The trivalent live oral poliomyelitis vaccine (OPV) is a vaccination that provides immunity against three strains of the poliovirus: types 1, 2, and 3. It is administered orally and contains live, weakened forms of the virus. The vaccine is primarily used to prevent poliomyelitis, a highly contagious viral infection that affects the nervous system and can lead to paralysis, muscle weakness, and even death.
The trivalent live OPV works by stimulating the body's immune response to produce antibodies against the poliovirus. When administered orally, the weakened viruses replicate in the intestines, triggering the immune system to recognize and attack the poliovirus. This response creates immunity, protecting the vaccinated individual from future poliovirus infection.
The trivalent live OPV has been widely used in global polio eradication efforts due to its efficacy, ease of administration, and ability to provide immunity not just to the vaccinated individuals but also to those who come into contact with them. It plays a crucial role in interrupting poliovirus transmission, particularly in areas with active polio outbreaks.
Despite its effectiveness, the vaccine carries a small risk of causing vaccine-associated paralytic poliomyelitis (VAPP) in very rare cases. For this reason, some countries have switched to the use of inactivated polio vaccine (IPV), which contains killed poliovirus and poses a lower risk of VAPP. However, the trivalent live OPV remains an essential tool in the fight against polio, especially in regions where the disease is still endemic.
