The actual number of people infected with the new coronavirus (Covid-19) in the United States was 2 to 13 times higher than the official number in the spring, the Centre for Disease Control and Prevention (CDC) showed on Tuesday.
The CDC tested blood from blood banks in 10 areas of the United States between March and June for coronavirus antibodies, which indicate that a person had previously come into contact with the virus.
These serological studies are conducted in many countries and allow researchers and health authorities to know the progress of the virus in the population, regardless of the availability of screening tests.
The CDC found that between 1 and 5.8% of people in the 10 tested areas were infected during this period, with the exception of New York, where prevalence reached 23.2% of the population as of 6 May, or one in four New Yorkers.
Compared to the official number of cases recorded on those dates, the actual number of infections was twice as high in Utah, ten times higher in South Florida in late April and up to 13 times higher in Missouri in late May. Even in New York, which was the US epidemic’s epicentre in the spring, there were ten times more people infected than the official number of cases.
The United States faced a shortage of tests in the spring, which contributed to underestimating the circulation of the virus and mortality, and experts say the country still is not testing enough.
The conclusion is twofold: on the one hand, hundreds of thousands of Americans unknowingly have the coronavirus and contribute to its spread; on the other hand, with usually about 5% of the population infected, the country was still far from the threshold of herd immunity at the end of spring.
The Brussels Times