Ask the Experts: All Questions

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Results (1317)

No serious adverse events have been attributed definitively to HepA vaccine. Among adults, the most frequently reported side effects are soreness at the site of the injection and headache. In children, the most frequently reported side effect is soreness at the injection site. The frequency of side effects after administration of Twinrix is similar to those reported when the two single-antigen vaccines were administered.

Last reviewed: June 25, 2023

If you stock PCV15 and plan to use the PCV15 and PPSV23 combined series to vaccinate patients for whom this is an option, you should always give the PCV15 first. PCV is always recommended to be given before PPSV23, based on studies demonstrating a better immune response to serotypes common to both vaccines when PCV is given first. These vaccines should not be given at the same visit.

The routine interval between PCV15 and PPSV23 is one year; however, PPSV23 may be administered a minimum of 8 weeks after PCV15 when the recipient has an immunocompromising condition, cochlear implant, or cerebrospinal fluid leak. If PPSV23 is inadvertently administered first, wait a minimum of one year to administer any PCV, because there is evidence that the immune response to a PCV is diminished when PCV is administered soon after PPSV23.

Last reviewed: April 5, 2024

Contraindications are:
• a history of severe allergic reaction to a vaccine component (except egg) or after a previous dose of any influenza vaccine (people with egg allergy of any severity may receive LAIV if it is otherwise appropriate for their age and health status)
• concomitant aspirin or salicylate-containing therapy in children and adolescents because of the risk of Reye syndrome
• children age 2 through 4 years who have received a diagnosis of asthma or whose parents or caregivers report that a healthcare provider has told them during the preceding 12 months that their child had wheezing or asthma or whose medical record indicates a wheezing episode during the preceding 12 months
• immunosuppression due to any cause including medications or HIV infection
• cerebral spinal fluid (CSF) leak, cochlear implant, or anatomic asplenia or functional asplenia (e.g., due to sickle cell anemia)
• close contacts and caregivers of severely immunosuppressed people who require a protected environment (e.g., reverse isolation in a hospital)
• pregnancy
• receipt of influenza antiviral medication within the previous 48 hours (oseltamivir or zanamivir), previous 5 days (peramivir), or previous 17 days (baloxavir)

Precautions are:
• moderate or severe acute illness with or without fever (defer)
• history of Guillain-Barré syndrome within 6 weeks after a dose of influenza vaccine
• asthma in a person age 5 years or older
• underlying medical conditions that might predispose to complications after influenza virus infection, such as chronic pulmonary, cardiovascular (except isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders including diabetes mellitus

Last reviewed: September 10, 2023

When using Engerix-B or Recombivax HB brands of HepB to vaccinate hemodialysis or other immunocompromised people, a higher dose is recommended, so to the extent these patients are immunocompromised, this is within ACIP recommendations (note that “immunocompromised” is not defined in the recommendations). Regardless, this practice is appropriate for several reasons, including that these patients may be starting hemodialysis soon, and because use of the higher dose is not harmful. This is somewhat of a gray area but the clinician can use clinical judgment. Heplisav-B and PreHevbrio have not been evaluated for use in dialysis or pre-dialysis patients.

Last reviewed: July 21, 2023

History of an anaphylactic reaction to a dose of mRNA COVID-19 vaccine is a contraindication to receipt of further doses of mRNA-type COVID-19 vaccines. However, a person with a contraindication to one type of COVID-19 vaccine (mRNA) may receive the alternative COVID-19 vaccine type (in this case, the adjuvanted protein subunit vaccine by Novavax) in the usual vaccination setting. CDC encourages consultation with an allergist-immunologist to provide expert evaluation of the original allergic reaction, and depending on the outcome of that evaluation, reassess whether administration of additional doses of the original vaccine type may be possible.

Last reviewed: March 19, 2024

In general, a child should receive no more than four doses of DTaP before 4 years of age (preferably by 2 years of age). The ACIP recommends that a dose of DTaP be given at 4–6 years of age. Many states have school immunization laws which also require at least one dose of DTP/DTaP on or after the fourth birthday. This dose is important to boost immunity to pertussis.

Last reviewed: March 31, 2022

MMR can be administered any time after delivery. The vaccine should be administered to a post-partum mother who is susceptible to either measles, mumps, or rubella before hospital discharge, even if the mother has received RhoGam during the hospital stay, leaves in less than 24 hours, or is breastfeeding.

Last reviewed: June 19, 2023

Hepatitis A vaccine is contraindicated for people with a history of a severe allergic reaction to a previous dose of HepA vaccine or to a vaccine component. As with all other vaccines, there is a precaution when giving it to anyone who is moderately or severely ill.

Last reviewed: June 25, 2023

The 2023 influenza ACIP recommendations state that everyone 6 months of age or older with egg allergy should receive an influenza vaccine. Any influenza vaccine (egg based or non-egg based) appropriate for the person’s age and health status can be used.

Egg allergy alone does not require any additional safety measures for influenza vaccination beyond those recommended for any recipient of any vaccine. All vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are available.

A person who has had a previous severe allergic reaction to an influenza vaccine has a contraindication to future receipt of that vaccine. For a complete list of vaccine components (i.e., excipients and culture media) used in the production of the vaccine, check the package insert (available at www.immunize.org/fda) or go to www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/excipient-table-2.pdf.

For more on the evidence and rationale supporting the change in recommendations regarding influenza vaccination and egg allergy, see pages 12 and 13 of the published ACIP recommendations for the 2023–24 season at www.cdc.gov/mmwr/volumes/72/rr/pdfs/rr7202a1-H.pdf.

Last reviewed: September 10, 2023

No, PCV15 and PPSV23 vaccines should not be given at the same visit. When administering PCV15 followed by PPSV23, give PCV15 first followed by PPSV23 one year later. Providers can consider waiting a minimum interval of 8 weeks to give PPSV23 to people with immunocompromising conditions, cochlear implant, or cerebrospinal fluid (CSF) leak.

If a patient inadvertently received PPSV23 before PCV15, a minimum interval of at least 1 year between doses is recommended and a shorter interval is not recommended.

Last reviewed: April 5, 2024

This condition is not rare and is sometimes referred to as “COVID arm”. Future doses should be given as recommended. Individuals with only a delayed-onset local reaction (e.g., redness, induration, itching) around the injection site area after an mRNA vaccine dose do not have a contraindication or precaution to subsequent doses. Consider administering the next dose in the opposite arm, if possible.

These delayed-onset local reactions are sometimes quite large but are self-limited. It is not known whether individuals who experienced a delayed-onset injection site reaction after one dose will experience a similar reaction after future doses. These reactions are not believed to represent an increased risk for anaphylaxis after future doses.

Patients who experience “COVID arm” may take an antihistamine if it is itchy or a pain medication, such as acetaminophen or a non-steroidal anti-inflammatory (NSAID), if it is painful.

Last reviewed: March 19, 2024

ACIP and AAP both recommend that children receive no more than 6 doses of diphtheria and tetanus toxoids (e.g., DT, DTaP, DTP) before the seventh birthday because of concern about adverse reactions, primarily local reactions. Half doses of DTaP are also not recommended under any circumstances, and should not be counted as part of the vaccination series. Only documented doses (i.e., those recorded in an electronic or written record) count toward the maximum of 6 doses.

Last reviewed: March 31, 2022

Yes. ACIP recommends that pregnant women at risk for HAV infection during pregnancy or at risk for a severe outcome from HAV infection should be vaccinated during pregnancy if not previously vaccinated. Pregnant women should be vaccinated for the same indications as non-pregnant women. For additional details, see page 20 of the current ACIP recommendations: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.

Last reviewed: June 25, 2023

No. This issue has been studied extensively, including a thorough review by the independent Institute of Medicine (IOM). The IOM issued a report in 2004 that concluded there is no evidence supporting an association between MMR vaccine or thimerosal-containing vaccines and the development of autism. For more information on thimerosal and vaccines in general, visit www.cdc.gov/vaccinesafety/Concerns/thimerosal/index.html.

Last reviewed: June 19, 2023

The safety and effectiveness of Heplisav-B and PreHevbrio have not been established for adult patients on hemodialysis. ACIP recommendations only address the use of Engerix-B or Recombivax HB in this population at this time.

Last reviewed: July 21, 2023

Give PCV15 first, at least 8 weeks after the most recent dose of PCV, followed by PPSV23 at least 8 weeks later. PCV15 and PPSV23 should not be given at the same visit. If a child has already received PPSV23, wait at least 8 weeks before giving PCV15 or PCV20 to the child.

Last reviewed: April 5, 2024

Merck no longer produces single antigen measles, mumps, and/or rubella vaccines for the U.S. market. Only combined MMR is available. You should educate parents about the lack of association between MMR and autism. You may provide parents with Immunize.org’s parent handout (developed in collaboration with the Autism Science Foundation): Evidence Shows Vaccines Unrelated to Autism, found at www.immunize.org/catg.d/p4028.pdf.

Last reviewed: June 19, 2023

No.

Last reviewed: September 10, 2023

Twinrix (GSK) is an inactivated combination vaccine containing both hepatitis A virus (HAV) and HBV antigens. The vaccine contains 720 EL.U. of hepatitis A antigen (half of the Havrix adult dose) and 20 mcg of hepatitis B antigen (the full Engerix-B adult dose). In the United States, Twinrix is licensed for use in people who are age 18 years or older. It can be administered to people who are at risk for hepatitis A and who are recommended to receive hepatitis B vaccination, such as certain international travelers, people with chronic liver disease, men who have sex with men, people who use drugs, or to people who want to be immune to both diseases.

A standard Twinrix series consists of 3 doses given intramuscularly on a 0, 1, and 6 month schedule.

In March 2007, the FDA approved a 4-dose schedule for Twinrix. It consists of 3 doses given within 3 weeks, followed by a booster dose at 12 months (0, 7 days, 21 to 30 days, and 12 months). The 4-dose schedule could benefit individuals needing rapid protection from hepatitis A and hepatitis B, such as some people traveling imminently. Twinrix cannot be used for post-exposure prophylaxis.

Last reviewed: July 21, 2023

The minimum interval between DTaP #4 and DTaP #5 is six months. Remember that the minimum age for DTaP #5 is age 4 years.

Last reviewed: March 31, 2022

Medications to reduce fever and pain (e.g., acetaminophen, non-steroidal anti-inflammatory drugs) may be taken to treat post-vaccination local or systemic symptoms, if medically appropriate. However, routine administration of such medications before vaccination is not recommended because information on the potential impact of such use on COVID-19 vaccine-induced antibody responses is not available at this time.

Administration of antihistamines before COVID-19 vaccination to prevent allergic reactions is not recommended. Antihistamines do not prevent anaphylaxis, and their use might mask cutaneous symptoms, which could delay diagnosis and management of anaphylaxis.

Last reviewed: March 19, 2024

Yes. HepA vaccine is an inactivated vaccine and poses no harm to the nursing infant.

Last reviewed: June 25, 2023

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: April 5, 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, and 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/vaccinesafety/concerns/febrile-seizures.html.

Last reviewed: September 10, 2023

Arthralgia (joint pain) and transient arthritis (joint redness or swelling) following rubella vaccination occurs only in people who were susceptible to rubella at the time of vaccination. Joint symptoms are uncommon in children and in adult biological males. About 25% of non-immune post-pubertal biological females report joint pain after receiving rubella vaccine, and about 10% to 30% report arthritis-like signs and symptoms.

When joint symptoms occur, they generally begin 1 to 3 weeks after vaccination, usually are mild and not incapacitating, last about 2 days, and rarely recur.

Last reviewed: June 19, 2023

If DTaP is not contraindicated and the child has not received all of the age-appropriate doses of pertussis-containing vaccine, it would be best to try to administer as many doses of DTaP as possible before the child reaches his 7th birthday in order to confer protection against pertussis. Give additional doses of DTaP with 4-week intervals until you achieve 3 total doses. Then, give additional doses with 6-month intervals, not to exceed 6 total doses of diphtheria- and tetanus-containing vaccine by the child’s 7th birthday.

Last reviewed: March 31, 2022

The COVID-19 vaccines currently available in the United States (mRNA vaccines and the Novavax protein subunit vaccine) are not contraindicated in patients with a history of TTS. The Janssen COVID-19 vaccine associated with immune-mediated TTS in the United States is no longer available.

Last reviewed: March 19, 2024

Yes. All people age 1 year or older living with HIV infection should be vaccinated against hepatitis A if they have not been vaccinated, regardless of their CD4+ count.

If any immunocompromised person has a risk factor that places them at increased risk of hepatitis A (e.g., international travel, drug use), they should be vaccinated with HepA vaccine.

Last reviewed: June 25, 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: September 10, 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 PCV13 or PCV15 and PPSV23 is 1 year, and the minimum interval is 8 weeks.

Last reviewed: April 5, 2024

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

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

Last reviewed: June 25, 2023

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

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: April 5, 2024

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: March 19, 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

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

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: September 10, 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

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

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

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

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

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

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/schedules/hcp/imz/adult.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

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: April 5, 2024

Both the inactivated and recombinant influenza vaccine VIS and the live influenza vaccine VIS were updated on August 6, 2021. These VISs and translations in multiple languages are available here: www.immunize.org/vis/.

Last reviewed: September 10, 2023

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: March 19, 2024

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

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

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

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: March 19, 2024

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

Last reviewed: April 5, 2024

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

Last reviewed: March 19, 2024

Immunize.org has a 1-page printable document that summarizes each of the products available for the current influenza vaccination season, including age indications, at www.immunize.org/catg.d/p4072.pdf.

Last reviewed: September 10, 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

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

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

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

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