Painkillers may threaten power of vaccines

With flu-shot season in full swing and widespread anticipation of the HPV vaccine to prevent cervical cancer, a new University of Rochester study suggests that using common painkillers around the time of vaccination might not be a good idea.

Researchers showed that certain nonsteroidal anti-inflammatory drugs (NSAIDs), also known as cyclooxygenase inhibitors, react with the immune system in such a way that might reduce the effectiveness of vaccines.

The research has widespread implications: study authors report that an estimated 50 to 70 percent of Americans use NSAIDs for relief from pain and inflammation, even though NSAIDs blunt the body’s natural response to infection and may prolong it.

“For years we have known that elderly people are poor responders to the influenza vaccine and vaccines in general,” said principal investigator Richard P. Phipps, Ph.D., a professor of Environmental Medicine, and of Microbiology and Immunology, Oncology and Pediatrics. “And we also know that elderly people tend to be heavy users of inhibitors of cyclooxygenase such as Advil, aspirin, or Celebrex. This study could help explain the immune response problem.”

The study is available online in the Dec. 1, 2006, Journal of Immunology, and was funded in part by the National Institutes of Health. (See full study at: http://www.jimmunol.org/cgi/content/full/177/11/7811)

When a person is vaccinated, the goal is to produce as many antibodies as possible to effectively neutralize the infection. To do this, white blood cells called B-lymphocytes, or B cells, spring into action to produce those antibodies. B cells also serve as the immune system’s memory for future protection against the illness.

But Phipps and colleagues discovered that human B cells also highly express the cyclooxygenase-2 (cox-2) enzyme, which is not intrinsically bad unless it is overproduced, causing pain and fever. So, when a person takes a drug to block the cox-2 enzyme – and thereby reduce pain and fever – the drug also reduces the ability of B cells to make antibodies.

“The next step is to figure out the worst time to take drugs that inhibit cox-2 in the context of getting vaccinated. Is it the day before, the day of, or the day after" The timing is likely to be very important,” Phipps said. “But meanwhile, we believe that when you reach for the medicine cabinet to reduce pain at the injection site, that is probably the wrong thing to do.”