Ask the Experts: All Questions

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

How to Find Your Answer

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

  • Some filter options may become disabled as you narrow your selections.
  • Filters are easily added and removed. Click or tap on the X to remove individual filters or choose “Reset All Filters” to remove all filters.
Results (1317)

The most important factor in preventing outbreaks is annual vaccination of all residents and staff who work at facilities such as nursing homes, assisted living facilities, and other group living situations. Groups that should be targeted include physicians, nurses, and other personnel working or volunteering in hospitals and outpatient settings who have contact with high-risk patients in all age groups, and providers of home care to high-risk people (for example, visiting nurses, therapists, and volunteers).

Last reviewed: September 10, 2023

In 2020, in response to the COVID-19 pandemic, CDC temporarily recommended additional infection control steps to ensure the safety of people in vaccination clinics, including universal wearing of face masks to reduce the risk of transmission. In the setting of widely available and effective COVID-19 vaccines and treatments, CDC resumed recommending standard pre-pandemic infection control practices during vaccination. The use of face masks to protect patients or staff from respiratory viruses while administering vaccinations should be based on professional judgment in the specific circumstances and/or institutional policy.

Last reviewed: December 28, 2022

Both vaccines should be stored at refrigerator temperature and protected from light. Do not administer the vaccine if it has been frozen or exposed to freezing temperatures.

Last reviewed: June 7, 2023

Hib vaccination is contraindicated for individuals known to have experienced a severe allergic reaction (anaphylaxis) to a vaccine component or following a prior dose. Hib-containing vaccines are contraindicated for children younger than 6 weeks of age because of the potential for development of immunologic tolerance. The PedvaxHIB vial stopper contains dry natural rubber which could produce an allergic reaction in children with severe allergy to latex.

Vaccination should be delayed for children with moderate or severe acute illnesses. Minor illnesses, such as a mild upper respiratory infection are not a reason to delay vaccination.

Contraindications and precautions for the use of Pentacel (DTaP-IPV/Hib) and Vaxelis (DTaP-Hib-HepB-IPV) are the same as those for their individual component vaccines.

Last reviewed: July 31, 2022

Yes, Dengvaxia may be given at the same visit with any live or non-live vaccines that are also indicated for the patient.

If Dengvaxia is not administered on the same day as another live vaccine, the two vaccines should be separated by at least 4 weeks to minimize the potential risk of interference.

Last reviewed: February 16, 2022

Yes. The updated ACIP recommendations for the use of Tdap vaccine state that Tdap or Td may be used in any situation where Td only was previously recommended. The updated guidelines are available at www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6903a5-H.pdf.

Last reviewed: March 31, 2022

Live varicella vaccine should not be given to anyone known to be pregnant. If a person who is planning to become pregnant in the future comes in for a visit or an annual exam, the varicella history should be obtained and if indicated, 2 doses of vaccine should be given, spaced 4 to 8 weeks apart. Vaccine recipients capable of becoming pregnant should be counseled to avoid pregnancy for one month following each dose of varicella vaccine. A person who is inadvertently vaccinated while pregnant or becomes pregnant within a month of vaccination should be counseled about the theoretical risk to the fetus; however, it should not be considered a reason to terminate a pregnancy. Pregnant people should be assessed for evidence of varicella immunity and if non-immune, should receive the first dose of varicella vaccine following completion of the pregnancy and prior to hospital discharge. A second dose should be given 4 to 8 weeks later.

Last reviewed: May 16, 2023

All children should receive 2 doses of HepA vaccine beginning at age 1 year (i.e., 12–23 months). The 2 doses in the series should be administered at least 6 months apart. Any child age 2 through 18 years not previously vaccinated should be vaccinated. For a copy of the ACIP recommendations on hepatitis A, go to www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.

Last reviewed: June 25, 2023

Yes. Although it is preferable to use the same manufacturer’s DTaP vaccine for all of the doses in the series, you can give either Kinrix or Quadracel as the fifth dose of DTaP and fourth dose of IPV at age 4 through 6 years if the previous brand is unknown or if Kinrix or Quadracel is the only product stocked.

Last reviewed: July 15, 2023

Yes, unless they have a contraindication to vaccination.

Last reviewed: March 9, 2022

A history of having had measles is not sufficient evidence of measles immunity. A positive serologic test for measles-specific IgG will confirm that the person is immune and is not at risk of infection regardless of the multiple myeloma. Multiple myeloma is a hematologic cancer and is considered immunosuppressive so MMR vaccine is contraindicated in this person.

Last reviewed: June 19, 2023

Disposable syringes are meant for administration of vaccines, not for storage. CDC recommends that vaccines that have been drawn into syringes by the provider be discarded at the end of the clinic day if unused. Manufacturer-filled syringes that have not been activated (i.e., have not had the needle guard removed or a needle attached) may be kept and used until their expiration date. A manufacturer-filled syringe does not contain a preservative to help prevent the growth of microorganisms. Once the sterile seal has been broken, the vaccine should be used or discarded by the end of the workday.

Last reviewed: July 26, 2023

MenB is not specifically recommended for immunosuppressed people. However, after discussing the pros and cons of vaccination (also known as shared clinical decision-making), people age 16 through 23 years who are not at increased risk may receive routine MenB vaccination with either a 2-dose series of Bexsero (MenB-4C) 4 weeks apart, or a 2-dose series of Trumenba (MenB-FHbp) 6 months apart. Penbraya (MenABCWY, Pfizer) is also an option if both Trumenba and MenACWY vaccines are due at the same visit and it has been at least 6 months since the most recent dose of Penbraya.

Last reviewed: March 24, 2024

Both RSV vaccines (Arexvy, Abrysvo) are administered by the intramuscular route.

Last reviewed: January 22, 2024

For adults 65 years and older with no prior pneumococcal vaccination or whose previous vaccination history is unknown, you have two options:

  • One dose of PCV20 alone, or
  • One dose of PCV15 followed by a dose of PPSV23 one year later (if the patient has an immunocompromising medical condition, cochlear implant or cerebrospinal fluid leak consider giving PPSV23 as soon as 8 weeks later).
Last reviewed: April 5, 2024

No. You do not need to expel the air pocket. The air will be absorbed. This is not true for syringes that you fill yourself; you should expel air bubbles from these syringes prior to vaccination to the extent that you can do so.

Last reviewed: December 28, 2022

This child should receive the dose recommended for his age at the time of the vaccination visit. At age 11 years, an age-appropriate single dose of either Pfizer-BioNTech or Moderna mRNA vaccine is recommended. If the patient arrives in your clinic after turning 12 years old, the 2023-2024 Formula Novavax protein subunit vaccine is also an option. If using the Novavax product, a previously unvaccinated person requires two doses, given 3 to 8 weeks apart, as a primary series.

Last reviewed: March 19, 2024

Use of either Kinrix (GSK) or Quadracel (Sanofi) in a child younger than age 4 years is off-label and is not recommended. You should take measures to prevent this error in the future. The minimum age for the fifth dose of the DTaP series is 4 years, and the minimum age for the final dose of IPV is also 4 years, so this dose of Kinrix is not valid. Both the DTaP and IPV will need to be repeated after the child’s fourth birthday.

For detailed information, see CDC’s useful table “Recommended and Minimum Ages and Intervals Between Doses of Routinely Recommended Vaccines” at www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/A/age-interval-table.pdf.

Last reviewed: July 15, 2023

Yes. Menveo (MenACWY-CRM) or MenQuadfi (MenACWY-TT) may be given simultaneously with PCV or at any interval before or after receipt of PCV.

Last reviewed: March 24, 2024

Adverse reactions following Hib conjugate vaccines are not common. Swelling, redness, or pain have been reported in 5%–30% of recipients and usually resolve within 12–24 hours. Systemic reactions such as fever and irritability are infrequent.

All serious adverse events that occur after receipt of any vaccine should be reported to the Vaccine Adverse Event Reporting System (VAERS) (https://vaers.hhs.gov).

Last reviewed: July 31, 2022

You should continue where the patient left off and complete the series. You never have to restart the series.

Last reviewed: February 16, 2022

ACIP recommends that patients needing prophylaxis against tetanus always be given either Td or Tdap rather than TT, as long as there is no contraindication to the other vaccine components. If it’s already been given and the person had not yet received Tdap as an adolescent or adult, you should make certain that he gets Tdap as soon as feasible. If he had received Tdap previously, he can wait until the next scheduled booster dose is due to get his routine Td or Tdap booster.

Last reviewed: March 31, 2022

Yes. CDC’s “General Best Practice Guidelines for Immunization” advise that non-live vaccines, such as Shingrix, can be administered concomitantly, at different anatomic sites, with any other live or non-live vaccine, including the vaccines you listed, as well as COVID-19 vaccines. They should be given as separate injections, not combined in the same syringe.

Last reviewed: March 9, 2022

People with a reliable history of varicella can be considered to be immune. A reliable history for healthcare personnel consists of (1) a healthcare provider’s diagnosis of varicella or verification of history of varicella disease; (2) a healthcare provider’s diagnosis of herpes zoster or verification of a history of herpes zoster; or (3) laboratory evidence of immunity or laboratory confirmation of disease. Immunity following disease or vaccination is probably life-long. More than one primary infection with varicella is unusual.

Last reviewed: May 16, 2023

No. The minimum interval between dose #1 and #2 of HepA vaccine is 6 calendar months, not 24 weeks.

Last reviewed: June 25, 2023

If a patient or family member cannot remember if the patient received influenza vaccine this season and no record is available, proceed with administering influenza vaccine, even if it might mean an extra dose is given. When a patient reports that they HAVE received influenza vaccine but does not have written documentation, ACIP states that in the specific case of influenza (and pneumococcal polysaccharide) vaccination, patient self-report of being vaccinated can be accepted as evidence of vaccination.

Last reviewed: September 10, 2023

You can find information on latex in vaccine packaging in Appendix B of CDC’s Epidemiology and Prevention of Vaccine-Preventable Diseases (the “Pink Book”) at www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/latex-table.pdf.

Last reviewed: August 29, 2022

Studies indicate that immunologic memory remains intact for at least 30 years and confers protection against clinical illness and chronic HBV infection, even though anti-HBs levels that once measured adequate might become low or decline below detectable levels. If exposed to HBV, people whose immune systems are competent will mount an anamnestic response and develop protective anti-HBs. Studies are on-going to assess whether booster doses of HepB will be needed in the future.

Last reviewed: July 21, 2023

You have two options. You can test for immunity or you can just give 2 doses of MMR at least 4 weeks apart. There is no harm in giving MMR vaccine to a person who may already be immune to one or more of the vaccine viruses. If you or the patient opt for testing, and the tests indicate the patient is not immune to one or more of the vaccine components, give your patient 2 doses of MMR at least 4 weeks apart. If any test results are indeterminate or equivocal, consider your patient nonimmune. ACIP does not recommend serologic testing after vaccination because commercial tests may not be sensitive enough to reliably detect vaccine-induced immunity.

Last reviewed: June 19, 2023

ACIP does not recommend routine MenB vaccination for travel to countries in sub-Saharan Africa or to other countries for which MenACWY vaccine is recommended. Meningococcal disease in these areas is generally not caused by serogroup B.

Last reviewed: March 24, 2024

With the exception of COVID-19 vaccines, vaccines in multidose vials (MDVs) that do not require reconstitution contain preservatives and can be used through the expiration date printed on the label as long as the vaccine is not contaminated, unless indicated otherwise by the manufacturer. For example, inactivated polio vaccine in an MDV can be used through the expiration date on the vial. For some vaccines, the manufacturer specifies that once the MDV has been entered or the rubber stopper punctured, the vaccine must be used within a certain number of days. This is commonly referred to as the “beyond-use date” (BUD). Any vaccine not used within the BUD should be discarded. Specific information regarding the BUD can be found in the product information. For example, the package insert for some inactivated influenza vaccine indicates once the stopper of the MDV has been pierced, the vial must be discarded within 28 days. Package inserts for vaccines can be found at www.immunize.org/fda.

Be careful to follow current guidance from the manufacturer and CDC for how long an MDV of COVID-19 vaccine may be used after puncturing the vial. The COVID-19 vaccine MDVs do not contain preservatives and must be used within hours; specific times vary by product.

Last reviewed: July 26, 2023

Hib vaccine should be maintained at refrigerator temperature between 2°C and 8°C (36°F and 46°F). Manufacturer package inserts contain additional information and can be found at www.immunize.org/packageinserts. For complete information on best practices and recommendations please refer to CDC’s Vaccine Storage and Handling Toolkit at www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf.

Last reviewed: July 31, 2022

It is not wrong to expel the air from syringes filled by manufacturers, but typically it is such a small amount of air (0.2cc–0.3cc) that it is CDC’s opinion that it would not cause a problem. When the syringe is inverted during an injection, that small amount of air would typically just clear the medication from the needle. This is based on the recommendation that when the Z-track method is used for intramuscular injection of irritating medication (e.g., iron preparations), the guidance is to leave 0.2cc–0.3cc in the syringe to be sure that all of the medication leaves the needle and is not tracked back through subcutaneous tissue as the needle is withdrawn. While the Z-track injection technique is not recommended for vaccine administration, the Z-track method demonstrates the acceptability of leaving a very small amount of air in the syringe for intramuscular injections.

CDC does, however, recommend that when drawing vaccine from a vial into a regular syringe, the air be expelled because the amount of air drawn into the syringe may be larger than the amount in a manufacturer-filled syringe. Expelling the air is part of general medication guidelines for drawing medication into a syringe.

Last reviewed: December 28, 2022

Yes. It is acceptable to administer either RSV vaccine at the same time as other recommended vaccines, in accordance with CDC’s general best practice guidelines for immunization. This is especially important if you are concerned an unvaccinated patient will not return or if the patient’s immediate risk is high (such as when seasonal influenza, RSV, and COVID-19 are circulating). Coadministration might increase short-term side effects (greater reactogenicity), such as fever, soreness, body aches, or headache, especially when administering more than one vaccine containing a non-aluminum adjuvant designed to enhance the immune response. While these side effects are not unsafe, they may be unpleasant for a day or two. If you are confident that a patient will return, the patient may prefer to separate the administration of vaccines that are less time-sensitive (e.g., shingles vaccine) to reduce the likelihood of uncomfortable side effects. There is no specific minimum interval between non-live vaccines, so separation by just a few days is acceptable, if desired.

Last reviewed: January 22, 2024

ACIP recommends vaccination with 3 doses of HPV vaccine for people age 9 through 26 years with primary or secondary immunocompromising conditions that might reduce cell-mediated or humoral immunity. Examples include B lymphocyte antibody deficiency, T lymphocyte complete or partial defects, HIV infection, malignant neoplasm, transplantation, autoimmune disease, or immunosuppressive therapy. In these circumstances, the 3-dose series is recommended even for those who initiate vaccination at age 9 through 14 years when the routine recommendation is for a 2-dose series.

Last reviewed: March 2, 2024

Yes. You must initiate the series while the recipient is age 16 years, but you may complete the series even if the recipient turns 17 before the series is completed.

Last reviewed: February 16, 2022

Yes. The second dose was given more than 4 days before the minimum interval of 6 calendar months, so it is considered invalid and should be repeated. The repeat dose should be administered the proper minimum interval (6 months) after the invalid dose. If this repeat dose is inadvertently given less than 6 months after the invalid dose, it does not need to be repeated again as long as the interval between the initial HepA vaccine and the most recent dose is at least 6 calendar months.

Last reviewed: June 25, 2023

You should use condoms until a postvaccination blood test (hepatitis B surface antibody, or anti-HBs) shows that your partner is protected from HBV infection. The efficacy of latex condoms in preventing infection with HBV is unknown, but their proper use might reduce the risk of transmission. Your sexual partner should have the 2- or 3-dose series of HepB vaccine (depending on brand) and postvaccination blood testing 1 to 2 months after the last dose of vaccine. If your partner’s test shows adequate anti-HBs (at least 10 mIU/mL), then they should be protected against HBV infection.

Last reviewed: July 21, 2023

No. Serologic testing for varicella should be considered only for pregnant people who do not have evidence of immunity (reliable history of chickenpox or documented vaccination). Once a person has been found to be seropositive, it is not necessary to test again in the future.

Last reviewed: May 16, 2023

Single antigen tetanus toxoid should only be used in rare instances, for example when a person has had a documented severe allergic response to diphtheria toxoid.

Last reviewed: March 31, 2022

Under the new recommendations, adults who have ever had at least one dose of PPSV23 do not need another dose of PPSV23 after turning 65. They have two options:

  • One dose of PCV20, or
  • One dose of PCV15
Last reviewed: April 5, 2024

FluMist Quadrivalent (LAIV4; AstraZeneca) is currently approved by FDA only for healthy non-pregnant people age 2 through 49 years.

Last reviewed: September 10, 2023

Since both Kinrix and Quadracel are licensed and recommended only for children ages 4 through 6 years, you should take measures to prevent this error in the future. However, you can count this as a valid dose for DTaP and IPV as long as you met the minimum interval between administering dose #3 and dose #4 of DTaP (6 months) and dose #2 and dose #3 of IPV (4 weeks).

Last reviewed: July 15, 2023

It is not recommended to remove the stopper from a vaccine vial before administering a vaccine to a person who has a severe life-threatening allergy to latex. The vaccine has already been exposed to the rubber stopper in the vial, which might be enough of an exposure to cause a reaction. These people should not be given the vaccine.

Last reviewed: August 29, 2022

No. Documented receipt of Shingrix cannot be used as proof of immunity to varicella. Additionally, a dose of Shingrix cannot be counted as a dose of varicella vaccine.

Last reviewed: March 9, 2022

ACIP recommends 2 doses of MMR given at least 4 weeks apart for any adult born in 1957 or later who plans to travel internationally. There is no harm in giving MMR vaccine to a person who may already be immune to one or more of the vaccine viruses.

Last reviewed: June 19, 2023

CDC states (www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#timing-spacing-interchangeability) that a person who moves to an older age group between vaccine doses should receive the vaccine product and dosage for the older age group for all subsequent doses.

Children who initiated their primary series with Pfizer-BioNTech brand products and turn age 5 years during the primary series have two options:

  1. Receive a single dose of updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine, 0.3 mL/10 mcg (blue cap; blue label) on or after turning age 5 years. If the 10-mcg dose is the second dose, administer 3–8 weeks after the first dose; if it is the third dose, administer at least 8 weeks after the second dose, OR
  2. Complete the 3-dose series with updated (2023–2024 Formula) Pfizer-BioNTech COVID-19 Vaccine for ages 6 months–4 years, 0.3 mL/3 mcg (yellow cap; yellow label), as outlined in the FDA EUA.
Last reviewed: March 19, 2024

Children who initiate the Moderna 2-dose vaccination series at age 4 years and turn 5 years-old before receiving the second dose should receive the second dose in the series (no dose change is needed). See www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#timing-spacing-interchangeability.

Last reviewed: March 19, 2024

No. Only the number of doses indicated in the manufacturer’s package insert should be withdrawn from the vial. For some vaccines, the package insert also may indicate the maximum recommended number of punctures of the vial stopper. After the maximum number of doses has been withdrawn or the number of punctures of the stopper has met the recommended limit, the vial should be discarded, even if there is vaccine remaining in the vial and the expiration date has not been reached. Never use partial doses from two or more vials to obtain a dose of vaccine.

Last reviewed: July 26, 2023

ACIP recommends booster doses of MenB vaccines for people at increased risk of MenB disease. Booster doses should be administered to people in the following groups as long as increased risk remains:

  • People with functional or anatomic asplenia, including sickle cell disease
  • People with persistent complement component deficiency (an immune system disorder)
  • People who take a complement inhibitor (examples include eculizumab [Soliris] or ravulizumab [Ultomiris])
  • Microbiologists who routinely work with meningococcal isolates
  • Previously vaccinated people who are at risk during a meningococcal B disease outbreak

Because protective antibody levels produced by the primary series begin to wane within 1–2 years, the first booster dose is recommended one year after completion of the primary series, with subsequent booster doses every 2–3 years as long as increased risk remains. Previously vaccinated people identified by public health as being at risk during a meningococcal B outbreak should receive a booster dose if it has been at least one year since completion of their primary series, though depending upon the specific circumstances, public health may recommend a booster dose as little as 6 months after completion of the primary series.

Last reviewed: March 24, 2024

The patient should be vaccinated at least 2 weeks before the splenectomy, if feasible. If not, vaccinate as soon as possible. Depending upon products available, he has two options:

  • One dose of PCV20 alone, or
  • One dose of PCV15 followed by a dose of PPSV23

CDC recommends that if using the PCV15 and PPSV23 series, a minimum interval of 8 weeks can be considered for adults with an immunocompromising condition (including splenectomy), cochlear implant, or cerebrospinal fluid leak.

Last reviewed: April 5, 2024

CDC states (www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#timing-spacing-interchangeability) that if a person moves to an older age group between vaccine doses, they should receive the vaccine product and dosage for the older age group for all subsequent doses. Thus, CDC’s general recommendation in this case is to complete the primary series with the dose appropriate for a child age 12 years.

In the case of immunocompromised children who initiate the primary series before turning 12 years old and need to complete the primary series after turning 12, the FDA EUA also permits completing the entire 3-dose series with the formula authorized for children ages 5 through 11 years.

Last reviewed: March 19, 2024

The safety and effectiveness of RSV vaccines have not been studied in infants. The family should be informed of the error, and nirsevimab should be administered as recommended as soon as feasible. CDC experts recommend that if you administer nirsevimab within 72 hours of the error, and you know where the RSV vaccine was injected, you should administer the nirsevimab in a different anatomic site. Facilities that stock RSV vaccine and nirsevimab should put systems and procedures in place to prevent this type of error, including staff training, clear labeling, and warnings in storage units. This medication error and any suspected adverse events following the error should be reported to the Vaccine Adverse Event Reporting System (VAERS) at https://vaers.hhs.gov.

For additional information about this type of error, see CDC’s COCA Now: Clinician Outreach Communication Activity update, dated January 22, 2024, at https://emergency.cdc.gov/newsletters/coca/2024/012224.html.

CDC has developed a job aid to help clinical staff reduce the risk of administration errors related to RSV vaccines and nirsevimab:
• Only Administer Nirsevimab (Beyfortus, Sanofi) to Young Children (www.cdc.gov/vaccines/vpd/rsv/downloads/rsv-error-prevention-children.pdf)

Last reviewed: February 5, 2024

No. Giving FluMist is not considered an aerosol-generating procedure.

Last reviewed: September 10, 2023

No. The recommendation for a 3-dose HPV schedule does not apply to people with asplenia and neither does it apply to children 9 through 14 years with asthma, chronic granulomatous disease, chronic liver disease, chronic renal disease, central nervous system, anatomic barrier defects (such as a cochlear implant), complement deficiency, diabetes, heart disease or sickle cell disease unless the person is receiving immunosuppressive therapy for the condition.

Last reviewed: March 2, 2024

Secondary cases of Hib disease (illness occurring within 60 days of contact with a patient) occur but are rare. Secondary attack rates are higher among household contacts younger than 48 months (2.1%), especially those younger than 12 months (6%) and younger than 24 months (3%). Data are conflicting on the risk for secondary illness among child care contacts, but it is thought to be lower than among household contacts. Rifampin is recommended for chemoprophylaxis because it achieves high concentrations in respiratory secretions and eradicates nasopharyngeal carriage in more than 95% of carriers.

Index patients who are treated with an antibiotic other than cefotaxime or ceftriaxone and are younger than 2 years of age should receive rifampin prior to hospital discharge. Because cefotaxime and ceftriaxone eradicate Hib colonization, prophylaxis is not needed for patients treated with either of these antibiotics.

Rifampin chemoprophylaxis is recommended for all household contacts in households with members younger than 4 years who are not fully vaccinated, households with a child younger than 12 months who has not completed the primary Hib series, or households with a contact who is an immunocompromised child regardless of that child’s vaccination status.

Rifampin chemoprophylaxis is recommended in child care settings when two or more cases of invasive Hib disease have occurred within 60 days and unimmunized or underimmunized children attend the facility. When prophylaxis is indicated, it should be prescribed for all attendees, regardless of age or vaccine status, and for child care providers. See the current AAP Red Book chapter on Haemophilus influenzae infections for more information on this issue.

There are no guidelines for control measures around cases of invasive nontype b H. influenzae disease. Chemoprophylaxis is not recommended for contacts of persons with invasive disease caused by nontype b H. influenzae because cases of secondary transmission of disease have not been documented.

Last reviewed: July 31, 2022

The parent/caregiver should be notified immediately, warned of the possible increased risk for hospitalization and severe dengue if the person develops a subsequent natural dengue infection, and the need to seek immediate medical attention if warning signs of severe dengue develop.

Clinic staff should review the incident and ensure that staff members responsible for vaccination have had sufficient training and protocols are in place to prevent such errors.

The use of tools, such as the CDC prevaccination checklist, helps prevent such errors: (www.cdc.gov/dengue/resources/DVBD_FS_Vaccination_Checklist-508.pdf).

Last reviewed: February 16, 2022

Tetanus toxoid became commercially available in 1938, but was not widely used until the military began routine vaccination in 1941. Routine administration of tetanus toxoid was recommended by the AAP in 1944. Most World War II military personnel received at least one dose of tetanus toxoid, but civilian use, particularly for adults, did not increase until after the war. You should not assume the tetanus vaccination status for any person based on their age alone. Only a written record is acceptable proof of immunization. People without documentation should be assumed to be unimmunized.

Last reviewed: March 31, 2022

In its 2006 ACIP recommendation for the prevention of hepatitis B, an accelerated 4-dose series of hepatitis B vaccine (which was not FDA-approved) was described as acceptable. CDC experts no longer recommend that approach when travel is imminent because other FDA-approved options exist.

The simplest option is Heplisav-B: its 2-dose series may be completed in 4 weeks. If Heplisav-B is unavailable, another option is to give the first 3 doses of the 4-dose accelerated schedule for Twinrix (HepA-HepB) at 0 days, 7 days, and 21-30 days and to have her return for a fourth dose 12 months after dose 1. Although this patient does not need the hepatitis A component, a combination vaccine such as Twinrix may be used if a single antigen option is not feasible; the additional doses of hepatitis A vaccine are not harmful.

Last reviewed: July 21, 2023

Contrary to the information provided in the vaccine package insert, which states that pregnancy should be avoided for 3 months, the ACIP recommends that a wait of 1 month is sufficient.

Last reviewed: May 16, 2023

In 2020, CDC published revised recommendations for hepatitis A postexposure prophylaxis (PEP). Please see the complete PEP recommendations at www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf, with special attention to Table 4 on page 19 and Appendix B: Provider Guidance on Risk Assessment for Hepatitis A Postexposure Prophylaxis, beginning on page 36.

Healthy people who have completed the HepA vaccination series at any time do not need additional PEP if they are exposed to HAV. People who have recently been exposed to HAV and who have not received HepA vaccine previously should receive PEP as soon as possible, within 2 weeks of exposure.

People age 12 months and older exposed to HAV within the past 14 days and who have not previously completed the HepA vaccine series should receive a single dose of HepA vaccine as soon as possible. In addition to vaccine, immune globulin (IG; 0.1 mL/kg) may be administered to people older than age 40 years depending on the providers’ risk assessment. For long-term immunity, the HepA vaccine series should be completed with a second dose at least 6 months after the first dose. However, the second dose is not necessary for PEP. A second dose should not be administered sooner than 6 calendar months after the first dose, regardless of HAV exposure risk.

People age 12 months or older who are immunocompromised or have chronic liver disease, and who have been exposed to HAV within the past 14 days and have not previously completed the HepA vaccination series, should receive both IG (0.1 mL/kg) and HepA vaccine at the same visit in a different anatomic site (for example, separate limbs) as soon as possible after exposure. For long-term immunity, the HepA vaccination series should be completed with a second dose at least 6 months after the first dose. However, the second dose is not necessary for PEP. A second dose should not be administered sooner than 6 calendar months after the first dose, regardless of HAV exposure risk.

People with HIV infection develop protective levels of antibody more slowly and are less likely to develop protective antibody levels after vaccination with HepA, especially if their CD4+ count is low at the time of vaccination. Protection following vaccination of a person with HIV may wane over time. Vaccine should be administered if the exposed individual is not fully vaccinated; however, CDC also advises clinicians to consider administering IG PEP to an individual with HIV after a high-risk exposure (such as a household or sexual contact) even if the individual has been fully vaccinated.

Twinrix contains half the amount of hepatitis A antigen as a standard single-dose adult HepA vaccine. Twinrix should not be used for PEP but may be used to confer protection to at-risk but not yet exposed persons during an outbreak.

Infants younger than age 12 months and persons for whom vaccine is contraindicated should receive IG (0.1 mL/kg) instead of HepA vaccine as soon as possible and within 2 weeks of exposure. MMR and varicella vaccines should not be administered sooner than 6 months after IG administration in order to avoid possible IG interference with the effectiveness of MMR and varicella vaccines.

Last reviewed: June 25, 2023

You can give rotavirus vaccine through a tube as long as the child is otherwise eligible.

Last reviewed: December 28, 2022

Kinrix (GSK) and Quadracel (Sanofi) brands of combination DTaP-IPV vaccine are licensed and recommended only for use in children ages 4 through 6 years, so you should take measures to prevent this error in the future. However, you can count the IPV dose as valid as long as it has met the minimum interval (4 weeks between doses except for the final dose in the series, which should be 6 months from the previous dose). With regard to the mistaken administration of the DTaP in a child older than age 6 years, the dose can be counted and does not need to be repeated with Td.

Last reviewed: July 15, 2023

Yes. Shingrix is not a live virus vaccine and does not interfere with the tuberculin skin test (TST): it may be administered any time before or after a TST. Administration of a live virus vaccine can interfere with a tuberculin skin test (TST). If the TST is not administered on the same day as a live virus vaccine, the TST should be delayed until 4–6 weeks after the vaccination.

Last reviewed: March 9, 2022

This page was updated on .

Our Affiliated Sites

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