The daily total of patients who acquired COVID-19 while in the hospital hit a record of about 4,700 in January — when omicron peaked — according to an analysis of federal data from The Wall Street Journal.
This figure peaked at about 1,100 patients during the delta wave, and reached 2,050 during the peak of the pandemic's first winter surge in 2020.
Thomas Tsai, MD, a public health researcher at Cambridge, Mass.-based Harvard University, who helped the Journal review HHS data, said the proportion of patients with hospital-acquired COVID-19 as a share of all non-coronavirus patients closely aligns with case numbers in their surrounding communities. The data indicates the overall percentage of patients who contract COVID-19 in the hospital doubles on days when surges reach their highs compared to days when cases are at low points.
In New York, for example, hospitals reported a daily peak of 620 patients in January, or 2.2 percent of total non-coronavirus caseload, who caught COVID-19 while there, coinciding with a time when communitywide cases were high.
Despite all the precautionary measures hospitals take, such as routinely screening patients and screening staff, "the hospital itself is not an island," Dr. Tsai told the Journal, adding that when there is a surge, there is a high chance that people with undetected infections will bring the virus inside hospitals, making it hard to keep track. "That's where the fire skips the fire line," he said.
An analysis of COVID-19 hospitalizations at four U.S. healthcare systems from March 20 to Aug. 21 put incidental admissions around 26 percent.
HHS stopped collecting and disclosing data on the number of patients who developed COVID-19 while in the hospital in mid-2020.
It has since published daily statewide totals for the total number of patients without the virus and those who caught it while admitted. Not all hospitals are required to report both figures every day, which makes it difficult for researchers to calculate the totals.
Researchers said the data is likely an undercount, in part because facilities don't have to report patients testing positive after less than two weeks while admitted or after being discharged.