U.S. health officials are monitoring an unusual situation in the United Kingdom, where COVID-19 cases and hospitalizations are simultaneously climbing due to the BA.2 subvariant, CNN reports.
COVID-19 cases were up 52 percent in the U.K. last week compared with the week prior, and hospitalizations were up 18 percent over the same period, according to the UK Coronavirus Dashboard. Cases reported March 11 (72,898) make up about one-third of what the U.K. recorded during its omicron peak in January, but cases are rising as fast as they were falling two weeks earlier, when the country lifted pandemic-related restrictions.
The seemingly in-tandem ascent of cases and hospitalizations is unusual, given that increases in COVID-19 cases preceded increases in hospitalizations by about 10 days to two weeks in previous waves.
"So we're obviously keenly interested in what's going on with that," Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, told CNN.
Dr. Fauci said in conversation with his U.K. counterparts, they attribute the rising cases and hospitalizations to three things, listed in order of contribution: the BA.2 variant, which is more transmissible than the original omicron; the opening of society, with people socializing indoors without masks; and waning immunity from vaccination or prior infection.
Hospitalizations in the U.K. raise questions, given that BA.2 doesn't appear to cause more severe disease.
"The issue with hospitalization is a little bit more puzzling, because although the hospitalizations are going up, it is very clear their use of ICU beds has not increased," Dr. Fauci said. "So are the numbers of hospitalizations a real reflection of COVID cases, or is there a difficulty deciphering between people coming into the hospital with COVID or because of COVID?"
BA.2 makes up a small portion of COVID-19 cases in the U.S. but has been growing steadily, according to outbreak.info, a platform that tracks data on COVID-19 variants and is supported by the CDC and other national research groups. The seven-day rolling average of percent of BA.2-positive sequences in the U.S. was 17 percent as of March 7, the latest date for which data is available. By comparison, the seven-day rolling average of percent of BA.2-positive sequences in the U.K. was 78 percent as of March 10, the latest date for which data is available.