The mortality risk for patients who recovered from severe COVID-19 infections is twice as high the year following their illness as those who haven't been infected, a new study from the University of Florida shows.

Researchers' findings appear in the journal Frontiers in Medicine.

"These findings reinforce that the internal trauma of being sick enough to be hospitalized with COVID-19 has a big consequence for people's health. This is a huge complication of COVID-19 that has not been shown before," said Arch G. Mainous III, the study's lead investigator and a professor in the department of health services research, management and policy at the UF College of Public Health and Health Professions.

UF Health researchers had previously discovered people who had been hospitalized with severe cases of COVID-19 were more than twice as likely to require another hospitalization for health problems brought on by COVID-19 when compared to people who had mild infections that didn't require hospitalization.

Florida hospitals this summer treated a record number of patients with COVID-19 as the delta variant swept across the state, most of whom were not vaccinated.

"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," Mainous said in the statement. "COVID-19 is even more devastating than we thought when only focusing on the initial episode. The downstream risk for the most severe outcome, death, is definitely high enough to hopefully make everyone rethink the impact of COVID-19."

The findings could be problematic as the omicron variant was first discovered in South Africa and is now in more than 25 countries, including the United States.

Moderna CEO Stéphane Bancel predicted Tuesday that the existing COVID-19 vaccines are likely to be less effective against the emerging variant.