One-third of Americans infected with coronavirus in 2020

August 26, 2021 – About a third of the American population had been infected with coronavirus 2 by the end of 2020, according to a new study published today in Nature.

Jeffrey Shaman, PhD, director of the Climate and Health program at Columbia University, and his colleagues simulated the spread of the coronavirus in 3,142 counties in the United States.

The United States recorded the highest number of confirmed COVID-19 cases and deaths in the world in 2020. More than 19.6 million cases were reported by the end of the year.

But the authors stress that “69% of the population remained sensitive to viral infection. “

“We have not taken the leap”

Jill Foster, MD, a pediatric infectious disease physician at the University of Minnesota School of Medicine, Minneapolis, says the study adds evidence that: “We haven’t made it past COVID-19 and we are far from being collective immunity – if it exists for SARS-CoV-2. “

She said the figures presented are of particular concern when it comes to the number of people who are susceptible and capable of actively infecting others: “Much higher than most people imagined and much higher than their comparison, flu. “There are even more sensitive people than we thought,” Foster added. “If the pattern continues where the Delta variant infects a significant portion of those vaccinated, the number of susceptible people is increasing even more than expected. “

Foster said the numbers represent a warning that COVID must be treated as an ongoing threat.

“We have to recognize that there is a COVID-19 infection simmering and erupting periodically across the country,” she said. “It is not monolithic and varies across geography and seasons in a way that is difficult to predict, except that at some point there are probably more infections present than we can identify and more people. susceptible to infection as we calculated. “

Decreased mortality rates

Some of the data showed good news, Shaman says. The death rate from infection fell from 0.77% in April to 0.31% in December. The authors suggest that this may be due to improvements in diagnosis and treatment, patient care, and reduced disease severity.

However, the death rate was still nearly four times higher than the estimated death rate for influenza (0.08%) and influenza in 2009. pandemic (0.076%), point out the authors.

Joe K. Gerald, MD, program director with public health policy and management at the University of Arizona at Tucson, says this study helps confirm that COVID-19 is much more deadly than the flu and that the intensity of the response was appropriate.

“We should be prepared to invest a lot more in COVID-19 mitigation than seasonal flu because it has much bigger consequences,” he said.

The numbers help to point out that testing needs to improve. “We didn’t have enough tests available and they weren’t easily accessible. For much of the year we were flying in the dark,” Gerald said.

The number of tests has increased this year, he admitted, but tests are still lagging behind.

“We just can’t miss so many infections or diagnoses and hope to take control,” he said.

The study also highlights the huge variation by state and even by county in infections and deaths, and that variation continues. Gerald noted that the numbers make it difficult for some regions to take on broader mandates, as the threat of COVID-19 looks very different where they are.

“We have to think about the regions, the number of susceptible people and the testing capacity,” he said. “States and even counties should be given some leeway to make important public health decisions, as local conditions are going to differ at different times.”