A perfect storm of factors related to the swine flu pandemic have many experts predicting the usual seasonal flu viruses will be no-shows this season. First off, the rush for H1N1 vaccinations saw many patients being vaccinated for the seasonal varieties as well. And then there’s “crowding out,” a little-understand phenomenon that means novel flu strains essentially monopolize patients' lungs.
Virtually all flu cases in Europe and the US this season have been H1N1, and the outbreak in South America earlier this year did not see significant levels of either of the two main seasonal viruses. “I would bet against a seasonal flu this year,” one professor of epidemiology tells Bloomberg. “But I wouldn’t bet very much money.”