A randomised controlled trial of the immunogenicity and safety of a formaldehyde-inactivated Coxiella burnetii vaccine in 8-week-old goats.

Coxiella burnetii causes Q fever in individuals exposed to infected ruminants. Vaccination in 3-4-month-old goats, has been reported to result in significantly greater reduction in C. burnetii shedding compared to goats vaccinated one month before breeding, the most commonly used strategy of controlling Q fever on infected intensively-managed herds. It is possible that an even greater reduction in the number of animals shedding C. burnetii could be achieved if vaccination were administered shortly after protection from colostrum antibodies wanes and animals become susceptible to infection with C. burnetii. This study aimed to evaluate the immunogenicity and safety of a formaldehyde-inactivated phase 1 C. burnetii vaccine in 8-week-old goats. Two injections, four weeks apart, elicited specific IgM and IgG responses in all vaccinated goats (n = 6), while no antibodies were detected in two control groups (n = 12). Swelling at the site of inoculation was observed in all the vaccinated and in 10/11 of the placebo-treated goats but receded after 3 weeks. Weight change and rectal temperatures were also comparable between vaccinated and control goats. The data indicated that this vaccine could be suitable for immunising 8-week-old goats, although further trials to determine level of protection against challenge are required.