H2N2 virus

The H2N2 virus was the cause of the 1957 flu pandemic, which began in East Asia and spread globally. This was the second major influenza pandemic of the 20th century, following the 1918 pandemic and preceding the 1968 pandemic. The 1957 outbreak resulted in an estimated one to two million deaths worldwide, making it the least severe of the three 20th-century influenza pandemics.

The H2N2 virus is a reassortant strain, meaning it originated from a mix of avian and human influenza viruses. Over time, it underwent genetic modifications known as antigenic drift, leading to periodic epidemics. After about a decade, the H2N2 virus disappeared, replaced by the H3N2 subtype, which caused the 1968 pandemic. A vaccine was developed against the H2N2 virus, and antibiotics helped treat secondary infections, limiting the pandemic's spread and mortality.12