A doctor in Brazil this week said that a lack of COVID-19 testing is keeping the country’s infant death toll artificially low.

The BBC reported that an estimated 1,300 babies have died due to the coronavirus, nearly twice that of official data from the Brazilian Health Ministry, which estimates that just over 500 babies have died.

Fatima Marinho, an epidemiologist and senior adviser to the nongovernmental organization Vital Strategies, shared her research with the news outlet. She said that a lack of testing is keeping the true count lower than it really is.

Marinho found that there were 10 times more deaths in kids due to unexplained acute respiratory syndrome than reported in previous years, the BBC reported. She estimated that the virus has killed 2,060 children under 9 years old between February 2020 and March 15, 2021, which includes 1,302 babies.

Conversely, the Brazilian Health Ministry estimated that 852 children under 9 years old have died, including 518 babies.

Marinho told the BBC that she’s seen a rise in a condition called multi-system inflammatory syndrome, a rare but serious condition that can cause inflammation of vital organs. The BBC noted that the condition doesn’t account for all of the deaths that have occurred.

A study of more than 1,700 children and teenagers led by researchers at the U.S. Centers for Disease Control and Prevention (CDC) found that the condition appeared between two to five weeks after initial infection.

Roughly 38 percent of patients who were newborns to age 4 experienced low blood pressure or shock, and 44 percent were admitted to intensive care.

Brazil has been one of the hardest hit countries of the coronavirus pandemic. The nation has logged more than 13.6 million coronavirus infections since the pandemic began, behind only India and the U.S., according to data from Johns Hopkins University.

The country has also reported more than 361,000 cumulative deaths, coming second only to the U.S.