The way the currently available vaccines work is that they expose a person’s body to a small protein from the coronavirus that induces the immune system to start fighting the virus, as if the person had been fully infected, explains Adam Berman, M.D., an emergency medicine physician and associate chair of the emergency department at Long Island Jewish Medical Center in New York. The hope is that if your body learns to fight the coronavirus when you aren’t infected, then later, if you are, it will be able to protect you by fighting off the infection extremely quickly.
Essentially, the vaccine makes a beeline for your immune system, and “the vast, vast majority of medications that patients take do not affect their immune systems,” says Berman.
For example, the statin you take to guard against high cholesterol interrupts your cholesterol production and has nothing to do with your immune system, says William Schaffner, M.D., an epidemiologist and professor of preventive medicine and health policy at Vanderbilt University. Blood thinners like Warfarin or Eliquis work on your body’s blood clotting mechanism. Medicines to control diabetes, like Metformin, work on your glucose metabolism — again, nothing to do with your immune system.
Some medicines may dampen vaccine effectiveness
As with most rules of medical science, there are some exceptions. If you happen to be taking prescription drugs that do affect your immune system, the vaccine might not be as effective as it would be if you weren’t.
So if you have had an organ transplant and are taking immunosuppressant drugs or taking those drugs to treat an autoimmune disease, or if you’re taking certain cancer chemotherapies, the “immunosuppressive drug could decrease the efficacy of the vaccine,” says William Moss, M.D., executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health. Same goes for people who are HIV positive and take one or more medications that affect their immune systems.
Even so, Schaffner emphasizes, such medications will continue to work on the conditions you’re taking them for — and so will the COVID-19 vaccine.
“Should you still get the vaccines?” asks Schaffner, referring to the currently available COVID-19 vaccines from Pfizer-BioNTech and Moderna. “Absolutely. Now, can we guarantee that you will have 95 percent protection? No, but you will get some degree of protection. And some is better than nothing.”
Moss suggests that people think of the COVID vaccines in much the same way they do their annual flu shot or a shingles or pneumonia vaccine. The COVID vaccine “is a new type of vaccine, but fundamentally, it’s just a vaccine. It is like other vaccines that basically affect our immune system. And there’s no reason to have concerns about how that might interact with other medicines.”