TAMPA, Fla. (WFLA) — People who have recovered from severe COVID-19 are more than twice as likely to die within the year following their illness compared to those who have not been infected, according to a study from the University of Florida.

The study highlights serious effects the body can experience after severe infection, like cardiovascular, respiratory and clotting problems, often doubling their chances of rehospitalization and death.

“This is a huge complication of COVID-19 that has not been shown before,” the study’s lead investigator, Arch G. Mainous III, Ph.D. said.

Interestingly, researchers found that patients younger than 65 who recovered from severe COVID-19 had a greater chance of dying than their counterparts aged over 65 years or older.

“Our findings suggest the need for closer follow-up of patients who have been hospitalized with COVID in the same way we keep a close eye on people who are at risk for heart attack.”

The UF team analyzed data from 13,638 adult patient electronic health records who were tested for COVID-19 using a PCR, test. The researchers then followed patients for 12 months.

Moving forward, Mainous says preventing severe COVID-19 should be a primary focus. Researchers and health experts stress that vaccination is the most effective way to decrease the risk of hospitalization and death from COVID-19.