The four new studies conducted by Canadian researchers conclude that the traditional seasonal flu vaccine seems to have boosted the risk of infection with pandemic H1N1 swine flu by almost double.

In one study, the researchers revealed to use ongoing sentinel monitoring system in order to assess the frequency of prior vaccination with the seasonal flu vaccine in people suffering from H1N1 swine flu in 2009 compared to people without swine flu.

The study discovered that seasonal flu vaccination was linked with a 68 percent boosted risk of falling in prey to swine flu.

"I do think that they did the best they could with the data they had", said Dr. Mark Loeb, an infectious diseases expert at McMaster University in Hamilton who was not part of the study and who seems to be sceptical about the study’s conclusion.

The studies, published April 6 in the online journal PLoS Medicine, attributed to the combined of over 40 researchers including many of Canada's top influenza experts. The data is reported to be fetched from four studies that draw cases from British Columbia, Alberta, Ontario and Quebec.

However, the studies failed to show the presence of a true cause-and-effect link between seasonal flu vaccination and subsequent swine flu illness, or it is due to presence of a common factor among the people in the study.