The study suggests that nearly HALF of all Americans currently hospitalized with COVID-19 may have mild cases or be asymptomatic.
- A new study examined COVID-19 patients admitted to VA hospital nationwide from March 2020 to June 2021
- Patients were considered to be moderately or severely ill if their oxygen saturation levels fell below 94%.
- Until early January 2021, 36% of patients had mild or asymptomatic cases
- This figure increased to 48% from mid-January 2021 to June 2021 after vaccines became widespread and the Delta variant became dominant.
- Researchers say this means that about half of currently hospitalized patients are slightly ill or have been admitted for another reason compared to last year.
A new study suggests that nearly half of Americans currently hospitalized for COVID-19 may have mild cases or be asymptomatic.
The researchers examined patients admitted to medical facilities of the Department of Veterans Affairs (VA) health system since the start of the pandemic.
They found that from March 2020 to early January 2021, before COVID-19 vaccines were widely available and the Delta variant was the dominant strain, 64% of hospitalized patients were considered moderately or severely ill.
However, after vaccine deployment was well underway and Delta was dominant, the proportion of seriously ill patients fell to 52%.
The team, from VA Boston Healthcare System and Tufts University in Medford Massachusetts, says this now means just under half of the patients in the hospital they had mild cases or were admitted for a completely different reason and were found to have COVID-19.
A new study found that by early January 2021, 64% of hospitalized patients were moderately ill and their oxygen saturation (SpO2) levels were down from 94%. This figure fell to 52% in June 2021, after vaccines became widespread and the Delta variant became dominant.
Researchers say this means that about half of the 96,000 patients hospitalized in the United States are slightly ill or admitted for another reason and learned they had Covid after hospitalization.
Public health experts have previously stated that hospitalizations are the metric that best defines U.S. performance against COVID-19.
According to the Department of Health and Human Services, 96,870 virus patients occupy hospital beds nationwide, the highest figure since February 2021.
But investigators say the figure does not reveal how many of the hospital are seriously ill and how many went on to find out they had COVID-19 while they were hospitalized.
For the study, published Monday in the Research Square prepress site, the team examined patients admitted to AV hospitals between March 1, 2020 and June 30, 2021.
All patients were required to undergo a laboratory test confirmed by COVID-19 infection 14 days prior to admission or while hospitalized.
The researchers defined Covid as moderate to severe by observing oxygen saturation (SpO2) levels.
Normal oxygen levels were around 95%, so patients were considered to be seriously ill when levels dropped from 94% one day between one day before and two weeks after a positive test.
Higher oxygen levels were considered to have mild or asymptomatic diseases.
Over the study period, more than 47,000 Covid patients were examined at more than 100 VA hospitals in the United States.
The results showed that from March 2020 to early January 2021, before COVID-19 vaccines were available to most Americans and before the Delta variant became dominant, 36% of patients had mild or asymptomatic cases.
However, this proportion grew after the shot was extended and the Delta strain constituted the majority of infections.
Between mid-January 2021 and June 2021, 48% of patients admitted to hospitals were slightly ill or had visited hospitals for another reason and only learned that they were infected after the test.
This means that potentially half of hospitalized patients are not seriously ill with the disease.
The researchers say their study has limitations, including that patients with VA are not representative of the general population, as most patients are men and no children participated.
But they added that the data probably show that vaccines are effective in preventing serious disease, that the Delta variant is more communicable but not more dangerous, and that hospitalization rates can be misleading.
“The proportion of hospitalizations due to severe COVID-19 has changed with vaccine availability, therefore, increasing proportions of mild and asymptomatic cases are included in hospitalization reporting metrics,” the authors wrote. .
“The addition of simple measures of disease severity to the case definition of a SARS-CoV-2 hospitalization is a direct and objective change that should improve the value of the metric for monitoring disease burden SARS-CoV-2 “.
