WASHINGTON, Oct. 29 (UPI) -- Two new studies question whether the flu vaccine is less effective for older people taking statins to control cholesterol, raising concern about the vaccine's ability to prevent flu and serious respiratory illness.
About 40 percent of the United States' population over the age of 65 is prescribed statins, which have a known negative effect on the immune system. The drugs have had a significant effect at preventing cardiovascular events by lowering cholesterol in patients.
While the results of the two studies, both of which are published in the Journal of Infectious Diseases, show decreasing effectiveness of flu vaccine in patients being treated with statins and are cause for concern, researchers do not suggest a change in treatment for anybody.
"Instead, the results of these studies should be viewed as hypothesis-generating and should prompt further investigations into whether statins reduce inactivated influenza vaccine immunogenicity and, if so, the mechanisms by which immune responses and associated vaccine effectiveness are adversely affected," wrote the authors of a commentary published in the Journal of Infectious Diseases with the two studies.
A study on the influence of statins on flu vaccine in elderly patients focused on about 7,000 adults over age 65.
The analysis showed that, three weeks after being vaccinated, people on statins had significantly fewer level of antibodies in their blood for flu strains targeted by the vaccine than people not using statins. The effect, researchers wrote, was most dramatic in people taking synthetic, rather than naturally-derived, statins.
The second study looked at the effect of statins on flu vaccine being able to prevent serious respiratory illness older people, based on data collected by a Georgia-based managed care company on 140,000 people between 2002 and 2011.
Patients on statins were found in the study to be more susceptible to respiratory illnesses, though researchers note not all illnesses are caused by flu, so further studies will be needed with lab-confirmed flu strains.
"Apparently, statins interfere with the response to influenza vaccine and lower the immune response, and this would seem to also result in a lower effectiveness of influenza vaccines," said Dr. Steven Black, a researcher at Cincinnati Children's Hospital Medical Center, in a press release.
Although a stronger, high-dose version of the flu vaccine exists, it has not been approved for use in the United States.