An international team affirmed that adults can suffer from flu once every five years. But many people will feel sick more often than that, but as per the researchers other flu-like infections are to be blamed.

The researchers have based their findings on a field study conducted in China. In the research, the scientists took and tested blood samples of 151 volunteers aged between seven and 81. Main aim of testing the blood samples was to know how often flu infections take place.

Experts affirmed that the data would help experts to know more about the risk of infection and also, the spread area of the disease through communities. In the study published in the journal PLoS Biology, the researchers looked at nine main strains of flu known to present in the world between 1968 and 2009.

The researchers from the Imperial College London and institutes in the US and China checked the presence of antibodies in the blood samples. The test unveiled whether or not the participants have been infected with the viruses and how often.

The results unveiled that the children suffered flu on average every other year, but fly infections became less frequent with age. When the person is of 30 years and onwards then flu infections tended to take place at a steady rate of about two per decade.

Study's senior author Dr Steven Riley from the Medical Research Council Centre for Outbreak Analysis and Modelling at Imperial affirmed, "The exact frequency of infection will vary depending on background levels of flu and vaccination".

Dr. Riley said that from the study findings, they came to know that influenza infections are actually quite less common than considered. In childhood and adolescence, the infections are more common and it might be because children mix more frequently with other people.