Polyvalent influenza vaccine information

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Polyvalent influenza vaccine is a type of influenza vaccine that provides immunity against more than one type of antigen.^[1] In the second week after receiving the flu shot, the body's immune system is triggered by the antigens so the body starts producing antibodies. These antibodies help fight against influenza viruses. Influenza symptoms and deaths can be prevented by getting an influenza vaccine every year.^[2] Currently circulating influenza strains that can cause seasonal epidemics include influenza A viruses, which can be further divided into subtype A(H1N1) and A(H3N2), and influenza B viruses.^[3]

Influenza viruses were first identified in 1933 when a group of scientists, Wilson Smith, P.P. Laidlaw, and C.H. Andrewes, discovered that there was no bacteria infection from the throat samples of patients infected by influenza. They concluded that a virus caused the disease. After that, the researchers Thomas Francis and Jonas Salk developed the first influenza vaccine at the University of Michigan. The vaccine was tested for safety and effectiveness in the United States Army. It was afterward licensed for use. However, researchers had suspected that there was more than one viral strain of influenza as some patients did not develop antibodies to the strain discovered in 1933. By undergoing many investigations, the researchers discovered the influenza B virus. Thus, the influenza B virus was added to the vaccines and packaged as a bivalent vaccine in 1942.^[4]

There are multiple types of polyvalent influenza vaccines available in the market, including egg-based, cell-based, and recombinant influenza vaccines. The World Health Organisation (WHO) will announce the viral strains to be included in flu vaccines annually. Starting from 2021/2022, all influenza vaccines are quadrivalent, containing two influenza A and two influenza B antigens.^[5] These are called quadrivalent influenza vaccines (QIVs). Vaccination may also cause a range of adverse effects on patients, from fever, injection site pain to anaphylaxis, which is a severe allergic reaction.