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 (1372)

The Advisory Committee on Immunization Practice (ACIP) does not recommend zoster vaccination for immunocompetent people younger than age 50 years regardless of their history of shingles.

Last reviewed: March 9, 2022

Adults without evidence of immunity and no contraindications to MMR vaccine can be vaccinated without testing. Only adults without evidence of immunity might be considered for testing for measles-specific IgG antibody, but testing is not needed prior to vaccination.

CDC does not recommend measles antibody testing after MMR vaccination to verify the patient’s immune response to vaccination.

Two documented doses of MMR vaccine given on or after the first birthday and separated by at least 28 days is considered proof of measles immunity, according to ACIP. Documentation of appropriate vaccination supersedes the results of serologic testing for measles, mumps, rubella, and varicella.

Last reviewed: June 19, 2023

Yes, unless the person is allergic to any of the vaccine components. HepA vaccination is safe and effective and is recommended for any person who wishes to obtain immunity.

Last reviewed: June 25, 2023

CDC began adding barcodes to VISs in 2012. The barcode is intended to save time and prevent documentation errors by allowing immunization providers to scan the name and edition date of the VIS, information required to be documented in the permanent record of immunization, into an electronic medical record, immunization information system, or other electronic database. Scanning the barcode instead of manually recording the information is optional but can be helpful.

Using 2D barcodes requires a 2D barcode scanner and software that is programmed to accept and process data contained in the VIS barcodes. Providers may continue to use any VISs without barcodes as long as the VIS content is otherwise the same. For more information about using barcodes, visit www.cdc.gov/vaccines/hcp/about-vis/barcodes-faq.html.

Last reviewed: June 6, 2023

If administered vaccine is found to be stored at an inappropriate temperature, whether too cold or too warm, the provider should contact the state health department to determine whether the vaccine dose is invalid. If the vaccine dose is determined to be invalid, another dose should be given. This applies to both inactivated and live vaccines. If the damaged vaccine was a live virus vaccine (e.g., MMR, MMRV, VAR), you should wait at least 4 weeks after the previous (damaged) dose was given before repeating it. If the damaged vaccine was an inactivated vaccine, you can give the repeat dose on the same day you gave the damaged dose or at any other time, with one exception. The exception is Shingrix (herpes zoster vaccine), which should be repeated at least 28 days later due to the potential for increased side effects due to the chemical adjuvant it contains to enhance its effectiveness. If you prefer, you can perform serologic testing to check for immunity for certain vaccinations (e.g., measles, rubella, hepatitis A, diphtheria, varicella, and tetanus).

Last reviewed: July 26, 2023

Large pre-licensure clinical trials of both RotaTeq and Rotarix did not find an increased risk for intussusception among vaccine recipients. A large post-licensure study of more than 1.2 million rotavirus vaccine recipients found a very small increased risk of intussusception (1 to 1.5 additional cases of intussusception per 100,000 vaccinated infants) in the 7 to 21 days following the first dose. No increased risk of intussusception was found after the second or third doses. CDC and the Food and Drug Administration (FDA) continue to believe that the benefits of rotavirus vaccination outweigh the risks associated with vaccination and that routine vaccination of infants should continue.

A study conducted by the CDC Vaccine Safety Datalink (VSD) between May 2006 to February 2010 found no increased risk of intussusception following vaccination with RotaTeq. However, the study indicated an increased risk of intussusception following dose 1 and dose 2 of Rotarix. CDC estimates that there is a small increased risk of intussusception, usually within the first week after dose 1 or dose 2 of rotavirus vaccine, resulting in one additional case for every 20,000 to 100,000 U.S. infants who receive the vaccine.

Last reviewed: June 7, 2023

The third dose of Vaxelis vaccine administered at age 5 months (less than 24 weeks of age) is not considered a valid dose of the HepB component, because the last dose of HepB vaccine should be given at 24 weeks of age or older. The child will need an additional dose of HepB vaccine at age 24 weeks or older, and at least 4 weeks after the inadvertent dose of Vaxelis. The DTaP and IPV components of the Vaxelis dose erroneously administered at age 5 months are considered valid doses and do not need to be repeated, as long as there was a minimum 4-week interval between the second and third doses of either component.

Last reviewed: July 31, 2022

In 2008, FDA licensed Kinrix, a combination DTaP and IPV vaccine. It is approved for use as the fifth dose of DTaP and the fourth dose of IPV in children ages 4 through 6 years who received DTaP (Infanrix) and/or DTaP-HepB-IPV (Pediarix) as the first three doses and DTaP (Infanrix) as the fourth dose. It should not be given to children younger than age 4 years.

Last reviewed: July 15, 2023

Latex is a product of the rubber tree. It is processed and used in various products, including some that come in contact with vaccines. Latex may be present in syringe plungers, vial stoppers, or in the tip caps on prefilled syringes. Some people develop sensitivity to latex, particularly if they have had significant cumulative latex exposure, such as from repeated surgeries early in life or employment in the healthcare industry.

The most common type of latex sensitivity is contact-type allergy; however, on rare occasions, severe (anaphylactic) allergy occurs. People with a history of anaphylactic reactions to latex should generally not be given vaccines that have been in contact with natural rubber or latex, either in the vial or in the syringe, unless the benefit of vaccination outweighs the risk of a potential allergic reaction. People with latex allergies that are not anaphylactic in nature may be vaccinated as usual.

Last reviewed: August 29, 2022

Yes. In this situation, a second dose of Tdap should be administered at the recommended age of 11 or 12 years.

Last reviewed: March 31, 2022

What you do depends on when the error is identified. If the error is discovered while the person is still in the office, you can administer the other “half” of the Engerix-B dose. If the error is discovered later, the dose should not be counted. The person should be recalled to the office and given a full age-appropriate 1.0 mL repeat dose. The same recommendation would apply if the error was with Recombivax HB.

Last reviewed: January 17, 2025

ACIP does not specifically recommend eye protection when administering vaccines to prevent exposure to blood spatter.

In 2020, in response to the COVID-19 pandemic, CDC temporarily recommended the use of protective eyewear in areas where SARS-CoV-2 was circulating widely to reduce the risk of infection with SARS-CoV-2. In the setting of widely available and effective COVID-19 vaccines and treatments, CDC resumed recommending standard pre-pandemic infection control practices during vaccination.

Last reviewed: December 28, 2022

Yes. Vaccinated women still need to see their healthcare provider for periodic cervical cancer screening. The vaccine does not provide protection against all types of HPV that cause cervical cancer, so even vaccinated women will still be at a small risk for some cancers from HPV.

Last reviewed: March 2, 2024

Giving patients an influenza Vaccine Information Statement (VIS) is mandatory under the National Childhood Vaccine Injury Act of 1986. The VIS must be given to all adults as well as to parents or guardians of children prior to vaccination. Two VISs are available, one for live attenuated influenza vaccine (LAIV) and one for inactivated influenza vaccine (IIV) and recombinant vaccine (RIV). The IIV and RIV VIS and all of its translations are available here: www.immunize.org/vaccines/vis/influenza-inactivated/. The LAIV VIS and all of its translations are available here: www.immunize.org/vaccines/vis/influenza-live/. Current influenza vaccine VISs are dated August 6, 2021.

Immunize.org also offers a printable PDF document with QR codes for easy access to all of the IIV and RIV influenza vaccine VIS translations: www.immunize.org/wp-content/uploads/catg.d/p2092.pdf. Healthcare providers or recipients can scan the codes to access a digital copy of the translation on their mobile device.

Last reviewed: August 11, 2024

Yes. VFC-eligible pregnant adolescents younger than age 19 may receive VFC-funded Abrysvo (Pfizer) RSV vaccine during pregnancy, if indicated, in VFC-participating facilities. Contact your state or territorial immunization program with questions about VFC and Abrysvo.

Last reviewed: August 25, 2024

ACIP has made a series of changes in its recommendations for pneumococcal vaccination of adults since 2022 in response to the licensure of new pneumococcal conjugate vaccines (PCVs). In January 2022, CDC published recommendations for PCV15 (Vaxneuvance, Merck) and PCV20 (Prevnar 20, Pfizer) as pneumococcal vaccination options for all adults age 65 and older and for adults age 19 through 64 with certain medical conditions or other risk factors for pneumococcal disease. ACIP stopped recommending PCV13 (Prevnar 13, Pfizer) for adults; however, CDC clinical guidance allows for its use in rare circumstances if only PCV13 is accessible and the patient would otherwise be unvaccinated. When PCV15 is used routinely, it should be used in series with 23-valent pneumococcal polysaccharide vaccine (PPSV23, Pneumovax, Merck) given one year later. 

In June 2024, ACIP recommended PCV21 (Capvaxive, Merck) as an option in all situations where PCV is recommended for adults. As with PCV20, PPSV23 is not recommended following PCV21. 

In October 2024, ACIP recommended that routine immunization of all adults with a PCV begin at age 50 years, rather than age 65 years. This change was made to address the substantial amount of preventable invasive pneumococcal disease (IPD) among adults age 50 through 64.   

Adults 19 through 49 years eligible for pneumococcal vaccination as a result of a high-risk condition who have no or unknown history of PCV should receive one dose of PCV20 or PCV21 alone, or a dose of PCV15 followed by a dose of PPSV23 one year later (with a minimum interval option of 8 weeks for people with an immunocompromising condition, cochlear implant, or cerebrospinal fluid leak).  

The current CDC guidance for the use of pneumococcal vaccines in adults are outlined in this job aid from CDC: www.cdc.gov/pneumococcal/downloads/Vaccine-Timing-Adults-JobAid.pdf.  

Immunize.org has standing orders for pneumococcal vaccination of adults for all PCV options and PPSV23 (if indicated) at:  www.immunize.org/catg.d/p3075.pdf. 

Last reviewed: November 13, 2024

ACIP recommends meningococcal vaccination only for high-risk children younger than 11 years. ACIP defines high-risk children age 2 months and older as (1) those 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) those with functional or anatomic asplenia, (3) those with HIV infection, (4) those traveling to or residing in an area of the world where meningococcal disease is hyperendemic or epidemic or (5) those identified by public health officials as being at risk during a community outbreak attributable to a vaccine serogroup.

Menveo (MenACWY-CRM), in its two-vial formulation requiring reconstitution, is approved for children age 2 months and older; the one-vial formulation that does not require reconstitution may be administered to children age 10 years or older. MenQuadfi (MenACWY-TT) is approved for children age 2 years and older. Children at increased risk for meningococcal disease should receive booster doses as long as they remain at increased risk.

Last reviewed: November 15, 2024

All children age 6 months and older should be vaccinated against COVID-19 with at least one dose of the current 2024–2025 formulation mRNA vaccine. COVID-19 vaccination of children in this age group has been demonstrated to be safe and to prevent hospitalization and severe complications of COVID-19 illness. Both Pfizer-BioNTech and Moderna mRNA products are authorized for use in children down to 6 months of age. Novavax adjuvanted protein subunit vaccine is authorized for use beginning at age 12 years.

Children age 6 months through 4 years initially require a primary series of two (Moderna) or three (Pfizer-BioNTech) doses of the same brand. The primary series may include doses of previously authorized formulations. CDC recommends use of the same brand for all recommended doses given to children younger than age 5 years. If it is not possible to do so because the brand is unavailable at the vaccination visit, the brand of a previous dose is unknown, or because the child would not or should not be vaccinated with the previous brand for any reason, then administer the age-appropriate formulation of the available brand. A 3-dose primary series is required for children age 6 months through 4 years who have a mixed-brand primary series. A 3-dose primary series is also required for all children and adults who have moderate or severe immunocompromise. 

Last reviewed: November 16, 2024

Use of either brand of MenB in persons younger than age 10 years is off-label in the U.S. There is no ACIP recommendation for use of this vaccine for this age group.

Bexsero (MenB-4C) has been studied among infants and is approved for infants by the European Medicines Agency (the European version of the U.S. Food and Drug Administration). It is routinely recommended for infants in the United Kingdom (see www.nhs.uk/vaccinations/menb-vaccine/ for details). A clinician may choose to use a vaccine off-label if, in their opinion, the benefit of the vaccine exceeds the risk from the vaccine.

Last reviewed: November 15, 2024

No, the dose should not be repeated. The Clinical Implications of Nonstandard Vaccination Practices subsection of the Vaccine Administration section of CDC’s General Best Practices for Immunization explains that the immune response to vaccines recommended to be administered by the subcutaneous route is unlikely to be affected if the vaccines are inadvertently administered by the intramuscular route. For this reason, repeating doses of vaccine administered by the intramuscular route when recommended by the subcutaneous route is not necessary. See this subsection here: www.cdc.gov/vaccines/hcp/imz-best-practices/vaccine-administration.html#cdc_report_pub_study_section_6-clinical-implications-of-nonstandard-vaccination-practices.

Last reviewed: January 17, 2025

Lowering the age for routine PCV use in adults from 65 to 50 years was intended to address the substantial burden of preventable invasive pneumococcal disease (IPD) and pneumococcal pneumonia in people age 50 through 64 years. Despite long-standing risk-based recommendations for pneumococcal vaccination of adults age 19 through 64 at increased risk of IPD, by 2022, just 23% of this target group had received at least one adult pneumococcal vaccination, according to CDC’s National Health Interview Survey. In addition, according to CDC surveillance data, by age 50, the rate of IPD among Black adults is higher than the rate in the general population of the United States by age 65. Finally, the newer PCV products protect against a substantially larger proportion of pneumococcal serotypes responsible for IPD in adults, compared to PCV13. ACIP members expressed their hope that expanding the simple age-based recommendation to give PCV at age 50 would increase access to and administration of PCV, especially among unvaccinated people at increased risk of IPD. 

Last reviewed: November 13, 2024

It is likely. Effectiveness of pneumococcal polysaccharide vaccine (PPSV23) begins waning significantly after about 5 years. While current pneumococcal conjugate vaccines (PCVs) are expected to remain effective longer than that, for at least several years, a future PCV dose may be needed by those vaccinated at younger ages to boost protection later in life. When ACIP voted to lower the routine PCV vaccination age to 50, the committee took into consideration that an additional dose, perhaps 10 or 15 (or more) years later, may be needed. In coming years, ACIP will periodically review any evidence of waning protection, evaluate future pneumococcal vaccine products, and make recommendations for revaccination of older adults when needed.

Last reviewed: November 13, 2024

Quadracel (Sanofi) is a combination DTaP and IPV vaccine. It was approved by the FDA in 2015 for use in children 4 through 6 years of age as the fifth dose in the DTaP series, and as the fourth or fifth dose in the IPV series in children who have received 4 doses of Pentacel (DTaP-IPV-Hib, Sanofi) and/or Daptacel (DTaP, Sanofi) vaccine. It should not be given to children younger than age 4 years. CDC published a short MMWR article about Quadracel on September 4, 2015 (www.cdc.gov/mmwr/pdf/wk/mm6434.pdf, pages 948–9).

Last reviewed: July 15, 2023

Even with appropriate equipment and temperature monitoring practices in place, power disruption can result in destruction of the entire vaccine supply. Precautions should always be taken to protect the storage unit’s power supply. CDC recommends the following best practices.

  • Plug in only one storage unit per electrical outlet to avoid creating a fire hazard or triggering a safety switch that turns the power off.
  • Use a safety-lock plug or an outlet cover to prevent the unit from being unplugged.
  • Post “DO NOT UNPLUG” warning signs at outlets and on storage units to alert staff, custodians, electricians, and other workers not to unplug units. A sign is available from Immunize.org at www.immunize.org/catg.d/p2090.pdf.
  • Label fuses and circuit breakers to alert people not to turn off power to a storage unit. A label is available from Immunize.org at www.immunize.org/catg.d/p2091.pdf.
  • Use caution when using power outlets that can be tripped or switched off and avoid using:
    • Built-in circuit switches (may have reset buttons)
    • Outlets that can be activated by a wall switch
    • Multi-outlet power strips.

Include this information as well as what to do if a vaccine storage temperature excursion occurs in your facility’s emergency Standing Operating Procedures.

Last reviewed: July 26, 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

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

CDC publishes VISs in English only; all translations have been developed by others. To access all currently available VISs in dozens of languages, go to Immunize.org’s website at www.immunize.org/vis.

Last reviewed: June 6, 2023

Not all stoppers in vaccine vials contain latex. Some manufacturers have switched to synthetic rubber-like materials that do not contain rubber latex or dry natural rubber. The best approach is to check the package insert, which will indicate if the packaging contains latex. Also, remember that prefilled syringes could contain natural rubber in the plunger, in the needle cover, or in the tip cap. This information is also supplied in the package insert.

Last reviewed: August 29, 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: January 17, 2025

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: August 11, 2024

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. 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

Any temperature reading outside the recommended range for vaccine storage is a temperature excursion. However, it is generally the total amount of time, or cumulative time, out of range that affects the viability of vaccine. Any time appropriate vaccine storage temperatures are in question, stop giving vaccinations and contact your state immunization program and/or the vaccine manufacturer for further guidance about whether or not a vaccine may be used. The CDC Storage and Handling Toolkit contains detailed guidance on the management of a temperature excursion. See www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf, pages 12–15. Additional information for COVID-19 and mpox vaccine temperature excursions is available in the addendum at the end of the toolkit.

Last reviewed: July 26, 2023

Yes. HPV vaccine is recommended for all people through age 26 years, regardless of sexual orientation or gender identity.

Last reviewed: March 2, 2024

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

All people age 19 through 49 with the following medical conditions who have no history of pneumococcal vaccination or an unknown pneumococcal vaccination history should receive either a single dose of PCV20 or PCV21 alone or a dose of PCV15 followed by a dose of PPSV23 at least 1 year later. If using the PCV15 + PPSV23 series, clinicians can consider giving the dose of PPSV23 a minimum of 8 weeks later for more rapid protection against the serotypes unique to PPSV23 to people with immunocompromising condition, cochlear implant, or cerebrospinal fluid (CSF) leak. The conditions are:

  • Alcoholism or cigarette smoking
  • CSF leak
  • Chronic heart disease, including congestive heart failure and cardiomyopathies, excluding hypertension
  • Chronic liver disease
  • Chronic lung disease, including chronic obstructive pulmonary disease, emphysema, and asthma
  • Cochlear implant (including those preparing for cochlear implant)
  • Diabetes mellitus
  • Decreased immune function from disease or drugs (immunocompromising conditions), including:
    • Chronic renal failure or nephrotic syndrome
    • Congenital or acquired 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)
    • Diseases or conditions treated with immunosuppressive drugs or radiation therapy, including Hodgkin disease, leukemias, lymphomas, malignant neoplasms, and solid organ transplant
    • HIV infection

For details of vaccination following hematopoietic stem cell transplantation, see www.cdc.gov/vaccines/hcp/imz-best-practices/altered-immunocompetence.html

Public health authorities working with Alaska Natives and American Indians may provide additional guidance for individuals in those communities where the overall risk of invasive pneumococcal disease is increased.

Last reviewed: November 13, 2024

ACIP recommends that microbiologists who work with meningococcal isolates in a laboratory receive both MenB and MenACWY vaccines. MenB can be given at the same time as any other vaccine. For accelerated protection, you can administer a 3-dose series of Bexsero (MenB-4C) or Trumenba (MenB-FHbp) on a 0-, 1–2-, and 6-month schedule. If dose 2 is delayed and administered 6 months or longer after dose 1, the primary series is complete.

Because protective antibody levels begin to wane within 1–2 years after completing the primary series, ACIP recommends a booster dose of MenB one year after completing the primary series, followed by a booster dose every 2–3 years thereafter, as long as risk remains. MenB vaccine brands work differently and are not interchangeable. All doses, including booster doses, should be of the same type (either MenB-FHbp or MenB-4C). If the primary series type is not known or is not available, restart the primary series with the available brand.

Microbiologists may receive a dose of MenABCWY (Penbraya, Pfizer) as an alternative to separate administration of MenACWY and MenB (MenB-FHbp, Trumenba) when both vaccines would be given on the same clinic day and at least 6 months have elapsed since most recent Penbraya dose.

Last reviewed: November 15, 2024

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: January 17, 2025

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

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: August 11, 2024

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

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

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: January 17, 2025

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

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

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: November 15, 2024

All three RSV vaccines (Arexvy, Abrysvo, mResvia) are administered by the intramuscular route.

Last reviewed: August 25, 2024

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 2024–2025 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: November 16, 2024

For adults 50 years and older with no prior pneumococcal vaccination or whose previous vaccination history is unknown, you have two options: 

  • One dose of PCV20 or PCV21 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: November 13, 2024

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 for meningococcal B disease, such as this patient, may receive MenB vaccination. ACIP does not specify use of the 3-dose schedule for immunocompromised people who are not at increased risk for meningococcal B disease. 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: November 15, 2024


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Last reviewed: November 13, 2024

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

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

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

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