Do you have the Flu? Some may not Show Symptoms

Feeling a bit off but can't quite put your finger on it? A recent study shows that for some flu sufferers, they may have developed an infection without even experiencing any symptoms. In fact, according to lead study author Dr. Andrew Hayward, this could be true for 23 percent of flu cases. 

"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," he said, via a press release.

"Most people don't go to the doctor when they have flu," he added. "Even when they do consult they are often not recognized 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."

As researchers from the University College London in the United Kingdom studied data from The Flu Watch, they found that only 17 percent of infected people felt that they were ill enough to go to the doctor. 

To study the flu and its symptoms, researchers tracked 5 consecutive cohorts of households during the six flu seasons between 2006 and 2011 in England. All participants were required to provide blood samples before and after each flu season, annually. If participants showed any symptoms--including sore throat, fever, chills, etc.--Dr. Hayward and his team asked them to submit a nasal swab via the second day that the symptoms were discovered. 

Researchers found that 18 percent of the unvaccinated individuals had the flu during the 2009 pandemic, while 77 percent of them didn't show any symptoms at all. 

More information regarding the study can be found via The Lancet Respiratory Medicine Journal.