hepatitis B (HepB) vaccines are currently licensed in the United States. Three of them contain recombinant hepatitis B surface antigen (HBsAg) produced in yeast cells. PreHevbrio (VBI), is a 3-antigen recombinant hepatitis B vaccine that is derived from mammalian (Chinese hamster ovary) cells.

HepB vaccines are available as HepB-only formulations; two of them are also available in combination with other vaccines. Heplisav-B (Dynavax) and PreHevbrio are both approved only for people 18 years of age and older. Engerix-B (GSK) and Recombivax HB (Merck) are approved for vaccination starting at birth and are available in both pediatric and adult formulations. For the 3-dose series of Engerix-B or Recombivax HB, people 0 through 19 years of age receive a 0.5 mL dose regardless of their height or weight; people 20 years of age and older receive a 1.0 mL dose.

Three combination vaccines that contain HepB are available in the United States. Pediarix (GSK) is approved for children 6 weeks through 6 years of age and contains HepB, DTaP, and inactivated poliovirus (IPV). Twinrix (GSK) is approved for adults 18 years of age and older and contains HepB and inactivated hepatitis A virus (HepA). Vaxelis (MCM Company) is approved for use in children 6 weeks through 4 years of age and contains HepB, DTaP, Hib, and IPV.

Last reviewed: July 21, 2023

The action taken depends on why varicella vaccine was given in the first place. If it was given because the person tested negative for varicella antibody, then the next dose should be varicella vaccine. If the varicella vaccine was given in error (i.e., without serologic testing), then Shingrix should be given.

Last reviewed: March 9, 2022

Peak influenza activity generally occurs in the Northern Hemisphere during December through March, most frequently in January or February. Providers should continue vaccinating patients through spring, as long as there is continued circulation of influenza viruses and they have unexpired vaccine in stock and unvaccinated patients in their office.

Because influenza occurs in many areas of the world during April through September, vaccine should be given to travelers who missed vaccination in the preceding fall and winter. Another late season use of vaccine is for children younger than age 9 years who needed 2 doses of vaccine but failed to get their second dose. For each of these situations, vaccine can be given through the month of June since most injectable influenza vaccine has a June 30 expiration date.

Last reviewed: September 10, 2023

Immunize.org has prepared a document that provides a summary of the ACIP recommendations for use of MenB. The document is available at www.immunize.org/catg.d/p2035.pdf.

Last reviewed: March 24, 2024

Yes. In 2009 ACIP updated its recommendations for use of IPV, partly in response to the availability of newer combination vaccines (e.g., Pentacel) that include an IPV component. The change did not apply to children who had already completed an acceptable 4-dose series of IPV before the updated schedule was published in August 2009. Since August 2009, ACIP has recommended that children receive at least 1 dose of IPV at age 4 through 6 years, even if they have previously received 4 doses. The interval between the next-to-last and last dose should be at least 6 months. This updated recommendation applies to all IPV-containing vaccines, including combination vaccines as well as IPV given as a single product. This means that some children may receive a total of 5 doses, a practice ACIP considers acceptable. This is similar to the recommendation for the last dose in the DTaP series. To view the current polio vaccine recommendations, go to the ACIP recommendations website at www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/polio.html.

Last reviewed: July 15, 2023

ACIP recommends a routine 2-dose HPV vaccine schedule for adolescents who start the vaccination series before the 15th birthday. The two doses should be separated by 6 to 12 months. The minimum interval between doses is 5 calendar months.

A 3-dose schedule is recommended for all people who start the series on or after the 15th birthday and for people with certain immunocompromising conditions (such as cancer, HIV infection, or taking immunosuppressive drugs). The second dose should be given 1 to 2 months after the first dose, and the third dose should be given 6 months after the first dose. The minimum interval between the first and second doses of vaccine is 4 weeks. The minimum interval between the second and third doses of vaccine is 12 weeks. The minimum interval between the first and third dose is 5 calendar months.

If the vaccination series is interrupted, the series does not need to be restarted.

Last reviewed: March 2, 2024

Yes. The effectiveness concerns with antibody-containing blood products (ACBP) do not apply to rotavirus vaccine, since it is administered orally and replication of the vaccine virus occurs in the GI tract, “separate” from the site of the ACBP. Note that the child should be carefully screened for other potential contraindications or precautions to vaccination since administration of immune globulin could indicate immunosuppression.

Last reviewed: June 7, 2023

When elective splenectomy is planned, vaccination with pneumococcal, meningococcal, and Hib vaccines should precede surgery by at least 2 weeks, if possible. If vaccines are not administered before surgery, they should be administered as soon as the person’s condition stabilizes after surgery.

Last reviewed: July 31, 2022

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 or at any interval before or after administration of most other vaccines. One exception is Ty21a oral typhoid vaccine (Vivotif, Emergent Travel Health) and oral cholera vaccine. Oral cholera vaccine should be administered before Ty21a vaccine, and at least 8 hours should separate the cholera vaccine and the first dose of Ty21a.

Last reviewed: December 28, 2022

A history of tetanus disease is not a reason to avoid tetanus-containing vaccines. Tetanus disease does not produce immunity because of the very small amount of toxin required to produce illness. As long as your patient has no other contraindications, she should receive Tdap now. If she has no documentation of prior tetanus vaccination, she should receive a complete 3-dose primary series (dose #1 of Tdap, followed by dose #2 of Td or Tdap 4–8 weeks later, and dose #3 of Td or Tdap 6–12 months after dose #2).

Last reviewed: March 31, 2022

No. Shingles is caused by varicella zoster virus, the same virus that causes chickenpox. A history of shingles based on a healthcare provider diagnosis is evidence of immunity to chickenpox. A person who has had shingles does not need to be vaccinated against varicella. The person should still receive zoster vaccine, however, if it is not contraindicated and the person is age 50 or older or is age 19 or older and immunocompromised.

Last reviewed: May 16, 2023

Both killed and live attenuated measles vaccines became available in 1963. Live attenuated vaccine was used more often than killed vaccine. The killed vaccine was found to be not effective and people who received it should be revaccinated with live vaccine. Without a written record, it is not possible to know what type of vaccine an individual may have received. So, people born during or after 1957 who received killed measles vaccine or measles vaccine of unknown type, or who cannot document having been vaccinated or having laboratory-confirmed measles disease should receive at least 1 dose of MMR. Some people at increased risk of exposure to measles (such as healthcare professionals and international travelers) should receive 2 doses of MMR separated by at least 4 weeks.

Last reviewed: June 19, 2023

No, there is no chronic (long-term) infection. Even the small proportion of people who develop relapsing HAV recover after about 6 months. Once you have had HAV infection and recovered, you cannot get it again.

Last reviewed: June 25, 2023

It is estimated that for every million doses administered, about one (~0.0001%) will result in an anaphylactic reaction following vaccination. The estimate for mRNA COVID-19 vaccines is slightly higher, at 2 to 5 anaphylactic reactions per million vaccinations given. With proper screening, most providers who administer thousands of vaccines in their lifetimes will never see an anaphylactic reaction.

Last reviewed: August 29, 2022

Administration of Dengvaxia to a person who has never been infected with DENV may result in an increased risk of hospitalization and severe dengue illness if they are infected with natural (wild type) DENV for the first time after vaccination. Multiple complex mechanisms likely contribute to increased disease severity during a second DENV infection. The published ACIP recommendation provides a detailed description of these mechanisms at www.cdc.gov/mmwr/volumes/70/rr/pdfs/rr7006a1-H.pdf. In addition, CDC has developed simple illustrations and descriptions to explain this phenomenon at https://www.cdc.gov/dengue/hcp/vaccine/eligibility.html.

In a person who has never been infected with DENV, vaccination with Dengvaxia may “stand in” (immunologically) for the first natural infection, resulting in an increased risk of severe dengue in response to the first natural infection because the immune system responds as if that infection were the “second” infection.

Last reviewed: February 16, 2022

Because of the limited number of serogroups covered by PCV7 (which was used in the United States between 2000 and 2010), CDC recommends that doses of PCV7 should be ignored for the purposes of calculating the current pneumococcal vaccination needs of an older teen or adult patient at increased risk for pneumococcal disease. For example, a person at high risk of pneumococcal disease who received a complete series of PCV7 vaccination in early childhood should follow the vaccination recommendations for someone with their condition who has not received any doses of pneumococcal conjugate vaccine.

Last reviewed: April 5, 2024

Both PCV15 and PCV20 are now recommended as pneumococcal vaccination options for children age 6 weeks and older as well as for older children age 6 through 18 years with certain medical conditions or other risk factors for pneumococcal disease. ACIP no longer recommends PCV13 for children or adults; however, PCV13 may be given as previously recommended if it is the only PCV available and the recipient would otherwise go without vaccination. Pneumococcal polysaccharide vaccine (PPSV23) is recommended as an option for some children age 2 years and older who have certain underlying medical conditions and who have not had (or do not have the option of receiving) PCV20.

Details of the recommendations can be found in the ACIP recommendations at www.cdc.gov/mmwr/volumes/72/wr/pdfs/mm7239a5-H.pdf (for PCV20) and www.cdc.gov/mmwr/volumes/71/wr/pdfs/mm7137a3-H.pdf (for PCV15). These recommendations are to be used in conjunction with CDC clinical considerations for the use of pneumococcal vaccines at: www.cdc.gov/vaccines/vpd/pneumo/hcp/recommendations.html.

A summary of these recommendations can also be found at www.immunize.org/wp-content/uploads/catg.d/p2016.pdf. Immunize.org has developed standing orders for pneumococcal vaccination of children and teens at www.immunize.org/wp-content/uploads/catg.d/p3086.pdf.

Last reviewed: May 24, 2024

Preterm infants should be vaccinated at the same chronological age and according to the same schedule as full-term infants, regardless of birth weight, with the exception of the birth dose of hepatitis B vaccine. Infants weighing less than 2 kg (4.4 lb) whose mothers’ HBsAg status is either positive or unknown should receive HBIG (hepatitis B immune globulin) and hepatitis B vaccine within 12 hours of birth. This dose of hepatitis B vaccine should not be counted as a valid first dose in the series, and it should be repeated at age 1 month. If the preterm infant’s mother’s HBsAg status is negative, the infant’s first dose of hepatitis B vaccine should be withheld until the infant is chronologically 1 month of age or is ready to be discharged from the hospital, whichever occurs first. For more information, see the Vaccination of Preterm Infants section of the ACIP “General Best Practice Guidelines for Immunization”, available at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/special-situations.html.

Last reviewed: August 22, 2020

Yes. The National Childhood Vaccine Injury Act requires that a VIS be given to people of any age before they receive a dose of any vaccine included in the Act. Tetanus and diphtheria toxoids (and pertussis vaccine) are included in the Act. If the patient is unaccompanied and unable to clearly read and understand the information in the VIS (e.g., the patient is unconscious), this should be noted in the patient’s chart.

Last reviewed: June 6, 2023

If the vaccine cold chain is broken, the ambient room temperature is useful information in helping determine how to handle the compromised vaccine. Do not remove the calibrated thermometer from the refrigerator or freezer to measure the room temperature. A standard household thermometer in the room is fine for this purpose.

Last reviewed: July 26, 2023

No. The ACIP meningococcal serogroup B vaccine recommendations state that the same vaccine (either Bexsero by GSK or Trumenba by Pfizer) must be used for all doses in the MenB series, including booster doses. If the brand of a previous dose is unavailable or cannot be determined, restart the primary series with the available brand. The pentavalent MenABCWY product Penbraya (Pfizer) contains MenB-Fhbp (Trumenba) as its MenB component; therefore, Penbraya should only be used in series with Trumenba.

Last reviewed: March 24, 2024

Shingrix may be administered to people who have previously received 2 doses of varicella vaccine. Compared to people who have had chickenpox, the risk of zoster among recipients of varicella vaccine (which contains a live-attenuated strain of varicella virus) is much lower, but is still possible.

Last reviewed: March 9, 2022

Not necessarily. People who have documentation of receiving live measles vaccine in the 1960s do not need to be revaccinated. People who were vaccinated prior to 1968 with either inactivated (killed) measles vaccine or measles vaccine of unknown type should be revaccinated with at least one dose of live attenuated measles vaccine. This recommendation is intended to protect people who may have received killed measles vaccine which was available in the United States in 1963 through 1967 and was not effective. People vaccinated before 1979 with either killed mumps vaccine or mumps vaccine of unknown type who are at high risk for mumps infection (such as people who work in a healthcare facility) should be considered for revaccination with 2 doses of MMR vaccine.

Last reviewed: June 19, 2023

CDC’s clinical guidance for the use of COVID-19 vaccines states that any vaccine may be given on the same day or any day before or after COVID-19 vaccination, at a different anatomic site. According to the CDC’s “General Best Practice Guidelines for Immunization”, simultaneously administering all vaccines for which a person is eligible at the time of a visit increases the probability that a person will be fully vaccinated by the appropriate time.

IIV4 and RIV4 can be administered without regard to the timing of other live or inactivated vaccines. Injectable vaccines should be administered in separate anatomic sites when given on the same day.

LAIV4 may be given on the same day as any other live or inactivated vaccines. However, if two live vaccines are not given on the same day, they should be separated by at least 4 weeks.

There are now several vaccines containing nonaluminum adjuvants recommended for adults (including Shingrix [zoster], Heplisav-B [HepB], Arexvy [RSV] and Fluad [aIIV4, influenza]). Because of the limited data on the safety of simultaneous administration of two or more vaccines containing nonaluminum adjuvants and the availability of nonadjuvanted influenza vaccine options, ACIP advises that selection of a nonadjuvanted influenza vaccine may be considered in situations in which influenza vaccine and another vaccine containing a nonaluminum adjuvant are to be administered at the same visit. However, influenza vaccination should not be delayed if a specific vaccine is not available.

Last reviewed: September 10, 2023

The original COVID-19 vaccines all targeted the spike protein of the original SARS-CoV-2 virus. The current vaccines target the spike protein of a more recently circulating strain, known as the Omicron XBB.1.5 sublineage. The update is intended to boost production of antibodies that protect more effectively against disease caused by currently circulating Omicron subvariants.

The process of updating the strain without changing anything else is similar to the seasonal strain changes made for influenza vaccinations each year; FDA does not require manufacturers to repeat the large-scale clinical trials necessary for the original products before authorizing updated vaccines. Vaccine safety, side effects, and risk of allergic reactions are expected to be comparable to the original vaccines of the same brand and dose. As with seasonal influenza vaccines, future COVID-19 vaccines can continue to be updated when needed, as the circulating viruses evolve.

Last reviewed: March 19, 2024

Coverage levels for HPV vaccine are improving but are still inadequate. Results from CDC’s 2022 National Immunization Survey-Teen (NIS-Teen) indicate that for the first time since 2013, HPV vaccination initiation did not increase among adolescents age 13 through 17 years. HPV vaccination initiation actually fell among adolescents insured by Medicaid and remained lowest among the uninsured. The Vaccines for Children (VFC) program ensures access to HPV and other routine vaccines for adolescents who are uninsured or Medicaid-eligible at no cost. It is important that families are aware of this entitlement and the importance of HPV vaccination.

In 2022, 76% of adolescents had received at least 1 dose of HPV vaccine and 62.6% were up to date with HPV vaccination. A summary of the 2022 NIS-Teen survey and trends are available at www.cdc.gov/mmwr/volumes/72/wr/mm7234a3.htm.

Providers can improve uptake of this life-saving vaccine in several ways. First, studies show that missed opportunities are occurring. Some clinics address this by routinely starting the 2-dose vaccination series as early as possible, at age 9, giving them more chances to complete the series on time before age 13. A different strategy to improve uptake is by ‘bundling’ the recommendations for all adolescent vaccines at the first preteen visit. CDC recommends the following discussion starter: “Now that your child is 11, they need three vaccines to help protect against meningitis, HPV cancers, and whooping cough. We’ll give these shots during today’s visit. Do you have any questions about these vaccines?”

One of the main reasons parents give researchers for not vaccinating their adolescents is that the HPV vaccine was not recommended to them by their child’s healthcare provider. CDC urges healthcare providers to strongly and consistently recommend HPV vaccine, especially when patients are age 11 or 12 years. CDC’s “Talking to Parents about HPV Vaccine,” available at www.cdc.gov/hpv/hcp/for-hcp-tipsheet-hpv.pdf can help providers with these conversations.

For more detailed information about HPV vaccination strategies for providers, visit www.cdc.gov/hpv/hcp/boosting-vacc-rates.html and www.cdc.gov/vaccines/partners/routine-immunizations-lets-rise.html.

Last reviewed: March 2, 2024

Yes. Doses of any quadrivalent meningococcal vaccine given before 10 years of age should not be counted as part of the adolescent MenACWY series. If a child received a dose of either MPSV4 or MenACWY before age 10 years, they should receive a dose of MenACWY at 11 or 12 years and a booster dose at age 16.

Last reviewed: March 24, 2024

Although the gluteus muscle is not a recommended site for vaccination, in general, a dose given there can be considered valid. The exceptions to this general rule are hepatitis B and rabies vaccines, so the hepatitis B vaccine should not be counted in this situation. The hepatitis B vaccine can be repeated immediately. See the Advisory Committee on Immunization Practice’s (ACIP) “General Best Practices Guidelines for Immunization”, available at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/administration.html.

Last reviewed: December 28, 2022

No. Tdap should be administered as soon as possible.

Last reviewed: March 31, 2022

You are interpreting the recommendations correctly, and age is an important factor in this issue. The recommendation for Hib vaccination for asplenia applies to persons of all ages. The recommendation for Hib vaccination for immunoglobulin deficiency applies only to children 12 through 59 months of age.

Last reviewed: July 31, 2022

No. It is the volume of the dose, not the antigen content, that is important. People 20 years and older should always receive a 1.0 mL dose of either Engerix-B or Recombivax HB when using those products. Likewise, people younger than 20 years should always receive a 0.5 mL dose of the pediatric formulation of either Engerix-B or Recombivax HB.

Last reviewed: July 21, 2023

No. Receipt of one dose of live zoster vaccine is not proof of varicella immunity. According to CDC, 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. If a healthcare employee has received a dose of live zoster vaccine in the past but has no other evidence of immunity to varicella, the live zoster dose can be considered the first dose of the 2-dose varicella series. Note that recombinant zoster vaccine (RZV, Shingrix) cannot be counted as the first dose in a 2-dose varicella vaccination series because Shingrix is not licensed and has not been evaluated for the prevention of primary varicella infection (chickenpox).

Last reviewed: May 16, 2023

Vaccination with the full series of hepatitis A vaccine (HepA) is the best way to prevent HAV infection. Immune globulin (IG) also can be used for short-term protection in certain situations.

Last reviewed: June 25, 2023

The rotavirus vaccine dose given by the intramuscular route is not valid and should be repeated by the oral route as soon as possible. In a review of such rotavirus vaccine administration errors, there usually were not adverse reactions, and those documented were limited to local reactions and general, brief irritability. Please see www.cdc.gov/mmwr/pdf/wk/mm6304.pdf, page 81, for more information.

Please take steps to ensure that such vaccine administration errors are avoided in the future. This event should be reported to the Vaccine Adverse Event Reporting System at https://vaers.hhs.gov even if an adverse reaction does not result from it.

Last reviewed: June 7, 2023

Pentacel (DTaP-IPV/Hib) inadvertently administered to children six years of age and older is considered a vaccine administration error. However, none of the vaccine components need to be repeated.

Last reviewed: July 15, 2023

The antibiotics, of which there are trace amounts in some influenza vaccines, are neomycin, gentamicin, and polymyxin B. You should check each product’s package insert information to see which, if any, antibiotics are listed.  Links to all current vaccine package inserts for vaccines are available at www.immunize.org/fda/.

Last reviewed: October 4, 2022

CDC has established strict accuracy criteria for the laboratory tests considered acceptable proof of past DENV infection before vaccination of a child.

No test is perfectly accurate: wrong results lead to different types of risk. A false negative test result means a child who is at increased risk of severe dengue would not be protected by vaccination. A false positive test means a child who was not at high risk of severe dengue would be vaccinated, potentially increasing the child’s risk of severe dengue if the child experiences a subsequent DENV infection.

All dengue IgG tests for pre-vaccination screening must have a minimum specificity of at least 98% to minimize the chance of misclassifying a person who should have a true negative test result as positive. This high specificity minimizes the risk of vaccinating a person who should not be vaccinated.

Pre-vaccination screening tests must also have a sensitivity of at least 75% to accurately identify a high proportion of children and adolescents with past dengue virus infections who can benefit from vaccination.

Acceptable laboratory confirmation of previous dengue virus infection can be obtained by:

  • Evidence of prior acute dengue virus infection with
    • Positive dengue RT-PCR test result, or
    • Positive dengue NS1 antigen test result
  • OR, positive results on BOTH of the following anti-dengue virus IgG antibody tests in a two-step testing algorithm:
    • EUROIMMUN Anti-Dengue Virus NS1 Type 1-4 ELISA (IgG) and
    • CTK BIOTECH OnSite Dengue IgG Rapid Test

Visit www.cdc.gov/dengue/vaccine/hcp/testing.html. for additional information about laboratory testing requirements for vaccination with Dengvaxia. As additional tests are evaluated and approved as acceptable, information will be updated by CDC.

Vaccinators are encouraged to use the CDC prevaccination checklist to evaluate patient eligibility: www.cdc.gov/dengue/resources/DVBD_FS_Vaccination_Checklist-508.pdf.

Last reviewed: February 16, 2022

PPSV23 has only limited indications in children age 2 through 18 years who have not had PCV20 and are at high risk for serious pneumococcal infection due to the presence of a specific non-immunocompromising (non-IC) or immunocompromising (IC) medical condition.

If PCV20 is not offered, PPSV23 is recommended as an option to be administered to a child age 2 years or older at least 8 weeks following completion of PCV vaccination with PCV13 or PCV15. If a child has an immunocompromising condition and PPSV23 is used, a dose of PCV20, or a second dose of PPSV23, should be given 5 years later.

Immunize.org details all recommendations and pneumococcal vaccine options for children with high-risk conditions in its standing order template for pneumococcal vaccination of children and teens (www.immunize.org/wp-content/uploads/catg.d/p3086.pdf) and its shorter resource, Recommendations for Pneumococcal Vaccines Use in Children and Teens (www.immunize.org/wp-content/uploads/catg.d/p2016.pdf).

Last reviewed: May 24, 2024

While CDC states that it is acceptable to coadminister influenza and RSV vaccines, there are issues that should be considered before deciding to coadminister these vaccines to a specific patient. Data informing simultaneous administration with influenza vaccines is limited and evolving. Data on coadministration of RSV and influenza vaccines showed that antibody titers were somewhat lower with coadministration; however, the clinical significance of this is unknown. In addition, administering RSV vaccine with one or more other vaccines at the same visit might increase local or systemic reactogenicity. Data are available for coadministration of RSV and influenza vaccines, and evidence is mixed regarding increased reactogenicity.

ACIP advises that when deciding whether to coadminister other vaccines with an RSV vaccine, consider whether the patient is up to date with currently recommended vaccines, the feasibility of the patient returning for additional vaccine doses, risk for acquiring vaccine-preventable disease, vaccine reactogenicity profiles, and patient preferences.

Additional considerations for coadministration of influenza and other vaccines are available in the 2023 ACIP RSV vaccine recommendations for older adults, page 798: www.cdc.gov/mmwr/volumes/72/wr/pdfs/mm7229a4-H.pdf.

Yes, they should receive a booster dose at age 16. A booster dose of MenACWY is recommended at age 16 years even if 2 (or more) doses of MenACWY vaccine were received before age 16 years. First-year college students living in a residence hall who have not received a dose of MenACWY on or after age 16 years, should also be vaccinated.

Last reviewed: March 24, 2024

If Tdap is administered earlier in pregnancy, it should not be repeated between 27 and 36 weeks’ gestation; only one dose is recommended during each pregnancy.

Last reviewed: October 31, 2023

CDC recommends that refrigerator and freezer temperature logs be kept for at least 3 years. See page 10 of the Vaccine Storage and Handling Toolkit, available at www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf. The reasoning is that it is useful to be able to look back at the record to help determine if a unit is developing a problem.

Individual state Vaccines For Children (VFC) programs may have additional requirements for retaining temperature logs. You should contact your state program for this information. Contact information for state immunization programs is available at www.immunize.org/coordinators.

Last reviewed: July 26, 2023

ACIP does not recommend routine PCV vaccination of healthy children 60 months of age or older. If there is a school requirement, the simplest solution is to give the child one dose of either PCV15 or PCV20 now. However, health insurance may not pay for this dose. For more information on the ACIP recommendations for pneumococcal vaccination of children, go to CDC’s summary of pneumococcal vaccine recommendations: www.cdc.gov/vaccines/vpd/pneumo/hcp/who-when-to-vaccinate.html.

Last reviewed: April 5, 2024

Explain to the parent that vaccination starting at 11 or 12 years will provide the best protection possible long before the start of any kind of sexual activity. It is standard practice to vaccinate people before they are exposed to an infection, as is the case with measles and the other recommended childhood vaccines. Similarly, we want to vaccinate children before they get exposed to HPV. Studies of HPV vaccine indicate that younger adolescents respond better to the vaccine than older adolescents and young adults. Healthy children vaccinated at this age will need only 2 doses of vaccine rather than 3 doses if vaccinated at an older age. Finally, numerous research studies have shown that getting the HPV vaccine does not make kids more likely to be sexually active or start having sex at a younger age.

Last reviewed: March 2, 2024

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