Bloomberg) — Covid-19 infections in England reached their highest level in March since the pandemic began, driven by the omicron subvariant BA.2 and waning immunity among older adults, according to a new study. The overall Covid prevalence rate more than doubled last month from February when infection rates were falling from the omicron-led January peak, the React-1 study led by Imperial College London found. Since then the emergence of BA.2 — a more-transmissible version of omicron- has accelerated new infections and become the dominant strain in England, accounting for about 90% of the samples that tested positive. The higher infection rates may result in an increase in hospitalizations despite the higher levels of vaccination among the population, said Paul Elliott, director of the React program, and chair in Epidemiology and Public Health Medicine, Imperial College London. Rates of Covid-19 are growing among adults over 55 years driven by higher mobility and waning immunity given that they received their booster shots earlier compared to other age groups, the study said. The latest results are the 19th round of the React-1 study and will be the last as the program comes to an end at the same time the U.K. cuts back on free coronavirus tests. The Imperial College researchers raised concerns that it will become more difficult to detect emerging variants as the government scales back testing. “There are a lot of variants out there and it’s looking at the patterns that helps to identify variants of concerns and make sure that people see what’s coming,” said Christl Donnelly, a professor of statistical epidemiology at Imperial. NN: The scientific evidence is clear. It ain’t over. These studies prove the most effective tool we have is vaccination. And they need to be updated every 4 to 5 months.