Prince Philip hasn't had flu "for 40 years".
Prince Philip
The 95-year-old prince joined his wife Queen Elizabeth on a tour of the Francis Crick Institute in London - a major biomedical research centre that aims to develop new ways of preventing, diagnosing and treating disease like cancer, HIV and malaria - and revealed his apparent immunity to the common viral infection.
Philip asked flu expert Dr. Yi Pu Lin if someone could develop immunity or resistance to flu, then said: "Why haven't I had flu for the last 40 years?"
Dr. Lin, who is the assistant director of the new institute's worldwide influenza centre, which helps determine the content of flu vaccines, later spoke of how it was entirely possible for the Duke of Edinburgh to have developed immunity to the bug.
She told reporters: "He said he was now 95 and he may previously been infected and now he has immunity, even with new viruses coming the immunity can be stimulated, so that's possible.
"Different people have different immuno responses and for some people it's probably easier to catch and for some people probably not that (easy)."
But she then explained it was possible Philip may have had a "sub-clinical infection", meaning his immune system was able to fight off the virus without him ever showing symptoms or feeling unwell.
She added: "You don't get symptoms but actually you've had a virus and your body's fought with it and overcome it, so you don't have problems and you don't know you've had flu."
She also told how environment is also a factor in people getting ill and so, unlike the public who "go to the Tube every day", Philip is less likely to encounter the virus in his daily life.
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