March 17, 2021 – Another 16 million Americans were infected with COVID-19 in the first 9 months of 2020 than previously reported, according to a new study.
Investigators rated 61,910 adults who said they were comfortable applying for life insurance. A total of 4,094, or 6.6%, had a positive coronavirus antibody test, which means they were previously infected with the virus.
The finding would “double the number of people infected with COVID-19 compared to the number of clinically diagnosed cases,” senior author Robert L. Stout, PhD, scientific director of the Clinical Reference Laboratory, Inc. in Lenexa, KS, told Medscape.
“As of September, the extent of the pandemic was about twice the number of reported cases,” added Stout. “It’s not like measles where it’s easy to identify. Quite simply, for the asymptomatic patient, they think everything is okay and continue their normal activities. Some practice recommended CDC guidelines in public places, others may not.” . “
The research letter was published online on March 16 in JAMA Network Open.
After investigators evaluated the national sample in September, they used that data to estimate the total number of total undiagnosed U.S. cases based on census data.
Compare gender, age, and state
The cross-sectional study included age, gender, country of residence, and antibody status. The average age of the study participants was 39 years. Of the 4094 positive cases, 54% were men.
The infection rate was slightly higher in women (6.9%) than in men (6.4%).
The lowest infection rate in asymptomatic people over 70 was 2.8%. In contrast, the youngest cohort up to the age of 30 had the highest rate at 9.8%.
Infection rates varied greatly by state, “said Dr. Stout and co-author Steven Rigatti of MassMutual.
The highest rate in September was 14.4% in New York, followed by 12% in Louisiana and 10% in Nevada. The states with the lowest rates included Oregon at 1.5%, Maine at 0.6%, and Alaska at 0%.
Implications and Skepticism
“Our estimate implied more than double the number of infections than cases reported to the Centers for Disease Control and Prevention,” the researchers note, “suggesting a more widespread pandemic.”
Possible limitations of the study are the self-reporting on health – all people said they were comfortable – and the evaluation of the blood tests submitted using a random sample of the general population.
“Overall, the results are difficult to interpret because the sample for the study is a sample of people applying for life insurance,” said Dr. Neeraj Sood to Medscape.
The numbers could even be higher. “People applying for life insurance tend to be better educated, richer and likely to be more risk averse. So the results of this study do not apply to the general population and are likely to represent a lower limit of actual seroprevalence in the general population,” he said Sood, director of the COVID initiative at the Schaeffer Center at the University of Southern California in Los Angeles.
Sood was the lead author of a JAMAresearch letter published in May that assessed the infection rate among adults in Los Angeles County.
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