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 (1374)

The safety and effectiveness of Heplisav-B has 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: January 17, 2025


2:01

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Last reviewed: August 11, 2024

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

Last reviewed: June 25, 2023

No.

Last reviewed: August 11, 2024

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: November 16, 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

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: November 13, 2024

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: January 17, 2025

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

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: November 16, 2024

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: January 17, 2025

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: January 17, 2025

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 screening test 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: January 17, 2025


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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: January 17, 2025

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: January 17, 2025

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: January 17, 2025


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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: January 17, 2025

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: January 17, 2025

There are 3 different HepB vaccines currently available and approved for adults in the United States, 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 shows 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.

Any available HepB vaccine may be used when vaccinating during pregnancy.

Last reviewed: January 17, 2025


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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: January 17, 2025

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: January 17, 2025

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: January 17, 2025

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: January 17, 2025


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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: January 17, 2025


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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: January 17, 2025


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: January 17, 2025

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: January 17, 2025

Yes. However, data are limited on the safety and immunogenicity effects when Heplisav-B 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) complete 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 an earlier dose from another manufacturer.

Last reviewed: January 17, 2025

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

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