The CDC (Center for Disease Control) has just released a study of the seroprevelence of antibodies to SAR-CO-2 (COVID-19) in Six U.S. states, including Connecticut between March 23 and May 3, 2020.
The study estimated that these states had between 6 to 24 times the number of reported cases.
Commercial Laboratory Seroprevalence Survey Data
In Connecticut the seroprevelence (percentage of people in the population with antibodies) was estimated at 4.94%, which would mean the state at the beginning of May, had six times the number of reported cases.
New York City Metro region had the highest estimated seroprevelance at 6.93%, or 12 times the number of reported cases.
Missouri had a seroprevelence of only 2.65%, but this represents 24 times the number of reported cases.
The CDC will be conducting this study in additional states as well as retesting these areas.
South Florida, for instance, likely has a much higher seroprevelance now than when the study was taken in April.
The reason for the underreporting of cases, according to the authors, was likely "people may not have been counted because they had mild illness or no symptoms and did not get medical care or testing."
The authors emphasize that we still don’t know how long antibodies last or if they prevent someone from being reinfected.