When a doctor gives a vaccination, usually the advice is to take an over the counter pain medication to relieve the pain, fever and discomfort that occurs after the vaccination. But some new research from the University of Rochester indicates that might not be the best advice.

Dr. Richard Phipps, a research scientist, looked at the behavior of the enzyme cyclo-oxygenase 2 in laboratory cultures of cells. Human immune cells produce cyclo-oxygenase 2 when they're stimulated, and the enzyme helps to cause fever and inflammation.

According to Doctor Phipps, it turns out the cyclo-oxygenase 2 might also be key in making the antibodies we're hoping to have created when we get a vaccine. "We've also studied mice that completely lack this enzyme and in studies where we vaccinate mice," he says, "we've found that those mice that lack this cyclo-oxygenase 2 enzyme, in fact, make much lower levels of antibody."

Phipps says that's where pain medication can come in. Many people take a non-steroidal anti-inflammatory drug such as ibuprofen to block production of cyclo-oxygenase 2 and counteract those uncomfortable effects of fever and inflammation. "So the implications are if you were taking these drugs and were vaccinated, you would likely make less antibodies than you would if you were not on the drugs."

Phipps believes there are many questions that still need to be answered about this interaction. He wonders, for example, if there might be times after a vaccination when a non-steroidal anti-inflammatory drug might do more damage than others. He says this might make vaccines even less effective in people who already have poorly functioning immune systems, such as the elderly or people with AIDS.

Phipps says this could have implications for the vaccine supply, especially in the case of shortages. "It may be that much lower doses of vaccines in general could be given to humans if it were not for the fact that many people take these non-steroidal anti inflammatory drugs."

The next step, Phipps says, is to conduct a human study in which volunteers are given a vaccine and then a pain reliever drug and scientists monitor the amount of antibodies they make in response. The study appeared in this month's Journal of Immunology.