Key Takeaways:

• Covid-19 infections in England have reached their highest level since the epidemic began in March, according to a new study.
• The Imperial College researchers raised concern that it may become more difficult to detect growing differences as the government cuts testing.

According to a new study, Covid-19 infections in England reached their greatest level since the pandemic began in March, driven by the omicron subvariant BA.2 and declining immunity among older persons.

According to the React-1 study led by Imperial College London, the total Covid prevalence rate more than quadrupled last month from February, when infection rates were declining after the omicron-driven January peak. 

Since then, the introduction of BA.2, a more transmissible variant of omicron, has expedited new infections and established itself as the dominant strain in England, accounting for over 90% of positive samples.

Despite increasing immunization levels among the population, higher infection rates may lead to an increase in hospitalizations, according to Paul Elliott, head of the React program and chair in Epidemiology and Public Health Medicine at Imperial College London.

Covid-19 rates are rising among adults over 55, owing to increased mobility and waning immunity as a result of receiving booster shots earlier than other age groups, according to the study.

The most recent results are from the 19th round of the React-1 trial, which will be the final round as the program concludes at the same time as the United Kingdom reduces the number of free coronavirus tests available.

The Imperial College researchers expressed concern that it may become more difficult to discover developing variations as the government reduces testing.

"There are a bunch of variants out there, and looking at patterns can assist identify variants of concern and ensure that people are aware of what's coming," said Christl Donnelly, an Imperial College professor of statistical epidemiology.