From the Guidelines
A booster dose of rabies vaccination can be taken after initial vaccination when the serum titer falls below a certain threshold, typically every 2 years for those in the frequent-risk category, or immediately if exposed again after a previous complete vaccination series. The timing of the booster dose depends on the individual's exposure risk category, with those in the continuous risk category requiring more frequent serum testing and potential booster doses every 6 months 1. Key factors to consider when determining the need for a booster dose include:
- The individual's occupation and exposure risk, such as laboratory workers, veterinarians, and animal-control officers
- The frequency of potential exposures, with those in high-risk categories requiring more frequent serum testing and booster doses
- The results of serum testing, with booster doses administered if the titer falls below a certain threshold For individuals who have completed a full pre-exposure vaccination series and are then exposed to rabies, a booster dose is typically recommended on days 0 and 3 after exposure, along with proper wound care 1. It is essential to consult with a healthcare provider to determine the best course of action based on individual circumstances and exposure risk. In general, the goal of booster doses is to maintain a serum titer that corresponds to a value of at least complete neutralization at a 1:5 serum dilution by the RFFIT, as recommended by the Advisory Committee on Immunization Practices 1.
From the Research
Booster Dose Timing
The timing of a booster dose of rabies vaccination after initial vaccination can vary depending on several factors, including the type of vaccine used, the individual's risk of exposure, and their immune response.
- According to a study published in 2007 2, the first rabies booster vaccination is recommended to be given one year after the primary course, with subsequent boosters given every three to five years thereafter.
- A study from 1998 3 found that a booster injection at 1 year provides long-term seroconversion, and that antibody titers 2 weeks after the 1-year booster can predict long-term immunity.
- Another study from 1999 4 reported that a four-site intradermal booster regimen with cell-culture rabies vaccine on day 0 is associated with a significantly higher antibody response than the conventional booster regimen.
- More recent studies, such as one from 2023 5, suggest that a serology test should be performed 1 year after pre-exposure prophylaxis, followed by a first booster if required, and that the interval between subsequent serology tests and the first booster dose should be no longer than 3 years.
- A 2020 study 6 found that routine administration of a single booster dose of purified vero-cell rabies vaccine 1 year after the primary series could be considered, but more evidence is needed to support the benefit in terms of immunity and logistics.
Factors Influencing Booster Dose Timing
Several factors can influence the timing of a booster dose, including:
- The type of vaccine used, with different vaccines having different immunogenicity profiles 3, 4
- The individual's risk of exposure, with those at higher risk requiring more frequent boosters 2, 5
- The individual's immune response, with those having a weaker response requiring more frequent boosters 3, 6
- The time elapsed since primary immunization, with antibody levels decreasing over time 6