This message was sent to AIM, FAB, Health Systems, INE, IAP, LHD Health Officers, LHD Medical Directors, MACI, MACI 2, PH Imms Leads, MCIR Region Contacts, COVID-19 Vaccine Providers, and Imms All Staff. I apologize for any duplicationsClick to edit this heading.

Dear Immunization Partners,

The Centers for Disease Control and Prevention (CDC) has published an MMWR article on Use of a Modified Preexposure Prophylaxis Vaccination Schedule to Prevent Human Rabies: Recommendations of the Advisory Committee on Immunization Practices dated May 6, 2022.

Human rabies is an acute, progressive encephalomyelitis that is nearly always fatal once symptoms begin. A small subset of persons has a higher level of risk for being exposed to rabies virus than does the general U.S. population; these persons are recommended to receive preexposure prophylaxis (PrEP), a series of human rabies vaccine doses administered before an exposure occurs, in addition to postexposure prophylaxis (PEP) after an exposure. PrEP does not eliminate the need for PEP; however, it does simplify the rabies PEP schedule (i.e., eliminates the need for rabies immunoglobulin and decreases the number of vaccine doses required for PEP).

Modifications to PrEP

• Redefined risk categories
• Fewer vaccine doses in the primary vaccination schedule
• Flexible options for ensuring long-term protection, or immunogenicity
• Less frequent or no antibody titer checks for some risk groups
• A new minimum rabies antibody titer (0.5 international units [IUs]) per mL)
• Clinical guidance, including for ensuring effective vaccination of certain special populations

Recommendations

For further guidance see: Rabies preexposure prophylaxis recommendations (table)

• Risk Category 1= elevated risk for unrecognized and recognized exposures including unusual or high-risk exposures:
  • 2 IM doses of human diploid cell vaccine (HDCV; Imovax/Sanofi Pasteur) or purified chick embryo cell vaccine (PCECV; RabAvert/Bavarian Nordic) on days 0 and 7, AND
  • Should have rabies antibody titers checked every 6 months; a booster dose should be administered if titers are <0.5 IU/mL at the time of these checks
• Risk Category 2= elevated risk for unrecognized and recognized exposures:
  • 2 IM doses of HDCV or PCECV on days 0 and 7, AND
  • Should have rabies antibody titers checked every 2 years; a booster dose should be administered if titers are <0.5 IU/mL at the time of these title checks
• Risk Category 3= elevated risk for recognized exposures, sustained risk:
  • 2 IM doses of HDCV or PCECV on days 0 and 7, AND either have
    • Rabies antibody titers checked during years 1–3 after completion of the 2-dose primary series (and a booster dose if the titer is <0.5 IU/mL), OR
    • Booster no sooner than day 21 and no later than year 3 after 2-dose primary series
• Risk Category 4= elevated risk for recognized exposures, risk not sustained:
  • 2 IM doses of HDCV or PCECV on days 0 and 7
• Risk Category 5= low risk for exposure:
  • No Primary PrEP recommendations

These recommendations apply both to immunocompetent and immunocompromised persons; however, PrEP administered to immunocompromised persons requires additional considerations as described in Clinical Guidance below.

Clinical Guidance

• Coadministration of IM rabies PrEP and chloroquine or drugs related to chloroquine
  • Out of an abundance of caution and because rabies is nearly always fatal, clinicians might consider avoiding chloroquine when rabies vaccine is being administered
  • If avoidance is not possible, ensuring that a patient’s rabies antibody titer is ≥0.5 IU/mL no sooner than 1 week (preferably 2–4 weeks) after completion of the series will confirm that vaccination was effective
• Approach to PrEP in special populations, including persons suspected or confirmed to be immunocompromised (can have a suboptimal immune response)
  • ACIP recommends that, when possible, vaccination be delayed until a temporary immunocompromising condition has resolved or immunosuppressive medications can be withheld
  • If an immunocompromising condition cannot be temporarily reversed, rabies vaccines can be administered, but antibody titer should be checked no sooner than 1 week (preferably 2-4 weeks) after completion of the 2-dose PrEP series and all booster doses
    • If the titer is <0.5 IU/mL, a booster dose should be administered, followed by a subsequent titer check
    • If two such booster doses fail to elicit an acceptable antibody titer, local or state public health authorities should be consulted for case-specific guidance
    • Participation in high-risk activities by persons confirmed or suspected to be immunocompromised should be avoided until the laboratory-confirmed minimum acceptable antibody titer is achieved or until public health authorities provide alternative guidance
    • If deviations in the ACIP recommendations occur as described in management of deviation section below, a titer check is recommended regardless of immune status
• Management of deviations from the recommendations
  • When substantial delays occur with the primary series, local and state public health authorities should be consulted for guidance
  • The second dose of the primary series should not be administered before the recommended interval between doses has elapsed; if it is inadvertently administered earlier, local and state public health authorities should be consulted for guidance

Thank you for all you do to protect Michiganders from vaccine preventable diseases.

Your Immunization Nurse Education Team,
Andrea, Dianne, Heidi, Sarah, and Terri