In healthy individuals, the first encounter with a virus leads
to a primary antibody response. When an infection occurs with
the same or a similar virus, a rapid antibody response occurs
that is called the secondary antibody response. Antibodies are
critical for preventing many viral infections, including
influenza. But reinfection may occur if we encounter the same
virus before the primary response is complete. Recently three
cases of confirmed infection with 2009 influenza H1N1 were
reported in Chile. The first patient had laboratory confirmed
infection; treatment with oseltamivir resolved symptoms after 48
hours. Twenty days later the patient developed a second bout of
laboratory confirmed influenza which was treated with
amantadine. The second patient acquired laboratory confirmed
influenza in hospital, was treated with oseltamivir and
recovered. Two weeks later, while still in hospital, the patient
had a new episode of laboratory confirmed influenza infection.
Treatment with oseltamivir again resolved th