Background : |
Influenza B virus is the only species in the genus Betainfluenzavirus in the virus family Orthomyxoviridae. Influenza B virus is only known to infect humans and seals and this is believed to account for the lack of associated influenza pandemics in contrast with those caused by the morphologically similar influenza A virus, although both mutate by both antigenic drift and reassortment. However, it is thought that Influenza B virus could cause significant morbidity and mortality worldwide, particularly in adolescents and schoolchildren. WHO convenes technical consultations in February and September each year to recommend viruses for inclusion in influenza vaccines for the northern and southern hemisphere influenza seasons, respectively. Flu vaccines are based on predicting which mutants of H1N1, H3N2, H1N2, and influenza B will proliferate in the next season. Separate vaccines are developed for the Northern and Southern Hemispheres in preparation for their annual epidemics. One influenza A (H1N1), one influenza A (H3N2), and one or two influenza B viruses (depending on the vaccine) are included in each season's influenza vaccines (CDC, 2019). WHO has identified four strains as the most likely to circulate in the 2020-2021 influenza season, including Influenza A [A/swine/Shandong/1207/2016] virus. Since December, 2019, coronavirus disease 2019 (COVID-19) has been an international public health emergency and co-infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory viruses have been reported, complicating their diagnosis (Azekawa et al., 2020; Cuadrado-Payán et al., 2020; Wu et al., 2020). |