Acupuncture Continuing Education

Flu Vaccine Linked to Swine Flu (H1N1) Outbreaks

Seasonal flu vaccines have been linked to increased outbreaks of H1N1 (Swine Flu) in four different epidemiological studies. Serious questions have been raised concerning the biological interactions between influenza strains and vaccines. Patients who received the seasonal “flu shot” in 2008 and 2009 had a significant increase of developing H1N1. Both the seasonal flu and the pandemic H1N1 flu are due to strains of influenza virus and separate vaccinations are used to prevent each illness. These findings may impact recommendations by doctors and nurses for patients seeking medical information.

An initial inquiry began after investigators noticed that the majority of people with illnesses characterized by fever and coughing had received the seasonal flu vaccine. The investigation was initiated to explain this phenomenon and looked at people receiving seasonal flu shots (TIV) and their subsequent outbreaks of H1N1. Four separate epidemiological studies were launched to study the cause and means of this phenomenon. The studies revealed that TIV vaccines were effective in reducing seasonal flu outbreaks but increased a person’s chances of getting the swine flu (H1N1). All four studies showed that those who received the seasonal flu vaccine had approximately twice the chance of developing the H1N1 swine flu. The study included researchers from the British Columbia Center for Disease Control (BCCDC) in Vancouver, the National Microbiology Laboratory in Winnipeg, Canada; and the Ontario Agency for Health Protection and Promotion.

A study published in PLoS medicine in April 2010 revealed the unexpected findings from the four epidemiological findings. The trivalent inactivated influenza vaccine (TIV) was shown to have a counterproductive effect toward H1N1. Patients presenting with influenza syndromes were tested by a network of physicians for influenza virus with RT-PCR and an investigation of demographics, clinical outcomes, and vaccine status. Influenza-positive patients were then compared with influenza-negative patients. The results confirmed that TIV lowered the incidence of seasonal flu outbreaks when properly matched with circulating influenza strains in a given season. Alternately, mismatched vaccines did not have the same clinical benefits. However, even with adjustments for comorbidities, age, and geography; the seasonal flu vaccine (TIV) appeared as a risk factor for the swine flu for those under 50 years of age. The four studies conclude that recipients of the seasonal flu vaccine are approximately twice as likely to get the swine flu (H1N1). A causal link has not been established between TIV and H1N1 and investigators suggest further studies to explain this unexpected phenomenon. Both nurses and doctors will be better informed regarding patient recommendations once further study has been completed.