The coronavirus may be an even bigger problem than previously thought.
The Centers for Disease Control and Prevention published a new study that found that the numbers of COVID-19 cases in some areas of the US were more than 10 times higher than reported between March and May.
Based on antibody testing, places including New York and South Florida had drastically more coronavirus cases than were initially reported during the first wave, according to the paper, published in JAMA Internal Medicine on Tuesday.
More than 16,000 samples were collected from San Francisco, Connecticut, southern Florida, Louisiana, Minneapolis, Missouri, New York City, Philadelphia, Utah and western Washington. The number of people who tested positive for coronavirus antibodies — meaning they had the virus at one point — was much higher than the number of cases reported from the same time.
Limited testing availability during this period and the fact that many carriers of the virus can be asymptomatic may have contributed to the striking disparity, the researchers said.
“The findings may reflect the number of persons who had mild or no illness or who did not seek medical care or undergo testing but who still may have contributed to ongoing virus transmission in the population,” the study reads.
In Connecticut, where the lowest gap was found, infections were six times higher than the state reported. In Missouri, positive antibody tests were 23.8 times higher than actual reported cases — the highest discrepancy cited in the study.
Most other cities in the study had cases more than 10 times more than previously known.
Not all patients sought health care in the first wave, but the study suggests that in New York City, cases could have been 1,000 times greater than the 545 reported on March 16.
However, just because many more people carry COVID-19 antibodies than previously known does not mean most people are immune to the disease.
“At present, the relationship between detectable antibodies to [the coronavirus] and protective immunity against future infection is not known,” the study says.
However, early trials of a COVID-19 vaccine have sparked immune system responses: “These early results hold promise,” vaccine developer Sarah Gilbert told Reuters.