By the second Omicron wave, wearing masks was shown to offer no protection for adults and potentially increased the risk of infection in children.
At the onset of the COVID-19 pandemic, masks were a recommended public health measure to prevent transmission of the virus. Yet new research suggests masks were ineffective at reducing the risk of infection when Omicron became the dominant variant.
In a study published in PLOS ONE, researchers found that several risk factors for infection, including wearing a mask, changed significantly in December 2021 when Omicron became the dominant SARS-CoV-2 variant.
To help explain why some interventions were associated with a decreased risk of infection early in the pandemic but were less protective or associated with an increased risk later on, the researchers examined survey data from the UK Office of National Statistics (ONS) from 200,000 people who were tested for COVID-19 every two weeks.
Along with publishing data on disease prevalence, the ONS asked people questions about their circumstances and habits from November 2021 to May 2022 to determine whether certain risk factors were associated with positive COVID-19 tests. This time period covered multiple SARS-CoV-2 variants, including the final few weeks of the Delta variant and Omicron variants BA.1 and BA.2.
According to the study, adults and children who consistently wore masks at work, school, or in enclosed spaces prior to November 2021 had a reduced risk of infection, but not after the onset of the first wave of Omicron.
During the first wave of Omicron, never wearing a mask was associated with an increased risk of infection of about 30 percent in adults and 10 percent in children. But by the second wave, driven by the BA.2 subvariant from February 2022 onwards, wearing a mask offered no protection for adults and potentially increased the risk of infection for children.
“Early in the pandemic there were many studies published looking at risk factors for catching COVID, but far fewer studies after the first year or so. Our research shows that there were changes in some risk factors around the time the Omicron BA.2 variant became dominant,” lead author Dr. Paul Hunter of Norwich Medical School at the University of East Anglia, said in a news release.
By Megan Redshaw, J.D.
