VANCOUVER, British Columbia, Oct. 19 (UPI) — A third wave of H1N1 influenza among youth is unlikely, but older U.S. adults may be at greater risk of catching it this flu season, Canadian researchers say.
Dr. Danuta Skowronski of the British Columbia Centre for Disease Control and University of British Columbia and colleagues says compared blood levels of 1,127 people ages 9 months to 101 for H1N1 antibodies before and after the 2009 pandemic.
Before the pandemic, 10 percent of children and adults age 70 and under had protective levels of H1N1 antibodies, while 77 percent of those age 80 and older had protective levels.
However, after the fall 2009 immunization campaign, there was a 70 percent protection rate in people age 20 and under, 44 percent in those ages 20-49 and 30 percent in those ages 50-79, the researchers say. People ages 70-79 years had the lowest rate of antibodies — 21 percent — while those age 80 and older had higher rates.
“The higher percentage with seroprotection we observed in the young may have resulted from higher pandemic H1N1 infection rates and earlier prioritization of pandemic H1N1 vaccine to young children,” Skowronski says in a statement.
“Adults 50-79 years exhibited the lowest seroprotection and also remain at higher risk of severe outcomes if infected.”
The findings are published in the Canadian Medical Association Journal.
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