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, older people may have better immunity than younger people because of past exposure to closely related viruses.
In previous clusters of H5N1 cases, older people were less likely to catch the virus than younger individuals, so scientists hypothesised that the former group may have stronger immunity against the virus than those who are younger. This could be because older people have had more exposure to flu strains that are closely related to H5N1, called H1N1 and H2N2.…
