As an additional service to IZ Express readers, we periodically publish special editions such as this one, providing you with new and updated Ask the Experts questions and answers from Immunize​.org’s experts. This issue includes 5 Q&As about rabies vaccination, and 6 Q&As about scheduling or documenting vaccinations.  

A: Globally, about 59,000 human rabies deaths occur each year, and 98% of these deaths are caused by the canine (dog) rabies virus variant. In the United States, the canine rabies virus variant has been eliminated, but wildlife variants (such as bat, raccoon, and skunk rabies virus variants) remain. Hawaii is the only U.S. state that is rabies-free. About 5,000 animal cases of rabies are reported each year in the United States. In the 21-year period between January 2000 and December 2020, 52 cases of human rabies were diagnosed in the United States, and 38 of these were caused by rabies acquired in the United States. No U.S. cases occurred in people who had previously received rabies vaccine as pre-exposure prophylaxis. 

A: Two rabies vaccines are available in the United States. Both vaccines contain inactivated rabies virus. HDCV vaccine (Imovax, Sanofi) is produced in human diploid cell culture. PCECV vaccine (RabAvert, Bavarian Nordic) is produced in chick embryo cell culture. Both types are considered equally safe and effective. The products are interchangeable: it is acceptable to administer a mixed-brand series, if needed. 

A: In May 2022, CDC published new ACIP recommendations reducing the primary PrEP rabies vaccination series from 3 doses to 2 doses (administered intramuscularly on days 0 and 7) for all people at elevated risk for exposure to rabies. This was done based on strong evidence that the 2-dose schedule would provide the same protection as the previously recommended 3-dose primary series for up to three years. The less costly 2-dose schedule conserves rabies vaccine supplies, which have been subject to national shortages at times, and may increase adherence with PrEP recommendations. 

Five categories of risk were created based upon variables including elevated risk of unusual, unrecognized, or recognized exposures and whether elevated risk is sustained over time, or not. For individuals in risk categories 1–3 (all with sustained elevated risk expected to last more than 3 years after the primary series), ACIP recommends periodic rabies vaccine antibody titer checks at different intervals, and/or booster vaccination. See the table on pages 622–623 of the MMWR published on May 6, 2022, (www.cdc.gov/mmwr/volumes/71/wr/pdfs/mm7118a2-H.pdf) for each risk category's antibody titer and/or booster dose recommendations for sustained pre-exposure prophylaxis over time. 

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A: Treatment after an exposure (PEP) in a previously unvaccinated person requires receiving a dose of human rabies immune globulin (HRIG) and four (or five if the person's immune system is suppressed) doses of vaccine. Pre-exposure prophylaxis (PrEP) requires only two doses of vaccine and no immune globulin. If a person who is up to date with the recommended PrEP schedule is exposed to rabies, the person’s PEP treatment is completed with two doses of vaccine (on day 0 and day 3). 

A: As a general rule, infants or children who are more than 1 month or 1 dose behind schedule should be on an accelerated schedule, which means the intervals between doses should be reduced to the minimum allowable. Catch-up schedules for children ages 4 months through 18 years are included in Table 2 of each year's recommended immunization schedule for children and adolescents, approved by the ACIP, CDC, and all other major professional organizations of healthcare providers who care for children. To review Table 2, go to www.cdc.gov/vaccines/schedules/hcp/index.html and open the current schedule for children and adolescents. 

A: For intervals of 3 months or less, you should use 28 days (4 weeks) as a "month." For intervals of 4 months or longer, you should consider a month a "calendar month": the interval from one calendar date to the next a month later. This is a convention that was introduced on the childhood schedule in 2002 and discussed in the paper "Evaluation of Invalid Vaccine Doses" (Stokley S, Maurice E, Smith PJ, et al. American Journal of Preventive Medicine, 2004; 26[1]: 34–40). 

A: For routinely administered vaccines, there is no vaccine series that needs to be restarted because of an interval that is longer than recommended. In certain circumstances, oral typhoid vaccine (which may be given for international travel) needs to be restarted if the vaccine series isn't completed within the recommended time frame.