What does it mean, the fact that the swine flu outbreak is occurring in the Spring (Northern Hemisphere)?

Spring is not the typical flu season. Experts are trying to understand what that will mean with respect to the spread of the swine flu. Will we be in fact saved by Summer Weather? Here are some expert opinions.

Felice J. Freyer,  Medical Writer, Providence Journal: “Then there’s the weather. The flu spreads more readily in cold, dry air, apparently because the droplets from coughs and sneezes become lighter and stay airborne longer. Cold seasons are also when people are more likely to huddle together. Just sitting four feet away from someone instead of side by side makes a significant difference in one’s likelihood of getting infected, Gravenstein said.  The arrival of warm, humid summertime weather could quiet this swine flu, at least for a time. The 1918 pandemic started with a small springtime outbreak before exploding the following autumn. Today, governments and communities will be preparing for that possibility. Indeed, a lull between spring and fall might be just enough time to develop a vaccine. ”

Dr. Craig Bowron, MinnPost: “Is summer on our side? It’s still not clear how virulent this strain is, and how far it will go geographically and chronologically. But the epidemiology of influenza suggests that we have summer on our side. “The big question here is whether this virus is going to behave like influenza viruses usually do. That is to say, sort of disappear along about April or May, and not resurface until November, December, or January,” Rhame said.  We’re able to dismantle a virus into individual gene sequences, but we still don’t understand why influenza is a winter disease.  “There are a lot of hypotheses about that, but no real understanding,” Rhame told me. Are there any leading guesses? “The density of people; air exchange rates – when your windows are open the air in your house turns over faster; weather things like humidity – those are some ideas, but no one really knows.” Still, the timing of this current outbreak makes Rhame a bit nervous. “It’s been informally reported in the Mexican epidemiology that they saw an increased number of cases in April, so that’s not the tail-off of cases that you usually see in March, April, May,” he explained. “If this swine influenza virus has got a shoulder, that’s cause for concern. You’d really like to see it winding down. If it’s winding up, that’s something to worry about; it might mean that somehow, contrary to all influenza behavior in the past, it’s not going to disappear in the summer. I sure would like to see some indication that it is tailing off.”

World Meteorological Organization (WMO), United Nations, is more cautious: “The influence of meteorological and climate conditions in the transmission patterns of swine influenza and its possible seasonality are as yet not adequately understood and are the subject of ongoing research. The World Meteorological Organization (WMO) works on aspects of weather, climate and health with the World Health Organization (WHO). While there are some indications that influenza epidemics may be associated with weather conditions, non-climatic factors, including virus type, existing levels of immunity in the population and human behaviour are generally considered to be more closely related to epidemics.”

Photo from The Sydney Morning Herald.