The researchers' analysis found a significant reduction in infectiousness, as defined by reductions in influenza illnesses in household contacts, when oseltamivir was used for treatment of ill persons, but not when zanamivir was administered. Although these results are of interest, the authors stress that the numbers were small and combined estimates from two studies for each drug were used in both instances. Furthermore, oseltamivir treatment of ill persons did not appear to reduce the frequency of influenza infection in their contacts.
In exploring the reasons for oseltamivir's greater effects on infectiousness, the authors speculated that the different modes of administration ?oral for oseltamivir and inhaled for zanamivir ?and resultant upper-respiratory viral levels could be the key, with zanamivir not reaching or affecting influenza virus in the nose. While both antivirals reduced cough, in earlier studies inhaled zanamivir did not significantly reduce nasal symptoms. In the paper the authors discussed the possibility that infectious droplets inhaled and exhaled from the nose may be important in viral transmission, thus orally administered oseltamivir might have an advantage in limiting spread.
In addressing the limitations to their research, the authors call for further stu
Source:Fred Hutchinson Cancer Research Center