The researchers noted that Brazil is currently suffering a “deadly surge” of COVID-19 infections, which has been attributed to the spread of a new strain known as P.1 (B.22.214.171.124).
They examined public COVID-19 data from the southern Brazilian state of Parana—the largest state in the southern half of the country—which has seen a total of 553,518 positive cases from September 2020 through March 17.
Their report, published on medRxiv on April 2 ahead of peer review, found that the proportion of patients who died either held steady or declined between September and January. However, starting February, fatality rates rose for almost all groups over age 20.
From January to February, these rates tripled among COVID-19 patients aged 20 to 29, from 0.04 percent to 0.13 percent, and doubled among those aged 30 to 39, 40 to 49, and 50 to 59.
“Individuals between 20 and 29 years of age whose diagnosis was made in February 2021 had an over three-fold higher risk of death compared to those diagnosed in January 2021,” the researchers said.
“Taken together, these preliminary findings suggest significant increases in case fatality rates in young and middle-aged adults after identification of a novel SARS-CoV-2 strain circulating in Brazil, and this should raise public health alarms.”
It’s unclear what is driving the growing infection rate among Brazil’s younger population. Medical professionals have suggested that limited vaccines and the P.1 variant that first emerged in the city of Manaus late last year, coupled with the UK variant, have contributed to the rise.
Government data shows that last month, more than 2,030 Brazilians aged 30 to 39 died from COVID-19, the disease caused by the CCP (Chinese Communist Party) virus. That’s roughly double the number recorded in January. Of those in their 40s, there were approximately 4,150 fatalities in March, compared to 1,823 deaths in January. For those aged between 20 and 29, fatalities spiked from 242 to 505.
Local doctors also told CNN last week that young Brazilians are getting sicker after being infected with COVID-19 than during previous waves of the pandemic.
The P.1 strain features mutations associated with higher viral infectivity and greater resistance to antibodies—though experts caution that more study is needed to verify the “fitness” of the mutant virus.
“Last year, we had more critical elderly patients. Now it’s completely distinct. We’re dealing with a substantial number of severe patients in their 30s to 50s,” Dr. Anne Menezes from Manaus’s Getulio Vargas Hospital told Al Jazeera.
Reuters contributed to this report.