According to the British Medical Journal, flu vaccines may not be as effective as the hype. Worldwide public policy recommends the use of inactivated influenza vaccines (vaccines that contain dead viruses) to prevent seasonal outbreaks. But because influenza viruses change and the number doing the rounds varies from year to year, it's difficult for scientists to study the precise effects and effectiveness of vaccines.Most studies are of poor quality (especially with the elderly population) and show evidence of bias. There is also surprisingly little evidence on the safety of flu vaccines. (Science Daily)
