Study: H1N1 Vaccine Only Effective for 2 Years
According to a recent study, those who are administered the H1N1 flu vaccine lose their immunity to the virus within 2 years, not 10 years, as previous research suggested.
Using data from 138 countries compiled in FluNet, a database created by the World Health Organization, researchers mapped the spread of various flu strains between 2006 and 2015. They found that H1N1 spread throughout Europe and Eastern Asia in a “skip and resurgence,” meaning that the virus, although expected to reappear in 2011-2012, never materialized.
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“Fundamental epidemiological theory explains this pattern: after the first waves of infection, the population built up immunity and the virus could not explode. But immunity wore off after a couple of years, so enough people were once again susceptible in 2013.”
While researchers noticed the “skip and resurgence pattern” throughout Europe and Eastern Asia, North America did not have a skip year.
They noted that the high incidence rate in the United States could be due to the vaccination against the major seasonal influenza strain, H3N2. If the vaccine slowed the spread of H3N2, it could have decreased competition with the H1N1 virus, allowing it to flourish.
“Vaccination is still the most efficient way to protect humans against the flu. But if the viruses included in the seasonal flu vaccine do not match well against that year’s dominant flu strains, it will reduce effectiveness of vaccination, and infections will surge dramatically,” said Daihai HE, PhD, lead author of the study and assistant professor in the department of applied mathematics at The Hong Kong Polytechnic University.
“More in-depth study on the impact of vaccination policy, more accurate prediction of future dominant strains and the design of better vaccinations is urgently needed,” he concluded.
-Michelle Canales Butcher
Reference:
The Hong Kong Polytechnic University. Immunity from H1N1 flu vaccine wears off rapidly. October 29, 2015. www.researchsea.com/html/article.php/aid/9182/cid/3/research/medicine/the_hong_kong_polytechnic_university/immunity_from_h1n1_flu_vaccine_wears_off_rapidly.html. Accessed November 5, 2015.