Infection with influenza virus results in acquisition of immunity, preventing reinfection with the homologous virus. Although reinfection following primary infection is rare, its incidence depends on immunity of human body, antigenic diversity of influenza virus, and the presence of outbreak in the community. During the pandemic influenza (H1N1 2009), a child and two women were reinfected by H1N1 influenza virus several weeks after the primary infection, and they were successfully treated again by oseltamivir. This case series will provide additional information on diagnosis, treatment, and prevention of the pandemic influenza (H1N1 2009).
Antigenic Variation ; Child ; Female ; Human Body ; Humans ; Incidence ; Influenza, Human ; Orthomyxoviridae ; Oseltamivir ; Pandemics ; Viruses