The yellow fever vaccine is a live attenuated vaccine that stimulates the immune system to produce a protective response against the yellow fever virus. The vaccine contains a weakened but still live strain of the virus that cannot cause disease in healthy individuals but can still stimulate the immune system.
The mechanism of action of the yellow fever vaccine involves the activation of both innate and adaptive immune responses. The virus in the vaccine enters host cells and replicates, leading to the production of viral antigens that are presented to the immune system. This triggers the activation of innate immune cells, such as macrophages and dendritic cells, and adaptive immune cells, such as T and B lymphocytes.
The vaccine produces neutralizing antibodies that can prevent infection with the wild-type virus. It also activates cellular immune responses, including T-cell responses, that can control and clear viral infections.
The spectrum of activity of the yellow fever vaccine is broad, as it protects against the yellow fever virus, a flavivirus transmitted by mosquitoes. The vaccine is effective against all known virus strains and can provide lifelong immunity in most individuals. The vaccine is recommended for individuals who live in or travel to areas where yellow fever is endemic or where outbreaks have occurred.
