Two-thirds of people recently infected with the Omicron variant say they had already had COVID before. The findings come from a large, continuing study, React, swab-testing thousands of volunteers in England. More work is needed to know how many are true reinfections, but the results reveal the groups that appear to be more likely to catch COVID-19 again.
They include healthcare workers and households with children or lots of members under one roof. The study has tested over two million people. The latest findings for the first two weeks of 2022—round 17—are based on about 100,000 polymerase chain reaction (PCR) tests posted to volunteers and then returned.
About 4,000 were positive, by far the highest rate seen since the pandemic began. When a selection of them was sequenced to check what type of COVID was to blame, virtually all were Omicron, the highly infectious variant first identified in South Africa, causing a big winter wave of infections in the UK.
It is not yet clear how many of the volunteers who tested positive had been fully vaccinated. Two shots offer little protection against catching Omicron, although protection against severe disease wanes. Since the outbreak of Omicron, there has been a rapid rollout of booster doses to enhance people’s protection.