By the end of 2020, 103 million Americans (31 percent) or about a third of the US population were infected by SARS-COV-2. Socked University of Columbia came to this conclusion. This means that less than a quarter of infections (22 percent) falls confirmed in public health reports based on testing from COVID-19. This is reported in an article published in the journal Nature.
Researchers simulated the transmission of SARS-COV-2 in all 3142 US districts and between them, using population data, mobility and confirmed cases. In some parts of the country, the infection has gained more distribution. According to scientists, by the end of 2020, in the areas of the Upper Middle West and the Mississippi Valley, including the states of Dakota, Minnesota, Wisconsin and Iowa, more than 60 percent of the population were infected. 48 percent of Chicago residents were also infected, 52 percent of Los Angeles, 42 percent Miami, 44 percent of New York and 27 percent of the inhabitants of Phoenix.
Testing revealed the growing number of infections, but did not give a true picture. The proportion of confirmed cases reflected in the estimates of researchers increased from 11 percent in March to 25 percent in December, which reflects the improvement of testing capabilities. Nevertheless, the level of detection remained significantly below 100 percent. The overwhelming majority of infectious diseases are not explained by the number of confirmed cases.
The mortality rate decreased due to increased treatment and public health measures. The share of infected who died from COVID-19 fell from 0.8 percent during the spring wave to 0.3 percent by the end of the year.