WASHINGTON: The number of early Covid-19 cases in the US. USA It may have been more than 80 times higher, and probably doubled almost twice as fast as originally believed, according to a study saying the count may be due to testing problems, and the prevalence of asymptomatic individuals.
In the study, published in the journal Science Translational Medicine, scientists estimated the detection rate of symptomatic cases of Covid-19 using surveillance data for influenza-like illness (ILI) from the Centers for Disease Control and Prevention. Diseases (CDC) over a three week period in March 2020.
“We analyzed ILI cases from each state to estimate the number that could not be attributed to influenza and exceeded seasonal reference levels,” said Justin Silverman, co-author of the Pennsylvania State University study in the U.S.
“When you subtract this, you’re left with what we call excess ILI: cases that cannot be explained by influenza or the typical seasonal variation of respiratory pathogens,” Silverman explained.
The study noted that excess ILI showed an almost perfect correlation with the spread of Covid-19 across the country.
“This suggests that the ILI data is capturing cases of Covid, and there appears to be a much larger undiagnosed population than originally thought,” Silverman said.
According to scientists, the size of the observed increase in excess ILI corresponds to more than 8.7 million new cases during the last three weeks of March, compared to the approximately 1,00,000 cases that were officially reported during the same time period.
“We found that deaths in the US had doubled every three days and that our estimate of the infection rate was consistent with a doubling of three days since the first case observed in Washington state was reported. on January 15, “Silverman said.
Using this process, the scientists estimated infection rates for each state, noting that states that show higher infection rates per capita also had higher per capita rates of an increase in excess ILI.
Their calculation showed rates much higher than those initially reported, but closer to those found once states began completing antibody tests.
Citing an example, researchers said that at least 9 percent of the entire New York population was infected in late March.
After the state conducted antibody tests on 3,000 residents, they found an infection rate of 13.9 percent, or 2.7 million New Yorkers, the scientists added.
They said excess ILI may have peaked in mid-March, as fewer patients with mild symptoms sought care, and states implemented interventions that led to lower transmission rates.
Almost half of the states of EE. USA They had orders to stay home March 28, the study noted.
The findings, the researchers say, suggest an alternative way of thinking about the Covid-19 pandemic.
“Our results suggest that the overwhelming effects of Covid-19 may have less to do with the lethality of the virus and more to do with how quickly it initially spread through communities,” Silverman explained.
“A lower mortality rate coupled with a higher prevalence of disease and a rapidly growing regional epidemic provides an alternative explanation for the large number of hospital deaths and overcrowding that we have seen in certain areas of the world,” he added.
In the study, published in the journal Science Translational Medicine, scientists estimated the detection rate of symptomatic cases of Covid-19 using surveillance data for influenza-like illness (ILI) from the Centers for Disease Control and Prevention. Diseases (CDC) over a three week period in March 2020.
“We analyzed ILI cases from each state to estimate the number that could not be attributed to influenza and exceeded seasonal reference levels,” said Justin Silverman, co-author of the Pennsylvania State University study in the U.S.
“When you subtract this, you’re left with what we call excess ILI: cases that cannot be explained by influenza or the typical seasonal variation of respiratory pathogens,” Silverman explained.
The study noted that excess ILI showed an almost perfect correlation with the spread of Covid-19 across the country.
“This suggests that the ILI data is capturing cases of Covid, and there appears to be a much larger undiagnosed population than originally thought,” Silverman said.
According to scientists, the size of the observed increase in excess ILI corresponds to more than 8.7 million new cases during the last three weeks of March, compared to the approximately 1,00,000 cases that were officially reported during the same time period.
“We found that deaths in the US had doubled every three days and that our estimate of the infection rate was consistent with a doubling of three days since the first case observed in Washington state was reported. on January 15, “Silverman said.
Using this process, the scientists estimated infection rates for each state, noting that states that show higher infection rates per capita also had higher per capita rates of an increase in excess ILI.
Their calculation showed rates much higher than those initially reported, but closer to those found once states began completing antibody tests.
Citing an example, researchers said that at least 9 percent of the entire New York population was infected in late March.
After the state conducted antibody tests on 3,000 residents, they found an infection rate of 13.9 percent, or 2.7 million New Yorkers, the scientists added.
They said excess ILI may have peaked in mid-March, as fewer patients with mild symptoms sought care, and states implemented interventions that led to lower transmission rates.
Almost half of the states of EE. USA They had orders to stay home March 28, the study noted.
The findings, the researchers say, suggest an alternative way of thinking about the Covid-19 pandemic.
“Our results suggest that the overwhelming effects of Covid-19 may have less to do with the lethality of the virus and more to do with how quickly it initially spread through communities,” Silverman explained.
“A lower mortality rate coupled with a higher prevalence of disease and a rapidly growing regional epidemic provides an alternative explanation for the large number of hospital deaths and overcrowding that we have seen in certain areas of the world,” he added.
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