According to the latest data, the CDC estimates that around 20 million Americans were infected with COVID-19 in 2020, but an astonishing study suggests the number could be much higher than previous estimates.

The recent article published in Nature offers a more comprehensive estimate that places the true number of infections by the end of 2020 at more than 100 million people. That’s equal to almost one third of the U.S. population. This revised number shows just how rapidly the novel coronavirus spread through the country last year.

If this estimate is accurate, it is safe to assume that the more transmissible delta variant which became dominant this year, may have already infected around 100 million more Americans in 2021.

This would mean that almost 75% of the population already have a natural immunity to the virus, not counting those who were vaccinated. The numbers would also mean that the overall infection fatality rate is far lower than previously believed.