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Issue 1409: February 4, 2019
Ask the Experts: CDC Experts Answer Your Questions
As a thank-you to our loyal IAC Express readers, we periodically publish extra editions such as this one, with new and updated "Ask the Experts" Q&As answered by CDC experts.
IAC extends thanks to our experts: Andrew T. Kroger, MD, MPH; Candice L. Robinson, MD, MPH; Raymond A. Strikas, MD, MPH, FACP, FIDSA; Mark S. Freedman, DVM, MPH, DACVPM; Tina S. Objio, MSN, MHA, RN; and JoEllen Wolicki, BSN, RN, all from the National Center for Immunization and Respiratory Diseases, CDC.
HPV Vaccine
Hepatitis A Vaccines
Varicella Vaccine
Varicella Zoster Immune Globulin
Zoster Vaccines
HPV Vaccine
Q: Please describe the HPV vaccines available in the United States.
A: Gardasil 9 (9vHPV, Merck) is the only HPV vaccine being distributed in the United States. Bivalent Cervarix (2vHPV, GSK) and quadrivalent Gardasil (4vHPV, Merck) are no longer being distributed in the United States.
9vHPV is an inactivated 9-valent vaccine licensed by the Food and Drug Administration (FDA) in 2014. It contains 7 oncogenic (cancer-causing) HPV types (16, 18, 31, 33, 45, 52 and 58) and two HPV types that cause most genital warts (6 and 11). The 9vHPV vaccine is licensed for females and males age 9 through 45 years.
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Q: What are the recommendations for use of HPV vaccine?
A: The Advisory Committee on Immunization Practices (ACIP) recommends that routine HPV vaccination be initiated for females and males at age 11 or 12 years. The vaccination series can be started as early as age 9 years. Vaccination is also recommended for females age 13 through 26 years and for males age 13 through 21 years who have not been vaccinated previously or who have not completed the vaccination series. In addition, vaccination is recommended for men age 22 through 26 years who have sex with men or are immunocompromised as a result of infection (including HIV), disease, or medication. Other males 22 through 26 years of age may be vaccinated. Although the vaccine is approved by the FDA for males and females through age 45 years, ACIP does not recommend routine vaccination of persons older than 26 years at this time.
Ideally, HPV vaccine should be administered before potential exposure to HPV through sexual contact. The most current ACIP recommendations for HPV vaccine are available at www.cdc.gov/mmwr/volumes/65/wr/mm6549a5.htm.
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Q: If a 30-year-old female patient insists that she wants to receive HPV vaccine, can I give it to her?
A: HPV vaccine is approved for use in men and women through age 45 years. However, ACIP does not recommend routine use of this vaccine for persons older than 26 years. Clinicians may administer HPV vaccine to men and women through age 45 years if they believe the vaccine will benefit the patient.
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Hepatitis A Vaccines
Q: Who is recommended to receive hepatitis A vaccine?
A: The Advisory Committee on Immunization Practices (ACIP) recommends routine hepatitis A vaccination for the following groups:
- All children at age 1 year (12–23 months). Children who have not received the second dose by age 2 years should be vaccinated as soon as feasible. Additionally, hepatitis A vaccine is recommended for children older than 23 months who live in areas where vaccination programs target older children, or who are at increased risk for infection, or for children, adolescents, and adults in whom immunity against hepatitis A is desired.
- People age 6 months or older who are traveling to or working in an area of the world except the United States, Canada, Japan, New Zealand, and Australia. Some (but not all) countries of Western Europe are also low risk. See the CDC Yellow Book at wwwnc.cdc.gov/travel/yellowbook/2018/infectious-diseases-related-to-travel/hepatitis-a for more information. When in doubt, vaccinate.
- Men who have sex with men
- Users of illegal drugs, injectable or noninjectable
- Homeless people
- Previously unvaccinated people who anticipate having close personal contact with an international adoptee from a country of high or intermediate endemicity during the first 60 days following the adoptee's arrival in the U.S.
- People who have blood clotting disorders
- People who work with HAV-infected nonhuman primates or with HAV in a research laboratory setting (No other groups have been shown to be at increased risk for HAV infection because of occupational exposure)
- People with chronic liver disease
- Any person who wishes to be immune to hepatitis A
Hepatitis A vaccine is not routinely recommended because of occupational exposure for healthcare personnel, sewage workers, or day care providers.
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Q: For hepatitis A vaccination, the recommended interval between the 2-dose series is at least 6 months. Is this the same as 24 weeks?
A: No. The recommended interval between dose #1 and #2 of hepatitis A vaccine is 6 calendar months, not 24 weeks.
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Q: What are the recommendations for postexposure prophylaxis (PEP) for hepatitis A?
A: Revised recommendations for hepatitis A postexposure prophylaxis were published in 2018. These recommendations are available at www.cdc.gov/mmwr/volumes/67/wr/pdfs/mm6743a5-H.pdf.
Healthy people who have completed the 2-dose hepatitis A vaccination series at any time do not need additional postexposure prophylaxis if they are exposed to hepatitis A virus. People who have recently been exposed to HAV and who have not previously received hepatitis A vaccine should receive PEP as soon as possible, within 2 weeks of exposure.
People age 12 months and older exposed to HAV within the past 14 days and who have not previously completed the 2-dose hepatitis A vaccine series should receive a single dose of hepatitis A vaccine as soon as possible. In addition to vaccine, immune globulin (IG; 0.1 mL/kg) may be administered to people older than 40 years of age, depending on the providers’ risk assessment (see stacks.cdc.gov/view/cdc/59777 for additional information). For long-term immunity, the hepatitis A vaccine series should be completed with a second dose at least 6 months after the first dose. However, the second dose is not necessary for PEP. A second dose should not be administered sooner than 6 calendar months after the first dose, regardless of HAV exposure risk.
People age 1 year or older who are immunocompromised or have chronic liver disease, and who have been exposed to HAV within the past 14 days and have not previously completed the 2-dose hepatitis A vaccination series, should receive both IG (0.1 mL/kg) and hepatitis A vaccine at the same visit in a different anatomic site (for example, separate limbs) as soon as possible after exposure. For long-term immunity, the hepatitis A vaccination series should be completed with a second dose at least 6 months after the first dose. However, the second dose is not necessary for PEP. A second dose should not be administered sooner than 6 calendar months after the first dose, regardless of HAV exposure risk. In addition to hepatitis A vaccine, IG should be considered for postexposure prophylaxis for persons with special risk factors for either HAV infection or increased risk of complications in the event of an exposure to HAV (see stacks.cdc.gov/view/cdc/59777 for additional information).
Twinrix (HepA-HepB; GSK) should not be used for PEP, but may be used to confer protection to at-risk, but not yet exposed, people during an outbreak.
Infants younger than 12 months of age and persons for whom vaccine is contraindicated should receive IG (0.1 mL/kg) instead of hepatitis A vaccine as soon as possible and within 2 weeks of exposure. MMR and varicella vaccines should not be administered sooner than 3 months after IG administration.
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Q: ACIP now recommends routine hepatitis A vaccination for people experiencing homelessness. Can you provide a definition of "experiencing homelessness"?
A: The U.S. Department of Health and Human Services defines a person experiencing homelessness as an individual who lacks housing (without regard to whether the individual is a member of a family), including an individual whose primary residence during the night is a supervised public or private facility (e.g., shelters) that provides temporary living accommodations, or an individual who is a resident in transitional housing. An individual without permanent housing may live on the street, stay in a shelter, mission, single-room occupancy facility, abandoned building, vehicle, or in any other unstable or non-permanent situation.
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Q: To complete a 21-year-old patient's hepatitis A vaccine series, how many adult doses should I give if the patient received a single dose of pediatric hepatitis A vaccine 5 years ago?
A: A person should receive the dosage of hepatitis A vaccine appropriate for their age at the time of administration. You should give the patient one adult dose of hepatitis A vaccine to complete the 2-dose series. It is not necessary to restart the vaccine series.
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Q: Which travelers are recommended to receive hepatitis A vaccine?
A: Hepatitis A vaccination is recommended for people age 6 months or older who are traveling to or working in an area of the world except the United States, Canada, Japan, New Zealand, and Australia. Some (but not all) countries of Western Europe are also low risk. See the CDC Yellow Book at wwwnc.cdc.gov/travel/yellowbook/2018/infectious-diseases-related-to-travel/hepatitis-a for more information. When in doubt, vaccinate.
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Q: What are the hepatitis A vaccination recommendations for vaccination of travelers to protect them from HAV infection?
A: ACIP revised its recommendations for preexposure hepatitis A vaccination for travelers in 2018 to include vaccination of infants 6 through 11 months of age (see www.cdc.gov/mmwr/volumes/67/wr/pdfs/mm6743a5-H.pdf). The travel-related dose for infants 6–11 months of age should not be counted toward the routine 2-dose series. The routine 2-dose hepatitis A vaccination series should be initiated at age 12 months according to the routine, age-appropriate vaccination schedule.
Healthy people age 12 months through 40 years who are planning travel to an area with high or intermediate HAV endemicity and have not received hepatitis A vaccine should receive a single dose of hepatitis A vaccine as soon as travel is considered and should complete the 2-dose series according to the routine schedule.
People with chronic liver disease as well as adults older than 40 years of age, immunocompromised persons, and persons with other chronic medical conditions planning to depart to an area with high or intermediate HAV endemicity in less than 2 weeks should receive the initial dose of hepatitis A vaccine, and also simultaneously may be administered IG at a separate anatomic injection site (for example, in separate limbs). In addition to hepatitis A vaccine, IG should be considered before travel for persons with special risk factors for either HAV infection or increased risk for complications in the event of an exposure to HAV. For more information on this issue see stacks.cdc.gov/view/cdc/59778.
Infants younger than 6 months and travelers who elect not to receive vaccine, or for whom vaccine is contraindicated, should receive a single 0.1 mL/kg dose of IG before travel when protection against HAV is recommended. If travel is for more than 1 month, a dose of 0.2 mL/kg should be administered. A 0.2 mL/kg dose can be repeated every 2 months for travel of more than 2 months duration.
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Q: Can Twinrix (HepA-HepB; GSK) be used for people planning international travel?
A: Yes, if time to travel allows, you can use the standard Twinrix schedule of 3 doses given intramuscularly on a 0-, 1-, and 6-month schedule. If travel is imminent, the accelerated 4-dose Twinrix schedule can be used, which is 3 doses given on days 0, 7 and 21–30 days, and a booster dose at 12 months.
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Q: How should hepatitis A vaccine be stored?
A: 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.
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Varicella Vaccine
Q: Can varicella vaccine be used as postexposure prophylaxis for a 9-month-old who was exposed to herpes zoster?
A: Varicella vaccine is neither licensed nor recommended for children younger than age 12 months. Assuming that the child is not immunocompromised, varicella zoster immune globulin (VZIG) is also not recommended. If the child has a condition which is considered to place the child at greater risk for complications than the general population, then VZIG could be considered (see www.cdc.gov/mmwr/pdf/wk/mm6228.pdf, pages 574–6).
ACIP does not have a recommendation for the use of acyclovir for varicella postexposure prophylaxis. The American Academy of Pediatrics provides some guidance on this issue in the current edition of the Red Book.
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Q: A 10-year-old girl came to our immunization clinic, and the nurse noted crusted lesions on her arms and legs. The parent said the child had chickenpox a week earlier. The girl was not ill, so we administered the vaccines she needed. But now I wonder if her recent case of chickenpox might interfere with her immune response to vaccines.
A: A previous history of chickenpox disease, even recent disease, is not known to interfere with the immune response to different vaccines. To review the true contraindications and precautions to vaccination, consult IAC's "Guide to Contraindications and Precautions to Commonly Used Vaccines" at www.immunize.org/catg.d/p3072a.pdf. Another helpful resource is ACIP's General Best Practice Guidelines for Immunization. It contains a useful table titled "Conditions incorrectly perceived as contraindications or precautions to vaccination (i.e., vaccines may be given under these conditions)". The table is available at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/contraindications.html, Table 4-2.
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Q: How should varicella vaccine be stored in my clinic?
A: Live varicella-containing vaccines (varicella, MMRV, live zoster) must be stored in a freezer at a temperature between -50°C and -15°C (between -58°F and +5°F) until reconstitution and administration. These vaccines can deteriorate rapidly after they are removed from the freezer. A separate stand-alone freezer should be used to store frozen vaccines that require storage temperatures between -50°C and -15°C (between -58°F and +5°F). A stand-alone storage unit that is frost-free or has an automatic defrost cycle is preferred. Frozen vaccines should not be stored in the freezer compartment of a combination unit because household freezers cannot maintain proper storage temperatures for frozen vaccines. This applies to both temporary and long-term storage of frozen vaccines. The diluents should be kept separately in the refrigerator or at room temperature. All live varicella-containing vaccines must be administered within 30 minutes of reconstitution.
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Q: I was told by a coworker that varicella vaccine can be stored at refrigerator temperature for up to three days and still be used. Is this true?
A: According to the manufacturer, unreconstituted varicella vaccine may be stored at refrigerator temperature (2°C to 8°C, 36°F to 46°F) for up to 72 continuous hours prior to reconstitution. Vaccine stored at 2°C to 8°C that is not used within 72 hours of removal from -15°C (+5°F) storage should be discarded. See www.merck.com/product/usa/pi_circulars/v/varivax/varivax_pi.pdf.
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Varicella Zoster Immune Globulin
Q: What is varicella zoster immune globulin (VZIG)?
A: VZIG is a human blood product prepared from plasma obtained from healthy, volunteer blood donors identified by routine screening to have high antibody titers to varicella-zoster virus. It first became available in 1978. In a study of immunocompromised children who were administered VZIG within 96 hours of varicella exposure, approximately one in five exposed children developed clinical varicella, and one in 20 developed subclinical disease compared with 65%–85% attack rates among historical controls.
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Q: In what circumstances should I consider giving VZIG?
A: According to CDC, the decision to administer VZIG depends on three factors: 1) whether the patient lacks evidence of immunity to varicella, 2) whether the exposure is likely to result in infection, and 3) whether the patient is at greater risk for varicella complications than the general population. For high-risk patients who have additional exposures to varicella-zoster virus 3 weeks or longer after initial VZIG administration, another dose of VZIG should be considered. The most recent ACIP recommendations for the use of VZIG were published in 2013 and are available at www.cdc.gov/mmwr/pdf/wk/mm6228.pdf, pages 574–6.
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Q: Which groups of patients are eligible for VZIG?
A: VZIG is recommended for patients without evidence of immunity to varicella who are at high risk for severe varicella and its complications, who have been exposed to varicella or herpes zoster, and for whom varicella vaccine is contraindicated. Patient groups recommended by CDC to receive VZIG include the following:
- Immunocompromised patients without evidence of immunity
- Newborn infants whose mothers have signs and symptoms of varicella around the time of delivery (i.e., 5 days before to 2 days after)
- Hospitalized preterm infants born at 28 weeks or more of gestation whose mothers do not have evidence of immunity to varicella
- Hospitalized preterm infants born at less than 28 weeks of gestation or who weigh 1,000 grams or less at birth, regardless of their mothers' evidence of immunity to varicella
- Pregnant women without evidence of immunity
CDC recommends administration of VZIG as soon as possible after exposure to varicella-zoster virus and within 10 days.
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Q: What is the recommended dosage of VZIG?
A: VZIG is supplied in 125-IU vials and should be administered intramuscularly as directed by the manufacturer. The recommended dose is 125 IU/10 kg of body weight, up to a maximum of 625 IU (five vials). The minimum dose is 62.5 IU (0.5 vial) for patients weighing 2.0 kg or less and 125 IU (one vial) for patients weighing 2.1–10.0 kg. VZIG is distributed by Saol Therapeutics Inc. For ordering information see varizig.com/liquid-product_info.html.
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Zoster Vaccines
Q: How are zoster vaccines administered?
A: Reconstitute recombinant zoster vaccine (RZV; Shingrix; GSK) using only the adjuvant solution provided. After reconstitution, administer RZV immediately by the intramuscular route or store the reconstituted vaccine refrigerated between 2° and 8°C (36° and 46°F) and use within 6 hours. Discard reconstituted vaccine if not used within 6 hours or if frozen. If RZV is reconstituted with other than the supplied adjuvant solution, it should be repeated. The dose can be repeated immediately. There is no interval that must be met between these doses.
Reconstitute zoster vaccine live (ZVL; Zostavax; Merck) using only the diluent provided. Administer ZVL by the subcutaneous route immediately after reconstitution to minimize loss of potency. If the vaccine is not administered within 30 minutes of reconstitution, it must be discarded.
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Q: A patient was inadvertently given RZV by the subcutaneous rather than the intramuscular route. Does the dose need to be repeated?
A: RZV (Shingrix) has been shown to be immunogenic when given by the subcutaneous route. A dose erroneously given by this route does not need to be repeated.
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Q: When reconstituted, the volume of ZVL is 0.65 mL. Should 0.65 mL or 0.5 mL be administered to the patient?
A: The recommended dose for ZVL (Zostavax) is the fully reconstituted amount, 0.65 mL.
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Q: When reconstituted, the volume of RZV is more than 0.5 mL. Should the entire volume of reconstituted vaccine be administered or just 0.5 mL as indicated in the package insert?
A: The RZV (Shingrix) adjuvant solution may contain up to 0.75 mL of liquid. The entire volume of the adjuvant solution should be withdrawn and used to reconstitute the lyophilized RZV vaccine. After mixing, withdraw the recommended dose of 0.5 mL. Any reconstituted vaccine left in the vial should be discarded.
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Q: We inadvertently gave ZVL rather than RZV. Can the dose of ZVL be counted as the first dose of the RZV series?
A: No. Doses of ZVL (Zostavax) cannot be counted towards completing the RZV (Shingrix) series. In this case, the first dose of RZV (Shingrix) should be given at least 8 weeks after the dose of ZVL (Zostavax) that was administered.
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Q: While giving a dose of RZV (Shingrix), the syringe came loose from the needle and part of the dose was lost. Will the patient be protected with this partial dose or does it need to be repeated?
A: A dose less than the full 0.5 mL dose is not valid and should be repeated. If the patient is still in the office, the dose can be repeated immediately. If the repeat dose cannot be given on the same day, CDC recommends that it should be given 4 weeks after the invalid dose.
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Q: My medical assistant inadvertently administered a 0.5 mL dose of the RZV (Shingrix) diluent only. The dose did not contain any antigen. When can we administer a properly reconstituted dose?
A: The CDC zoster subject matter experts recommend that in this situation you should wait 4 weeks before giving a repeat dose.
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Q: Several doses (antigen and diluent) of RZV were mistakenly stored in our office freezer. One of these doses was administered to a patient. Is this dose valid and if not, when can it be repeated?
A: Any RZV (Shingrix), either antigen or diluent, that is exposed to freezing temperature should not be used. If a dose exposed to freezing temperature is given to a patient, the dose should be considered invalid and should be repeated 4 weeks after the invalid dose.
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How to submit a question to Ask the Experts
IAC works with CDC to compile new Ask the Experts Q&As for our publications based on commonly asked questions. We also consider the need to provide information about new vaccines and recommendations. Most of the questions are thus a composite of several inquiries.
You can email your question about vaccines or immunization to IAC at admin@immunize.org.
As we receive hundreds of emails each month, we cannot promise that we will print your specific question in our Ask the Experts feature. However, you will get an answer.
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