Masked train passengers in Mexico City during 2009 Swine Flu outbreak (credit: Eneas De Troya, source: Wikimedia Commons)
Around 1 in 5 of the population were infected in both recent outbreaks of seasonal flu and the 2009 H1N1 influenza pandemic, but just 23% of these infections caused symptoms, and only 17% of people were ill enough to consult their doctor, according to new UCL-led research. These findings come from a major new community-based study comparing the burden and severity of seasonal and pandemic influenza in England over 5 years, published in The Lancet Respiratory Medicine journal. "Reported cases of influenza represent the tip of a large clinical and subclinical iceberg that is mainly invisible to national surveillance systems that only record cases seeking medical attention", explains lead author Dr Andrew Hayward (UCL Infection & Population Health). "Most people don't go to the doctor when they have flu. Even when they do consult they are often not recognised as having influenza. Surveillance based on patients who consult greatly underestimates the number of community cases, which in turn can lead to overestimates of the proportion of cases who end up in hospital or die. Information on the community burden is therefore critical to inform future control and prevention programmes." The Flu Watch study tracked five successive cohorts of households across England over six influenza seasons between 2006 and 2011.
TO READ THIS ARTICLE, CREATE YOUR ACCOUNT
And extend your reading, free of charge and with no commitment.
