| Version | Summary | Created by | Modification | Content Size | Created at | Operation |
|---|---|---|---|---|---|---|
| 1 | Dean Liu | -- | 1946 | 2022-10-11 01:43:19 |
Type A influenza vaccine is for the prevention of infection of influenza A virus and also the influenza-related complications. Different monovalent type A influenza vaccines have been developed for different subtypes of influenza A virus including H1N1 and H5N1. Both intramuscular injection or intranasal spray are available on market. Unlike the seasonal influenza vaccines which are used annually, they are usually used during the outbreak of certain strand of subtypes of influenza A. Common adverse effects includes injection site reaction and local tenderness. Incidences of headache and myalgia were also reported with H1N1 whereas cases of fever has also been demonstrated with H5N1 vaccines. It is stated that immunosuppressant therapies would reduce the therapeutic effects of vaccines and that people with egg allergy should go for the egg-free preparations. There are different methods in developing the vaccines. Traditionally, inactivated viral vaccine and live attenuated virus vaccine have been approved. Inactivated viral vaccine is primary used parentally and the live attenuated vaccine is used intranasally. Development of new technologies including the recombinant hemagglutinin technology have widely been studied. Influenza A virus was successfully identified and isolated by Wilson Smith, Christopher Andrewes, and Patrick Laidlaw in the 1930s and the first inactivated monovalent influenza A vaccine was made after a decade. The first H5N1 vaccine was approved in 2007. It was intentionally developed to prepare for the possible H5N1 outbreak in the future. Moreover, in view of the H1N1 outbreak in 2009, H1N1 monovalent vaccines, targeting only H1N1 virus, was produced. Influenza A exists in many subtypes including H5N1, H1N1 and H3N2. Different formulations of monovalent vaccines have been developed over the years to cater different needs and antigens identified.