Ask the Experts: All Questions

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Results (1361)

PCV vaccines and PPSV23 should not be administered at the same visit or at an interval less than 8 weeks.

In children through age 18 years, if PCV and PPSV23 are administered at the same visit, the PCV dose should be repeated, and should be administered no earlier than 8 weeks after doses that were administered on the same day. However, in adults age 19 years or older, if a PCV and PPSV23 are administered at the same visit or at an interval less than 8 weeks, CDC recommends that neither dose be repeated.

Last reviewed: November 13, 2024

Yes, you can. Some, but not all, studies have reported increased rates of febrile seizures among children, especially those age 12 through 23 months, who received simultaneous vaccination with IIV and pneumococcal conjugate vaccine (PCV13, Pfizer) or DTaP vaccine (Daptacel, Infanrix, Pediarix, Pentacel), when compared with children who received these vaccines separately. However, because of the risks associated with delaying either of these vaccines, ACIP does not recommend administering them at separate visits or deviating from the recommended vaccine schedule in any way. The risk of febrile seizure following coadministration of influenza vaccine with the newer PCV15 or PCV20 pneumococcal conjugate vaccines has not been evaluated.

Febrile seizures may be triggered by any cause of fever and occur in up to 5% of all children They are generally benign. Healthcare providers should be prepared to answer parents’ questions about febrile seizures and fever when discussing vaccinations. Here is a CDC resource that addresses these concerns: www.cdc.gov/vaccine-safety/about/febrile-seizures.html.

Last reviewed: August 11, 2024

In general, although it is not ideal, receiving extra doses of vaccine poses no medical problem. However, receiving excessive doses of tetanus toxoid (e.g., DTaP, DT, Tdap, or Td) can increase the risk of a local adverse reaction. For details see the Extra Doses of Vaccine Antigens section of the ACIP “General Best Practice Guidelines for Immunization” at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html.

Vaccination providers frequently encounter people who do not have adequate documentation of vaccinations. Providers should only accept written, dated records as evidence of vaccination. With the exception of influenza vaccine and pneumococcal polysaccharide vaccine, self-reported doses of vaccine without written documentation should not be accepted. An attempt to locate missing records should be made whenever possible by contacting previous healthcare providers, reviewing state or local immunization information systems, and searching for a personally held record.

If records cannot be located or will definitely not be available anywhere because of the patient’s circumstances, children without adequate documentation should be considered susceptible and should receive age-appropriate vaccination. Serologic testing for immunity is an alternative to vaccination for certain antigens (e.g., measles, rubella, hepatitis A, diphtheria, and tetanus).

Last reviewed: June 19, 2023

The probability of a serious allergic reaction following any vaccine is extremely low if the person is properly screened. ACIP has not issued a recommendation that desensitization injections and vaccines be separated by any specific time period; consequently, we feel that you should take the opportunity to vaccinate.

Last reviewed: August 11, 2024

Yes. HepA vaccine should be given to all susceptible patients with chronic liver disease. HepA vaccine is very immunogenic.

Last reviewed: June 25, 2023

No. Twinrix contains 50% less hepatitis A antigen component than Havrix, GSK’s monovalent HepA [720 vs. 1440 El. U.], so the patient would not receive the recommended dose of HepA antigen.

Last reviewed: July 21, 2023

Even though the interval was shorter than the recommended one year, the dose of PPSV23 should be counted and does not need to be repeated. ACIP recommends that the routinely recommended interval between PCV15 and PPSV23 is 1 year, and the minimum interval is 8 weeks.

Last reviewed: November 13, 2024

Minimum intervals for Twinrix are 4 weeks between dose #1 and dose #2, and 5 months between dose #2 and dose #3.

Last reviewed: July 21, 2023

It seems tempting to wait for screening test results, but since this is a 2- or 3-dose series that most adults need, we do not recommend missing an opportunity to vaccinate. Vaccination today helps protect a person who needs it. Even for specialists who work with patient groups with an increased likelihood of previous infection, such as people who use injection drugs, we encourage administering the first dose just after screening (at the same visit). If results show no further vaccination is needed then the vaccine series can be stopped at that point. If the results show further vaccination is needed, as it will with most people, then only one or two more doses will be needed to complete the series.

Last reviewed: July 21, 2023


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Last reviewed: December 7, 2023

Because HepB vaccination is a series of 2 or 3 doses of vaccine, and because most older adults need vaccination, we recommend initiating the series whenever and in whatever setting the opportunity arises. There’s no downside to vaccinating, but delaying vaccination could leave someone vulnerable to infection. Patients who are vaccinated should be informed of the recommendation for a one-time triple panel screening test in the future.

Last reviewed: July 21, 2023

All hepatitis A-containing vaccine should be stored at refrigerator temperature at 2°C to 8°C (36°F to 46°F). The vaccine must not be frozen. Any vaccine exposed to freezing temperature should not be used. Do not use these or any other vaccines after the expiration date shown on the packaging. Any vaccine administered after its expiration date is not valid and should be repeated.

Last reviewed: June 25, 2023

Yes. A history of GBS unrelated to influenza vaccine is not a contraindication or precaution to influenza vaccination. GBS within 6 weeks following a previous dose of influenza vaccine is considered a precaution for use of influenza vaccines.

Last reviewed: August 11, 2024

As with all vaccines, a severe allergic reaction (e.g., anaphylaxis) to a vaccine component or to a prior dose is a contraindication to further doses of that vaccine. A history of encephalopathy within 7 days of receiving a previous pertussis-containing vaccine that is not due to another identifiable cause is a contraindication to both DTaP and Tdap.

Last reviewed: March 31, 2022

Draw the blood for screening first. It is possible to detect HBsAg from the HepB vaccine in serologic tests up to 18 days after vaccination, so CDC recommends obtaining blood for the screening triple panel before administering the first dose of vaccine to avoid any chance of a false positive HBsAg result. If the triple panel screening test needs to be done later, wait one month after administration of the most recent dose of HepB vaccine.

Last reviewed: July 21, 2023

According to CDC, MIS-C and MIS-A both include a dysregulated immune response to SARS-CoV-2 infection. Experts consider the benefits of vaccination to outweigh the theoretical risk of an MIS-like illness or the risk of myocarditis following COVID-19 vaccination in a person with a history of MIS-C or MIS-A if the person meets the following criteria: (1) they have clinically recovered, including return to baseline cardiac function; and (2) it has been at least 90 days since the diagnosis of MIS-C or MIS-A.

There are additional considerations for vaccination of those who do not meet these criteria. Refer to CDC’s detailed guidance for the most current clinical considerations for vaccination of children and adults who have experienced this syndrome following SARS-CoV-2 infection or who have experienced MIS-like illness following COVID-19 vaccination: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#covid19-vaccination-misc-misa.

Last reviewed: November 16, 2024

The amount of time in which a dose of vaccine must be used after reconstitution varies by vaccine and is usually outlined in the vaccine’s package insert. MMR must be used within 8 hours of reconstitution. MMRV must be used within 30 minutes; other vaccines must be used immediately. Immunize.org has a staff education piece that outlines the time allowed between reconstitution and use, as stated in the package inserts for a number of vaccines. This handout can be found at the following link: www.immunize.org/catg.d/p3040.pdf.

Last reviewed: July 26, 2023

What to do when doses of PCV15 and PPSV23 are given earlier than the recommended minimum interval of 8 weeks is not described in the ACIP pneumococcal recommendations. The CDC subject matter experts have provided the following guidance: in such a case, the dose given second does NOT need to be repeated. This is an exception to the usual procedure for a minimum interval violation (as described in CDC’s “General Best Practices Guidelines for Immunization”. The recommended interval between the dose of PCV15 and PPSV23 is one year and the recommended minimum interval between doses is 8 weeks.

Last reviewed: November 13, 2024

CDC’s General Best Practice Guidelines for Immunization states that, in general, you should only accept written records as proof of vaccination. If the person’s recollection is wrong, and the person is susceptible, then not vaccinating leaves them at ongoing risk.

If you have no record of HepB vaccination and you intend to do the triple panel screen, it is reasonable to proceed with giving the first dose of HepB vaccine after drawing blood for screening. If that triple panel screening test shows evidence that further vaccination is not needed, or if the patient locates records later, then discontinue vaccination at that point. If screening is not done, and records are unavailable, complete the series. If you screen the patient after a partial HepB vaccination series, the screening results might show a positive anti-HBs antibody; however, you should complete the vaccine series to ensure the patient develops the intended long-term protection from infection.

Last reviewed: July 21, 2023


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Last reviewed: December 7, 2023

The triple panel is important for vaccinated adults to find out if they have evidence of current or past infection, which could have occurred before vaccination. Antiviral treatment may be needed in certain situations.

Last reviewed: July 21, 2023

For most people the answer is NO. A negative anti-HBs result is a common finding when tested years after completing vaccination, and most healthy people may be reassured that they would still be protected from illness, if exposed.

Antibody titers naturally drift lower over the years; however, studies have shown that the majority of people who were effectively immunized decades earlier can mount an effective antibody response and prevent symptomatic or chronic infection after exposure. A study of members of the Alaskan Native population published in 2022 estimated that 86% had effective protection 35 years following vaccination. Even those few with serologic evidence of hepatitis B infection at some point after vaccination showed no evidence of active infection, which is the most important health outcome.

Revaccination is indicated for certain people at ongoing high risk, as specified in the 2018 ACIP recommendation (e.g., nonresponder infants born to people who tested positive for HBsAg, health care providers at risk of occupational exposure, and people on hemodialysis or with significant immunocompromise). For further details, see the 2018 ACIP recommendation, pages 23 and 24: www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6701-H.pdf.

Last reviewed: July 21, 2023

There are 4 different HepB vaccines approved for adults, plus the Twinrix (GSK) combination HepA-HepB vaccine. While all of the HepB vaccines licensed for adults are acceptable and recommended, with no preference among them expressed by ACIP, some of the differences among them are outlined below. Clinicians choosing among products may find it useful to consider these differences when making choices for their patient population.

The schedule for Heplisav-B (Dynavax) is 2 doses, given at least one month apart, while all other products require a 3-dose series given over a period of 6 months. Twinrix protects adults against both hepatitis A and B in 3 doses given over 6 months, if vaccination against both is desired. Heplisav-B and PreHevbrio (VBI), both show higher seroconversion rates among some groups that traditionally respond poorly to HepB; the immune response to Engerix-B (GSK) and Recombivax-HB (Merck) declines gradually after age 40, and may be lower in people who are obese or who have diabetes. PreHevbrio is the only HepB product that does not contain yeast, making it is safe for yeast-allergic recipients.

Recombivax-HB and Engerix-B are both recommended when vaccinating during pregnancy; neither Heplisav-B nor PreHevbrio are recommended during pregnancy at this time due to insufficient data available on the safety of these products when given during pregnancy. (Note: testing for pregnancy before HepB vaccination is not recommended.)

 

Last reviewed: July 21, 2023


2:53

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Last reviewed: December 7, 2023

If the vaccine type is unknown, but you have documentation, simply pick up the series where you left off and give dose 2 now—you never have to restart the vaccine series. The patient will need a total of three doses since the only 2-dose series option is for Heplisav-B. If you use Heplisav-B, complete the vaccination series by giving a dose now and a second Heplisav-B dose at least 4 weeks later. If you use any other HepB vaccine product, use a minimum interval of 8 weeks between dose 2 and dose 3 to complete the series. See the CDC’s recommended immunization schedule for details, available at www.cdc.gov/vaccines/hcp/imz-schedules/adult-age.html.

Last reviewed: July 21, 2023

In general, this is not an issue, but CDC recommends waiting at least 1 month (4 weeks) after HepB vaccination before drawing blood for the triple panel screen for hepatitis B. HBsAg present in the HepB vaccine has been detected in serologic tests up to 18 days after vaccine administration. You do not have to delay the triple panel screen until after the vaccine series is complete, as long as it’s been at least 4 weeks since the most recent dose.

If you screen the patient after a partial HepB vaccination series, the screening results might show a positive anti-HBs antibody; however, you will still need to complete the vaccine series to ensure the patient develops long-term protection from infection.

Last reviewed: July 21, 2023

MMRII (Merck) brand of MMR vaccine may be stored either in the refrigerator at 2°C to 8°C (36°F to 46°F) or in the freezer at -50°C to -15°C (-58°F to +5°F). Prescribing information for the Priorix (GSK) brand of MMR vaccine states that it should be stored refrigerated (at 2°C to 8°C), but not in the freezer. For both brands, the diluent should not be frozen and can be stored in the refrigerator or at room temperature.

If the MMR is combined with varicella vaccine as MMRV (ProQuad, Merck), it must be stored in the freezer at -50°C to -15°C (-58°F to +5°F).

Last reviewed: June 19, 2023

Precautions to these vaccines include:

  • A history of Guillain-Barré syndrome (GBS) within 6 weeks of receiving a tetanus toxoid-containing vaccine
  • A history of Arthus-type hypersensitivity reaction after receiving a previous tetanus or diphtheria toxoid-containing vaccine (defer vaccination until at least 10 years have elapsed since the last tetanus toxoid-containing vaccine)
  • A moderate or severe acute illness with or without fever
  • For pertussis-containing vaccines (DTaP and Tdap only): an additional precaution is a progressive or unstable neurologic disorder, including infantile spasms, uncontrolled seizures or progressive encephalopathy. DTaP and Tdap should be deferred until the neurologic status of the patient is clarified and stabilized.
Last reviewed: March 31, 2022

CDC guidance is that people who have a history of completely resolved myocarditis or pericarditis unrelated to COVID-19 vaccination (e.g., due to SARS-CoV-2 or other viruses) may receive any age-appropriate COVID-19 vaccine that is FDA-approved or FDA-authorized. “Complete resolution” includes resolution of symptoms attributed to myocarditis or pericarditis, as well as no evidence of ongoing heart inflammation or sequelae as determined by the person’s clinical team.

For people who have a history of myocarditis associated with MIS-C or MIS-A following SARS-CoV-2 infection, see CDC’s interim clinical considerations concerning COVID-19 vaccination and MIS-C and MIS-A: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#covid19-vaccination-misc-misa.

Complete and current clinical considerations for COVID-19 vaccination of patients with a history of myocarditis are available from CDC here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#myocarditis-pericarditis.

For additional information about myocarditis and mRNA COVID-19 vaccines, visit www.cdc.gov/vaccines/covid-19/clinical-considerations/myocarditis.html.

Last reviewed: November 16, 2024

There a several potential interpretations of an isolated anti-HBc positive result (with a negative HBsAg and negative anti-HBs). Additional evaluation of the patient’s immune status and risk history is needed. A 2011–2018 national survey found the prevalence of isolated positive anti-HBc is about 0.8%. The total anti-HBc tests are very accurate, at about 99.8% specificity; however, if a person has no risk factors for hepatitis B, the result may be a false positive. Other possibilities include: a past resolved infection; an occult infection (HBV DNA is detectable but surface antigen is not detected); an early infection tested during the brief period of time before anti-HBs antibodies are detectable; or, an infection with a hepatitis B virus with a mutant surface antigen not detectable by standard tests. Depending upon the circumstances, consultation with a specialist may be helpful.

Additional resources for the evaluation of isolated anti-HBc antibody results are available from the University of Washington: www.hepatitisb.uw.edu/go/screening-diagnosis/diagnosis-hbv/ core-concept/all and from CDC: www.cdc.gov/hepatitis-b/hcp/diagnosis-testing/#cdc_hcp_diagnosis_interpreting-how-to-interpret-test-results.

Last reviewed: July 21, 2023

When PCV15 is given to a healthy adult 65 years or older, PCV15 should be given first followed by PPSV23 one year later.

What to do when doses of PPSV23 and PCV15 are given before the recommended interval is not addressed in the ACIP recommendations. The CDC subject matter experts have advised that in such a case, the dose given second does NOT need to be repeated. This is an exception to the usual procedure for a minimum interval violation as described in CDC’s “General Best Practices Guidelines for Immunization” (see www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html).

Last reviewed: November 13, 2024

Both the inactivated (IIV) and recombinant (RIV) influenza vaccine VIS and the live influenza vaccine VIS were updated on August 6, 2021.

The IIV and RIV influenza vaccine VIS and all available translations of it are here: www.immunize.org/vaccines/vis/influenza-inactivated/. The live attenuated influenza (LAIV) VIS and all available translations of it are here: www.immunize.org/vaccines/vis/influenza-live/.

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

Last reviewed: August 11, 2024

Documentation is very important to the success of the adult HepB catch-up vaccination program. First, give the patient a personal record: let them know that taking a digital photo of their record is wise. Second, all states have an immunization information system, known as an IIS or immunization registry. Check the IIS for the patient’s vaccination records and report doses administered to the IIS to ensure a permanent record of vaccination exists that is accessible to other healthcare providers who need the information. This is the best way to minimize unnecessary repeated hepatitis B evaluation and vaccination in the future.

Last reviewed: July 21, 2023


1:40

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Last reviewed: December 7, 2023

Development of myocarditis or pericarditis within 3 weeks after a dose of any COVID-19 vaccine is a precaution to a subsequent dose of any COVID-19 vaccine, and subsequent doses should generally be avoided. Under certain conditions, the clinical team may determine that benefits of vaccination outweigh risks. See CDC’s detailed guidance for additional information about these clinical considerations: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#myocarditis-pericarditis.

Last reviewed: November 16, 2024

Unfortunately, serious errors in vaccine storage and handling like this occur too often. If you suspect that vaccine has been mishandled, you should store the vaccine as recommended, then contact the manufacturer or state/local health department for guidance on its use. This is particularly important for live virus vaccines like MMR and varicella.

Last reviewed: June 19, 2023

Yes. Mothers who have never received Tdap and who did not receive it during pregnancy should receive it immediately postpartum or as soon as possible thereafter. Breastfeeding does not decrease the immune response to routine childhood vaccines and is not a contraindication for any vaccine except smallpox. Breastfeeding is a precaution for yellow fever vaccine and the vaccine can be given for travel when indicated.

Last reviewed: March 31, 2022

People with a history of GBS can receive any currently recommended COVID-19 vaccine.

Last reviewed: November 16, 2024

In this case, it is preferable to refer to a vaccination provider who can administer either PCV20 or PCV21 alone or PCV15 with plans to receive PPSV23 one year later. ACIP recommends that PCV15 be administered before PPSV23 for optimal immune response to vaccination. If there is a challenge in finding another location where the patient can receive a recommended PCV option, it is better to give PPSV23 than nothing at all.

Last reviewed: November 13, 2024

While breakthrough infections can happen, it is very uncommon in an otherwise healthy young adult. In this scenario, it is unknown when the HBV infection occurred. It is possible that the person had an unrecognized exposure to hepatitis B virus at some time before they were vaccinated: they may even have been born to a hepatitis B-infected mother and infected at birth. This is the reason triple panel screening of every adult, regardless of vaccination history, is recommended. People who decline or defer screening but accept vaccination should understand that vaccination will not alter a pre-existing infection, which is why hepatitis B screening is important for everyone.

Last reviewed: July 21, 2023


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Last reviewed: December 7, 2023

The Occupational Safety and Health Administration (OSHA) requires that HepB be offered to healthcare personnel (HCP) who have a reasonable expectation of being exposed to blood and body fluids on the job. This requirement does not include personnel who would not be expected to have occupational risk (for example, general office workers). Employers must ensure that workers who decline HepB vaccination sign a declination form. For a fact sheet about this OSHA requirement, go to: www.osha.gov/OshDoc/data_BloodborneFacts/bbfact05.pdf.

As of April 2022, CDC recommends that all people younger than age 60 years be vaccinated against hepatitis B. All adults age 60 or over with risk factors for acquiring hepatitis B (including HCP expected to be exposed to blood and body fluids) also should be vaccinated. Any adult age 60 or older may be vaccinated.

Last reviewed: July 21, 2023


1:40

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Last reviewed: December 7, 2023

The ACIP HepB vaccine recommendations published in MMWR on January 12, 2018, remain in effect concerning vaccination of healthcare professionals, management of post-vaccination testing for evidence of immunity, revaccination considerations for nonresponders, and post-exposure management. Access these recommendations, beginning on page 18, at www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6701-H.pdf.

Last reviewed: July 21, 2023

The guidance for handling after reconstitution is the same for both brands of MMR vaccine (MMRII and Priorix). It is preferable to administer MMR immediately after reconstitution. If not used immediately, the reconstituted vaccine should be store refrigerated (2°C to 8°C [36°F to 46°F]) until use. If reconstituted MMR is not used within 8 hours, it must be discarded.

Last reviewed: June 19, 2023

Tdap is an inactivated vaccine and may be given at the same prenatal visit with RhoGam. For more information on this topic, including the timing for the use of other vaccines with regards to RhoGam, see ACIP’s “General Best Practice Guidelines” for Immunization at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html for more information on this issue.

Last reviewed: March 31, 2022

Recipients of mRNA COVID-19 vaccines often experience local (e.g., pain, swelling, redness at the injection site, localized swollen lymph nodes in the armpit of the vaccinated arm) or systemic (e.g., fever, fatigue, headache, chills, body and joint aches) post-vaccination symptoms. Depending on vaccine product (Pfizer-BioNTech vs. Moderna), age group, and vaccine dose, in clinical trials, approximately 80–91% of vaccinated people developed at least one local symptom and 55–91% developed at least one systemic symptom following vaccination.

Most systemic post-vaccination symptoms are mild to moderate in severity, occur within the first three days of vaccination, and resolve within 1–3 days of onset.

Among children ages 6 months through 4 years (Pfizer-BioNTech) or 6 months through 5 years (Moderna), pain or tenderness at the injection site was the most frequent local reaction noted in clinical trials. The most common systemic symptom in older children was fatigue; in younger children (ages 6 through 23 months), irritability/crying and drowsiness/sleepiness were most common. Most systemic symptoms were mild to moderate in severity, typically began 1 to 2 days after vaccination, and resolved after 1 to 2 days.

Last reviewed: November 16, 2024

Yes. If patients have an uncertain vaccination history and their records are not readily obtainable, you should administer the recommended doses: PCV20 or PCV21 alone or PCV15 followed by PPSV23 one year later. Extra doses will not cause harm to the patient. Per the CDC’s “General Best Practices for Immunization Guidelines”, self-reported doses of influenza and PPSV23 are acceptable. Therefore, if a patient remembers receiving PPSV23, it is acceptable to provide only one dose of PCV20, PCV21, or PCV15.

Last reviewed: November 13, 2024

The 2023 CDC recommendation is for all adults to have a triple panel screen for hepatitis B at least once in a lifetime. If the healthcare worker has never been screened, it would be ideal to do the triple panel screen in this situation.

Last reviewed: July 21, 2023

Yes. However, data are limited on the safety and immunogenicity effects when Heplisav-B or PreHevbrio is interchanged with HepB from other manufacturers. When feasible, the same manufacturer’s vaccines should be used to complete the series. However, vaccination should not be deferred when the manufacturer of the previously administered vaccine is unknown or when the vaccine from the same manufacturer is unavailable.

The 2-dose (4 weeks apart) HepB series only applies when both doses in the series consist of Heplisav-B. Series consisting of a combination of 1 dose of Heplisav-B and a vaccine from a different manufacturer should consist of 3 total vaccine doses and should adhere to the 3-dose schedule minimum intervals of 4 weeks between dose 1 and 2, 8 weeks between dose 2 and 3, and 16 weeks between dose 1 and 3. Doses administered at less than the minimum interval should be repeated. However, any series containing 2 doses of Heplisav-B administered at least 4 weeks apart is valid, even if the patient received a single earlier dose from another manufacturer.

Last reviewed: July 21, 2023

In clinical trials of Novavax COVID-19 Vaccine, pain or tenderness at the injection site was the most frequently reported local reaction among vaccine recipients; redness and swelling were reported less frequently. Fatigue, headache, and muscle pain were the most commonly reported systemic reactions. Most symptoms were mild to moderate in severity and resolved within 1 to 3 days. Overall, symptoms were more frequent in people ages 18 through 64 years compared to people ages 65 years and older and more frequent after dose 2 than dose 1.

Last reviewed: November 16, 2024

The minimal intervals for the 3-dose HepB vaccines are at least 4 weeks between doses #1 and #2, at least 8 weeks between doses #2 and #3, and at least 16 weeks between doses #1 and #3. Since in your cases 16 weeks or more have elapsed since dose #1, you should schedule dose #3 to be given 8 weeks after dose #2. It is not necessary to restart the series because of an extended interval between doses, no matter how long.

Last reviewed: July 21, 2023

Only the diluent supplied with the MMR vaccine should be used to reconstitute any vaccine. A vaccine reconstituted with the incorrect diluent should be repeated.

Last reviewed: June 19, 2023

A family history of a neurologic disorder or reaction to a pertussis-containing vaccine is not a contraindication to vaccination of this child. The child should receive additional DTaP doses as indicated in the catchup schedule.

Last reviewed: March 31, 2022

Yes. Many years of experience with Engerix-B and Recombivax HB brands of HepB vaccines indicate no apparent risk for adverse events to a developing fetus. Current HepB products contain noninfectious hepatitis B surface antigen (HBsAg) and should pose no risk to the fetus. If not vaccinated, a pregnant person may contract an HBV infection during pregnancy, which might result in severe disease for the newborn.

Available human data on Heplisav-B and PreHevbrio administered during pregnancy are insufficient to assess vaccine-associated risks in pregnancy. For this reason, until safety data are available for Heplisav-B or PreHevbrio, providers should continue to vaccinate people needing HepB during pregnancy with either Engerix-B or Recombivax HB. Pregnancy testing prior to vaccination is not recommended.

Mothers who breastfeed their babies and need HepB can be vaccinated. Although data are not available to assess the effects of Heplisav-B and PreHevbrio on breastfed infants or on maternal milk production and excretion, there is no theoretical risk to the infant and vaccination with any HepB product is acceptable.

Last reviewed: July 21, 2023

No. However, this person should receive PCV15, PCV20, or PCV21 one year after PPSV23 if he has no history or an unknown history of receiving a pneumococcal conjugate vaccine in the past.

Last reviewed: November 13, 2024

CDC discourages the practice of prefilling vaccine into syringes for several reasons, including:

  • The increased possibility of administration and dosing errors
  • The increased risk of inappropriate storage temperature
  • The probability of bacterial contamination
  • The probability of reducing the vaccine’s potency over time

Prefilling vaccine into syringes also violates basic medication administration guidelines, which state that an individual should administer only those medications he or she has prepared and drawn up.

Although pre-drawing vaccine is discouraged, a limited amount of vaccine may be pre-drawn in a mass vaccination clinic setting under the following conditions:

  • Only a single type of vaccine (for example, influenza) is administered at the mass vaccination clinic setting
  • Vaccine is not drawn up in advance of its arrival at the mass vaccination clinic site
  • These pre-drawn syringes are stored at temperatures appropriate for the vaccine
  • No more than 1 vial or 10 doses (whichever is greater) is drawn into syringes
  • Clinic staff monitor patient flow carefully and avoid drawing up unnecessary doses or delaying administration of pre-drawn doses

At the end of the clinic day, all remaining vaccine in syringes prefilled by staff should be discarded.

Last reviewed: August 11, 2024

All HCP, including trainees, who have a high risk of occupational percutaneous or mucosal exposure to blood or body fluids (for example, HCP with direct patient contact, HCP at risk of needlestick or sharps injury, laboratory workers who draw, test or handle blood specimens) should have postvaccination testing for antibody to hepatitis B surface antigen (anti-HBs). Postvaccination testing should be done 1–2 months after the last dose of vaccine. Postvaccination testing for individuals at low risk for mucosal or percutaneous exposure to blood or body fluids (for example, public safety workers and HCP without direct patient contact) likely is not cost-effective; however, those who do not undergo postvaccination testing should be counseled to seek immediate testing if exposed.

Last reviewed: July 21, 2023

This depends on the contraindication or precaution the person had to DTaP.

The contraindications are (1) severe allergic reaction (e.g., anaphylaxis after a previous dose or to a vaccine component) and (2) encephalopathy within 7 days of a previous dose of DTaP or DTP; in these cases, give Td instead of Tdap.

The precautions for which Tdap vaccination may be delayed or for which the balance of individual risks and benefits should be weighed are

  • Moderate or severe acute illness (defer until recovered);
  • History of an Arthus-type hypersensitivity reaction following a previous dose of tetanus or diphtheria toxoid-containing vaccines, including MenACWY-D or MenACWY-TT (Menactra or MenQuadfi, Sanofi Pasteur) (defer vaccination until at least 10 years have elapsed since the last tetanus-toxoid-containing vaccine);
  • Guillain-Barré syndrome (GBS) 6 weeks or sooner after a previous dose of tetanus toxoid-containing vaccine; and
  • Progressive or unstable neurologic disorder, uncontrolled seizures or progressive encephalopathy until a treatment regimen has been established and the condition has stabilized.

ACIP has published a Guide to Vaccine Contraindications and Precautions in its “General Best Practice Guidelines for Immunization”, available at www.cdc.gov/vaccines/hcp/imz-best-practices/contraindications-precautions.html.

Last reviewed: March 31, 2022

Vaccinating people against influenza who have recently tested positive for COVID-19 involves multiple considerations, such as whether vaccinating them could expose others to COVID-19, how sick they are, their risk for severe influenza illness, the ability to vaccinate at a later date, and the desire to avoid confusing postvaccination symptoms with those of COVID-19. Usually, people who are known to be infectious should not be brought to a vaccination setting if doing so could expose others to COVID-19. Any moderate or severe acute illness is a precaution to influenza vaccination: vaccination should generally be deferred until recovery. For people with mild or asymptomatic COVID-19, delaying vaccination also might be considered to avoid confusing COVID-19 symptoms with postvaccination reactions.

Last reviewed: August 11, 2024

It is preferable that the person planning to have the procedure be protected from pneumococcus at the time of the surgery; if possible, administer the appropriate vaccine at least two weeks in advance of the splenectomy or cochlear implant. If the procedure is done on an emergency basis, vaccinate as soon as possible after surgery. Adults who have not previously received any pneumococcal vaccine should receive either PCV20 or PCV21 alone or PCV15 followed by PPSV23 at least 8 weeks later.

Recommendations for vaccination of a child in this situation depends on the child’s age and pneumococcal vaccination history (number of doses and types of vaccine(s) received).  To evaluate the specific needs of the child, see CDC’s guidance at  www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/risk-indications.html or Immunize.org’s Recommendations for Pneumococcal Vaccination of Children and Teens at www.immunize.org/wp-content/uploads/catg.d/p2016.pdf. 

Last reviewed: November 13, 2024

There are two options for healthcare professionals who test negative after completing their first HepB series. The first option is to give one dose of HepB, then retest for anti-HBs. If the result is positive, the person should be considered immune. If negative, the person should receive the remaining doses in the series, and then retest for anti-HBs. If the result is positive, the person should be considered immune. If negative, the person should be tested for HBsAg and total anti-HBc to determine their HBV infection status.

People who test negative for HBsAg and total anti-HBc should be considered vaccine non-responders and susceptible to HBV infection. They should be counseled about precautions to prevent HBV infection and the need to obtain hepatitis B immune globulin (HBIG) prophylaxis for any known or likely exposure to HBsAg-positive blood. Those found to be HBsAg negative but total anti-HBc positive were infected in the past and require no vaccination or treatment. If the HBsAg and total anti-HBc tests are positive, the person should receive appropriate counseling for preventing transmission to others as well as referral for ongoing care to a specialist experienced in the medical management of chronic HBV infection. They should not be excluded from work.

The second option is to repeat the 2- or 3-dose series (depending on vaccine brand) and test for anti-HBs 1–2 months after the final dose of the repeat series. Heplisav-B or PreHevbrio may be used for revaccination following an initial HepB series that consisted of doses from a different manufacturer. Heplisav-B or PreHevbrio may also be used to revaccinate new healthcare personnel (including the challenge dose) initially vaccinated with a vaccine from a different manufacturer in the distant past who have anti-HBs less than 10 mIU/mL upon hire or matriculation.

If the test is still negative after a second vaccine series, the person should be tested for HBsAg and total anti-HBc to determine their HBV infection status. People who test negative for HBsAg and total anti-HBc should be considered vaccine non-responders and susceptible to HBV infection. They should be counseled about precautions to prevent HBV infection and the need to obtain hepatitis B immune globulin (HBIG) prophylaxis for any known or likely exposure to HBsAg-positive blood. Those found to be HBsAg negative but total anti-HBc positive were infected in the past and require no vaccination or treatment. If the HBsAg and total anti-HBc tests are positive, the person should receive appropriate counseling for preventing transmission to others as well as referral for ongoing care to a specialist experienced in the medical management of chronic HBV infection. They should not be excluded from work.

The choice of option 1 and option 2 should be based on epidemiologic considerations and likelihood that the patient is HBsAg positive, since there is a delay in option 1 in determining HBsAg status.

Last reviewed: July 21, 2023

Inactivated and recombinant influenza vaccines are not known to cause false positive nasal swab tests. The results may indicate real infections; however, false positive test results are possible with rapid tests, and these are more likely to occur if the tests are done when influenza prevalence in the area is low, such as early in the influenza season. For more information regarding interpretation of rapid influenza tests see www.cdc.gov/flu/professionals/diagnosis/rapidlab.htm.

Last reviewed: August 11, 2024

Controlled epilepsy is not a contraindication to receipt of Tdap. To review the true contraindications and precautions to vaccination, consult the appendix of the CDC Recommended Child and Adolescent Immunization Schedule (www.cdc.gov/vaccines/hcp/imz-schedules/child-adolescent-age.html). CDC also makes this information available at www.cdc.gov/vaccines/hcp/imz-best-practices/contraindications-precautions.html.

Last reviewed: February 19, 2024

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