COVID-19 vaccines: Can they be mixed and matched?

Here are some of the many questions readers have sent us that we’ve put to health and science experts. Have your own pandemic question? Send it to chicagotribune.com/ask. Get the latest Chicago COVID-19 information and updates from Chicago Tribune reporters and editors on our COVID19 Facebook page.

Can you mix and match vaccines?

Some people might be wondering if they have an adverse reaction to a vaccine for a first shot, if they can follow up with a different vaccine for a second dose.

Dr. Michael Lin, an infectious disease specialist at Rush University Medical Center, said the mRNA vaccines were not studied in a “mix and match” fashion, so patients should make a strong effort to receive the same product.

“That said, in exceptional situations, any available mRNA vaccine could be used as a second dose with a minimum interval of 28 days, and that would be considered a complete vaccination, even if potentially mismatched,” he said.

Guidance from the Centers for Disease Control and Prevention notes that if someone has received one dose of an mRNA vaccine, like the Moderna or Pfizer vaccines, the same brand should be administered for the second dose.

But, the agency added, in situations where the first dose was received but the patient cannot complete the series with the same vaccine, “consideration may be given to vaccination with Janssen COVID-19 Vaccine (Johnson & Johnson) at a minimum interval of 28 days from the mRNA COVID-19 vaccine dose.” This should be done under the supervision of a health care provider experienced in managing severe allergic reactions.

The agency noted that in only “exceptional situations,” any available mRNA vaccine may be administered at a minimum of 28 days between doses to complete a vaccination series. The agency also noted it is better to delay the second dose up to six weeks to receive the same product than to receive a mixed series.

How might anesthesia interact with the vaccine? Can you plan surgery after having COVID-1 9 or a recent vaccination?

According to the American Society of Anesthesiologists, there is no evidence that either COVID-1 9 or the vaccine interferes with anesthesia. However, the group noted in a statement, because surgery is stressful on the body and can temporarily strain your immune system, “You should wait until you are fully recovered from COVID-1 9 or you are fully immunized after vaccination before proceeding with surgery.”

As for either essential or elective surgery after contracting COVID-19, the group recommends waiting four weeks if you had no symptoms or only mild ones and 12 weeks if admitted to intensive care. If vaccinated, surgery should be scheduled at least two weeks after the final dose.