Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. It is an occupational risk for employees of animal industries and is associated with contact with wildlife and domestic animals. Although Q fever infection may be asymptomatic, chronic sequelae such as endocarditis occur in 5% of symptomatic individuals. Disease outcomes may be predicted through measurement of immune correlates. Vaccination is the most efficient method to prevent Q fever. Currently, Q-VAX is the only licenced human vaccine. Q-VAX is highly effective" however, individuals previously exposed to C. burnetii are at risk of adverse reactions. This review examines the immunological responses of acute and chronic Q fever and the efforts to provide a safer and cost-effective Q fever vaccine.

Plain language summary: Q fever is a disease that is spread by some animals, such as sheep and cattle, to humans. Although most people will recover if they get Q fever, some become very ill. There is a vaccine for Q fever (Q-VAX), but it can cause a reaction when given to some people. Research is ongoing into how the human immune system reacts to the bacteria that causes Q fever. A small number of people who get Q fever will develop a prolonged disease that can be serious and affect the heart, which is why there is also research into developing new vaccines for this disease. This research will look at those parts of the germ that causes Q fever that can be used for a new vaccine.