More than 41,000 Americans underwent an organ transplant in 2021, a new record and a 6% increase from 2020, when the pandemic caused a slight slowdown of the life-saving procedures.

Why it matters: There are more transplant patients than ever, and they are particularly vulnerable to the worst effects of COVID because of their compromised immune systems — although vaccines provide important protection.

Context: After transplants, patients must take immunosuppressive medications so their body doesn't reject their new organ.

• Since the drugs weaken their immune systems, transplant patients are more susceptible to catching infections that others would normally fight off, and this coronavirus is no different.

The state of play: Death rates among transplant patients who get COVID and need to be hospitalized are "very high," according to several studies — especially for lung transplant recipients.

• However, older age and chronic health conditions also put transplant patients at higher risk, just like they do for people who haven't gotten a transplant.

The big picture: Taking immunosuppressive drugs often reduces how effective vaccines can be, but studies in the U.S. and the U.K. show COVID vaccines drastically lower the risk of hospitalization and death for transplant patients compared with the unvaccinated.

Yes, but: Vaccinated transplant patients are still significantly more likely to get infected, become hospitalized or die from COVID than vaccinated people with fully functioning immune systems.

• That's why the CDC recommends the immunocompromised get "three mRNA doses and a booster."
• Transplant centers like the University of California San Francisco also want vaccinated transplant patients to "assume that you are not protected against severe disease after vaccination" and continue "wearing a mask, social distancing and encouraging your family and household members to get vaccinated."

The bottom line: "The risk of severe disease will always be higher in immunosuppressed patients, even if [COVID] becomes milder with Omicron," said Deepali Kumar, a transplant physician in Toronto and president-elect of the American Society of Transplantation. But "the unvaccinated remain at a huge disadvantage."