H infl uenzae is one of the common causative agents of
pneumonia and, therefore, these data suggest that virus
infection can lead to secondary bacterial infections and
potentially pneumonia. The patients with COPD in this
study104 were inhaled corticosteroid-naive and, therefore,
the eff ects of inhaled corticosteroids on virus infection
and secondary bacterial infection in patients with COPD
are unknown. Virus infections can impair host immunity
to bacterial infection through multiple mechanisms104,106
and in an animal model, mice infected with infl uenza
and treated with dexamethasone had higher bacterial
loads after subsequent infection with Listeria
monocytogenes.107 Whether similar mechanisms occur in
human beings or with other viruses and bacterial species
is not known. Because both bacterial and virus infections
are common in COPD, studies of the eff ects of inhaled
corticosteroids on virus—bacvirus—bacteria interactions in human
beings are urgently needed.