Nearly HALF of all Americans hospitalized due to COVID-19 may have mild cases or are asymptomatic, study suggests
- A new study looked at COVID-19 patients admitted to VA hospital across the country from March 2020 to June 2021
- Patients were considered 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 rose to 48% by June 2021, after the vaccines became widespread and the Delta variant became dominant
- Researchers say this means about half of patients are either mildly ill or were admitted for another reason and learned they had Covid after hospitalization
Nearly half of Americans who are hospitalized due to COVID-19 may have mild cases or may be asymptomatic, a new study suggests.
Researchers looked at patients admitted to medical canters within the healthcare system of the Department of Veterans Affairs (VA) since the start of the pandemic.
They found that before COVID-19 vaccines were widely available and the Delta variant was the dominant strain, 64 percent of hospitalized patients were considered moderately or severely ill.
However, after the vaccine rollout was well underway and Delta was dominant, the proportion of seriously ill patients fell to 52 percent.
The team, from VA Boston Healthcare System and Tufts University, in Medford Massachusetts, says this means a little less than half of patients currently in the hospital either have mild cases or were admitted for an entirely different reason and were then discovered to have COVID-19.
A new study found that, until early January 2021, 64% of hospitalized patients were moderately ill their oxygen saturation levels (SpO2) fell below 94%. This figure dropped to 52% by June 2021, after the vaccines became widespread and the Delta variant became dominant
Researchers say this means about half of the 96,000 patients hospitalized in the U.S. are either mildly ill or were 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 how well the U.S. is doing against COVID-19.
According to the Department of Health and Human Services, 96,870 virus patients are occupying hospital beds across the country, the highest figure seen since February 2021.
But researchers say the figure does not reveal how many in the hospital are severely ill and how many just happened to discover they have COVID-19 while hospitalized.
For the study, published on Monday on pre-print site Research Square, the team looked at patients admitted to VA hospitals between March 1, 2020 to June 30, 2021.
All patients were required to have a laboratory test confirmed COVID-19 infection either 14 days prior to admission or while they were admitted to the hospital.
Researchers defined moderate-to-severe Covid by looking at oxygen saturation levels (SpO2).
Normal oxygen levels are around 95 percent so patients were considered seriously ill when levels fell below 94 percent one day between one day before and two weeks after a positive test.
Oxygen levels that were higher were deemed as having either mild or asymptomatic illness.
Over the course of the study period, more than 47,000 Covid patients were examined at more than 100 VA hospitals across the U.S.
Results showed that from March 2020 to early January 2021 – before the COVID-19 vaccines were available to most Americans and before the Delta variant become dominant – 36 percent of patients had mild or asymptomatic cases.
However, this proportion grew after the shot rollout was expanded and the Delta strain made up most infections.
Between mid-January 2021 and June 2021, 48 percent of patients admitted to hospitals were either mildly ill or had visited hospitals for another reason and only found out they ere infected after being tested.
This means that potentially half of all hospitalized patients are not seriously ill with the disease.
The researchers say their study has limitations including that VA patients are not representative of the general population because most patients are male and no children were involved in the study.
But they did add that the data likely shows that vaccines are effective at preventing severe disease, that the Delta variant is more transmissible but not more dangerous and that hospitalization rates can be misleading.
‘The proportion of hospitalizations that are due to severe COVID-19 has changed with vaccine availability, thus, 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 straightforward and objective change that should improve the value of the metric for tracking SARS-CoV-2 disease burden.’