‘Stealth’ Omicron Subvariant Is Likely Behind A Surge In Cases And Hospitalizations In The U.K.

Topline

Coronavirus infections and hospital admissions are surging across the U.K. just weeks after restrictions were lifted and testing scaled back as part of government plans for “living with Covid,” a concerning uptick experts say could be driven by behavioral changes, waning immunity and the rise of the more infectious BA.2 omicron relative.

Covid cases increased across the UK last week.

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Key Facts

Last week, around one in 13 people tested positive for coronavirus in Scotland, one in 18 in Northern Ireland, one in 25 in England and one in 30 in Wales, according to data from the Office of National Statistics infection survey, which randomly tests a sample of the population for the virus.

The figures mark an increase in the proportion of people testing positive for Covid-19 across all countries of the U.K. compared to the week before, the ONS said, and government data also shows the number of Covid patients in hospitals across the U.K. is increasing, reaching the highest point in over a year in Scotland.

Experts told Forbes it’s difficult to offer a precise explanation for why cases and hospital admissions are increasing at the moment or whether this foreshadows a greater wave.

Professor Liam Smeeth, Director of the London School of Hygiene & Tropical Medicine, told Forbes the increase in cases is to be “expected” given the behavioral changes and increased socializing after the U.K. lifted all pandemic restrictions, including the requirement to self-isolate if testing positive for the virus (a few measures do remain in Wales and Scotland).

It’s “certainly plausible” that waning immunity from booster shots could explain the increase, Professor Paul Hunter, an infectious disease expert at the University of East Anglia, told Forbes, especially as cases rose first among older people who would have received them earlier, but the fact that recent data shows an increase in all age groups indicates fading protection is “probably not a major contribution.”

Hunter said the “main driver” of the increase is the BA.2 omicron subvariant, a more transmissible virus relative of omicron that has been increasing since the beginning of the year and became dominant around two weeks ago.

Crucial Quote

“In my estimation the most important driver of the recent increase in cases and hospitalizations in the U.K. is the rise of BA.2 omicron subvariant,” Professor Mark Woolhouse, an epidemiologist at the University of Edinburgh, told Forbes. Given that cases of the original BA.1 omicron are falling, Woolhoouse said waning immunity or behavioral changes were unlikely to be “the main drivers” behind the increase, and BA.2 appears to be able to evade immunity from vaccines and prior infection.

What We Don’t Know

The size of a new Covid wave. As we do not yet know “how many people will prove susceptible to it [BA.2]… it is impossible to predict the size of any wave,” Woolhouse said. “There is no obvious reason why cases should fall dramatically in the next few weeks – Covid-19 is still here and still a significant public health problem.”

Surprising Fact

That hospital admissions are rising in the U.K. now. Hunter told Forbes that while it’s relatively unsurprising the number of infections are increasing as restrictions are eased and an infectious variant becomes the dominant form of the virus, the current increase in hospital admissions is unexpected. “Admissions normally lag seven to 10 days behind changes in case rates,” he explained. There are several potential explanations for the rise, Hunter said, including BA.2 omicron possibly causing more severe disease than other forms of omicron, problems in data collection and reporting, an increase in older and more vulnerable people at greater risk of hospital admission or more people being admitted to hospital with, but not for, Covid. The answer, as well as an idea of how severe it may get, should become clearer as more data becomes available, Hunter said.

What To Watch For

A rise in U.S. cases and hospitalizations. Trends in the U.K. and Europe tend to foreshadow trends elsewhere. For the U.S., patterns of infections and hospital admissions have been broadly similar to those in the U.K. but lagged a few weeks or months behind. The proportion of BA.2 is also on the rise, accounting for an estimated 12% of cases, according to the CDC. Unlike the U.K., however, the U.S. has relatively low levels of vaccine uptake and even fewer people have received booster shots, while many people received theirs months ago. This could leave it less well prepared to weather another wave than the U.K. Smeeth, commenting on just the British situation, said the country has “strong population immunity” through infections and vaccination. Covid vaccines are “life-savers” but “not total transmission stoppers.” Smeeth recommended continued caution and having fourth doses “as soon as possible” when they are made available.