People with ongoing occupational exposure to lyssaviruses are recommended to receive booster doses of rabies vaccine
Booster doses of rabies vaccine are recommended for immunised people who have ongoing occupational exposure to lyssaviruses in Australia or overseas.9,11,21-23 See Figure. Booster algorithm for people at ongoing risk of exposure to rabies virus or other lyssaviruses. These include the following:
- People who work with live lyssaviruses in research laboratories should have VNAb (rabies virus neutralising antibody) titres measured every 6 months. If the titre is <0.5 IU per mL, they should receive a single intramuscular booster dose. People who are immunocompromised should have their VNAb titre measured 2–4 weeks after the booster dose. If the titre is <0.5 IU per mL, they should receive another booster dose. There is no need for serological testing after this additional dose. Laboratory staff at ongoing risk should continue to check their VNAb titres every 6 months.
- People with exposure to bats in Australia or overseas, or people who are likely to be exposed to potentially rabid terrestrial mammals overseas should have a single intramuscular booster dose 1 year after their 1st dose of rabies vaccine pre-exposure prophylaxis (or 1 year after their 1st dose of post-exposure prophylaxis if they had a category II or III exposure before receiving pre-exposure prophylaxis; see Table. Lyssavirus exposure categories). These people should have VNAb titres measured every 3 years after that. If their VNAb titre is <0.5 IU per mL, they should have a further single intramuscular booster dose. Alternatively, after the 1st booster dose, they can have a further single intramuscular booster dose every 3 years without determining the VNAb titre. An intramuscular booster dose of rabies vaccine should still provide adequate protection even if given more than 1 year after the 1st dose of pre-exposure prophylaxis.9,11
Always give booster doses of rabies vaccine by the intramuscular route. Never use the intradermal route to administer booster doses.
To determine whether a person should receive a booster dose of rabies vaccine because their VNAb titre falls below 0.5 IU per mL, consider:
- their anticipated risk of exposure — that is, whether they are routinely handling sick animals or rabies reservoir species in rabies-enzootic areas
- their health status, such as level of immunocompromise (see Table. Types of medical conditions and immunosuppressive therapy and associated levels of immunocompromise) or a history of poor vaccine response
- their timely access to vaccination for post-exposure prophylaxis if they are exposed
Figure. Booster algorithm for people at ongoing risk of exposure to rabies virus or other lyssaviruses
IU = international units; PEP = post-exposure prophylaxis; PrEP = pre-exposure prophylaxis
This flowchart helps to decide if people at ongoing occupational risk need booster doses of rabies vaccine.
For laboratory staff at risk, perform serological testing every 6 months.
For veterinary workers, people who handle bats or may need to handle bats, and people who have ongoing exposure to potentially rabid terrestrial mammals in rabies-enzootic countries, give a single intramuscular booster dose 1 year after pre-exposure prophylaxis. Then perform serological testing or give a booster dose every 3 years from receipt of the 1-year booster dose.
After serological testing, for those who have a virus neutralising antibody titre of at least 0.5 IU/mL, no further action is needed until either there is further exposure (then give post-exposure prophylaxis as per rabies or bat lyssavirus post-exposure algorithms, unless exposure occurs within 3 months of receiving complete post-exposure prophylaxis, when no immediate vaccination is required) or the next serological testing period elapses (then perform serology).
For those with a virus neutralising antibody titre of <0.5 IU/mL, give a single intramuscular booster dose for immunocompetent people. For immunocompromised people, give a single intramuscular booster dose then check serology after 2–4 weeks. If the antibody titre is <0.5 IU/mL, give another booster dose. If further exposure occurs, give post-exposure prophylaxis as per the terrestrial animal post-exposure algorithm or the bat post-exposure algorithm.