A pair of new studies suggests that statins may have a detrimental effect on the immune response to influenza vaccine and its effectiveness at preventing serious illness in older adults.
The findings, if confirmed by additional research, may have implications for flu vaccine recommendations and guidelines for statin use around the time of vaccination.
“Apparently, statins interfere with the response to influenza vaccine and lower the immune response”
In one of the studies, researchers analysed immune response data from an earlier flu vaccine trial conducted during the 2009-10 and 2010-11 flu seasons.
The first study, funded by Novartis Vaccines – which also sponsored the original trial – focused on the potential effect of statin use on patients’ initial immune responses after being immunised.
The analysis drew on data about nearly 7,000 adults over 65 in four countries.
The researchers found statin users had a significantly reduced immune response to vaccination compared to those not taking statins, as measured by the level of antibodies to the vaccine strains in blood three weeks after immunisation.
The effect was most dramatic in patients on synthetic statins, rather than naturally derived statins, said the researchers.
If confirmed by other research, the findings could support the preferential use of high-dose flu vaccine or vaccines containing adjuvants to boost immune response in older patients, in an attempt to counteract the apparent effect, the study authors said in the Journal of Infectious Diseases.
Lead study author Dr Steven Black, from Cincinnati Children’s Hospital Medical Center, said: “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.”
“Their findings are far from conclusive and merely point to a possible issue that needs further research”
In the other new study Emory University researchers investigated the possible impact of statin therapy on the effectiveness of flu vaccine at preventing serious respiratory illness.
The researchers analysed data spanning nine flu seasons from 2002-11, including information about flu vaccination, statin prescriptions, and cases of medically attended, acute respiratory illness among nearly 140,000 people.
After adjusting for various factors, the researchers observed that vaccine effectiveness for preventing serious respiratory illness was lower among patients taking statins compared to patients who were not on statins, particularly when flu was widespread in the state.
The study authors noted that their findings have potential implications for guidelines regarding statin use in older adults around the time of vaccination, but additional studies, including research examining laboratory-confirmed cases of flu, are needed first.
Lead study author Saad Omer said: “What we found was a potential signal that the effectiveness of flu vaccine in older people may be compromised somewhat if they are on statins, compared to those who are not on statins.”
Commenting on the findings, British Heart Foundation medical director Professor Peter Weissberg said: “These two studies suggest that some types of statins may reduce the effectiveness of standard influenza vaccination.
“However, as the researchers point out, their findings are far from conclusive and merely point to a possible issue that needs further research,” he said.
“It is important that patients with heart disease should be vaccinated against flu and continue to take all of their medication,” he added.