A new study suggests it’s not just you who might be immune to the flu pandemic.
The new study, published online by the journal PLOS ONE, found that people with a history of infection and a history that included more than 10 symptoms may be more susceptible to catching the virus.
The study was conducted by researchers from the Johns Hopkins Bloomberg School of Public Health and the University of California, Berkeley.
The study is the first to look at whether a history or a history alone of illness increases the risk of getting the flu.
“It is possible that this relationship between history and illness can persist even when there is a flu pandemics history,” the study’s lead author, Dr. Joseph T. Miller, a professor of epidemiology at Johns Hopkins, said in a statement.
“This suggests that the flu might be transmitted to people through the history of an illness or even through a single symptom.”
The study examined data from the National Health and Nutrition Examination Survey, a nationally representative sample of about 4.2 million Americans, which was collected in 2012.
More than 2.6 million people, or 6 percent, of the sample reported a history with at least one flu-like illness.
The rest of the population did not report a history, or a single flu-related symptom.
The researchers found that those with at-risk histories of illness were more likely to have been exposed to influenza-related symptoms.
The majority of those who had a history had a single or multiple symptoms that were more severe than those they didn’t.
Miller said it was possible that having a history would have made them more susceptible.
“People with more history might have been more susceptible,” he said.
“People who are exposed to a greater number of flu-associated symptoms might be more likely not to be susceptible.”
The researchers also found that a history was not a prerequisite for getting the virus, as long as the person had been infected before the start of the pandemic and had been vaccinated.
In fact, the researchers found it was more common for people who had at least 10 symptoms to have already been infected by the time they were contacted.
The people with history had lower immune function, which could lead to higher levels of antibodies to the virus circulating in the body.
People with a previous history of influenza illness also had lower levels of immunity.
In other words, the people with histories were more vulnerable to getting the pandemias virus because they had already been exposed, the study found.
Miller said this suggests that having past exposure to flu symptoms could increase the risk for getting infected by infecting someone else with the pandems virus.
“There is a high risk of infection by someone else that comes from having a prior history of flu illness,” he told ABC News.
The findings are interesting and important, he said, but it’s important to recognize that it is a hypothesis and that further research is needed.
“The real challenge for this is to understand the mechanisms and why people develop immunity,” Miller said.
For more health news, visit ABCNews.com.