You probably remember that swine flu caused a lot of worry in the medical community last year. Although last year’s outbreak was relatively mild compared to other epidemics, experts were predicting that there would likely be a future wave of the flu that will hit again in the fall and possibly be much more virulent.
Well, here’s some good news on the flu front — that second wave of H1N1 never really hit and now researchers are saying they don’t expect this year’s flu season to reach epidemic proportions.
A research team in British Columbia, Canada, examined the results of blood tests given to 1,127 people in the province both before and after the 2009 pandemic. Before the pandemic, less than 10% of children showed signs of antibodies, which help the immune system develop resistance to specific germs. By contrast, more than three-quarters of people over the age of 80 had the antibodies, suggesting they’d been exposed to the virus before.
Researchers determined last fall that the current H1N1 virus was a distant genetic cousin of the more virulent H1N1 “Spanish flu” virus of 1918. That flu epidemic was devastating, causing more than 30 million deaths worldwide, with 500,000 in the United States alone. The Spanish flu virus circulated throughout the United States for almost 40 years until it was replaced in 1957 by the H2N2 “Asian flu” pandemic virus. The Asian flu caused 70,000 deaths in the United States.
In 1977, there was another strain of H1N1 called the “Russian flu,” but researchers found that people exposed to H1N1 before 1957 were largely immune to the Asian flu virus. This has led to speculation that older people may have developed antibodies against the current strain of H1N1 as well. And, in fact, this latest study bears that conclusion out.
After the 2009 pandemic, the B.C research team found that 70% of people under the age of 20 showed signs of antibody protection. They suggest that the higher percentage of antibodies in blood observed in younger patients may have resulted from higher pandemic H1N1 infection rates and earlier prioritization of pandemic H1N1 vaccine to young children. Once again, the vaccine will be available this winter for those who wish to get immunized.
Is there anyone that should worry about the upcoming flu season? The researchers caution that adults 50 to 79 years showed the lowest antibody protection. This age group, the research team says, is at higher risk of severe outcomes if infected. They urge that the findings from this study support a shift from the prioritized immunization of the young that occurred in fall 2009 to prioritized immunization of older adults for the coming 2010-2011 influenza season.
Now — to reiterate the positive findings of the study: you can feel reassured about the reduced likelihood of a third pandemic H1N1 wave during the 2010-2011 season.