ADVANCES IN FLU VACCINE TECHNOLOGY

Abstract

Unfortunately, every year, approximately 3 to 5 million people get severe influenza illness, and, in 290 000 to 650 000, influenza respiratory deaths occur (Kumar et al., 2018). Influenza virus is an acute upper respiratory tract virus infection in mammals and birds that targets the epithelial cells of the respiratory tract. However, it is primarily responsible for the yearly epidemic of seasonal flu. Influenza viruses are RNA viruses belonging to the Orthomyxoviridae family, including types A, B, and C. Influenza A virus (IAV) and B viruses cause moderate-to-severe respiratory illness outbreaks that affect hundreds of thousands of people yearly worldwide and can lead complications that result in 3–5 million hospitalizations globally (Palese, 2006). They can also cause viral pneumonia. The emergence of IAV dyspnea has been reported to result in high mortality rates (more than 50%), especially in immunocompromised patients. IAV is classified into different subtypes depending on the type of glycoproteins expressed on the surface of the viral envelope.

The major glycoproteins are hemagglutinin (HA), which allows the virus to attach to the host cell, and neuraminidase (NA), which cleaves the sialic acids on the cell surface to release newly synthesized progeny viruses. Influenza viruses are divided into two antigenically distinct groups or lineages: type A and type B. Interestingly, type C influenza viruses are similar in size and morphology to type A and B viruses but induce a milder manifestation of disease and are not responsible for the annual epidemics. The area and national collaborating centers screen and analyze HA solicitations from the respective secretions from atypical cases to identify new variants. The egg inoculating technique established in the 1960s for vaccine production has various limitations and is very coarse for better identification of new strains. The recommendation for the annual vaccination is updated three months before the vaccine's global distribution. This period will not readily allow for any newly emerged strains. A better and rapid vaccine production system is required and should be based on the advanced scientific technologies developed after the basic molecular biology of influenza C viruses, formulated in synthetic vectors that can easily allow for the detection of new variants. In addition, a strategy that can identify and characterize a patient- derived newly emerged virus is needed for the vaccine development process.