The H5N1 bird flu virus has caused sporadic cases in humans
Luca Bruno/Associated Press/Alamy
If the H5N1 bird flu virus sparks a pandemic, the elderly may have better immunity than the young because of past exposure to related viruses.
Previous clusters of H5N1 cases included elderly people less chance of catching the virus than younger individuals, so the scientists hypothesized that the former group may have stronger immunity to the virus than younger individuals. This could be because older people have had more exposure to flu strains closely related to H5N1, called H1N1 and H2N2…
