A University of East Anglia study found that wearing face masks did not significantly reduce the risk of coronavirus infection after the initial Omicron surge. The study analyzed changes in infection risk factors as the pandemic evolved, noting that the importance of factors such as mask use, household size, and occupational exposures changed over time. This study, funded by the National Institute for Health and Care Excellence, highlights the need for adaptable risk management strategies and further research to understand these dynamics.
New study shows face masks did not significantly reduce risk of coronavirus infection after initial omicron wave, calls for adaptable strategies and further research as risk factors evolve is emphasized.
New findings from the University of East Anglia suggest that wearing face masks did not reduce the risk of coronavirus infection after the initial rise in the Omicron variant. Analysis of official data shows that risk factors for infection changed markedly when the dominant new coronavirus variant in the UK shifted from Delta to Omicron in December 2021.
These include mask-wearing, international travel history, number of people in the household, whether they are working or retired, and contact with children or people over 70.
Lead author Professor Paul Hunter, from the University of East Anglia’s (UEA) Norwich Medical School, said: “At the beginning of the pandemic, a number of studies were published looking at risk factors for coronavirus infection, but in the first year… “After that point, there was far less research.” . Our study shows that several risk factors changed around the time the Omicron BA.2 variant became dominant. ”
Co-author Dr Julie Brainard from UEA Norwich Medical School said: ‘Laboratory evidence suggests that the Omicron variant is more likely to infect cells lining the upper respiratory tract than previous variants and is more transmissible. This is not surprising at all, as evidence suggests that there is a strong contagious. Infection risk management must be agile and adapt to better information as outbreaks evolve and emerge. Preventing infection requires a good understanding of which factors are most or least relevant. If these factors are likely to change, we should pay attention to them. ”
Key findings from methodology and data
Researchers analyzed data from the UK’s Office for National Statistics (ONS) coronavirus survey. This study estimated the number of infected people by comparing the infection rate with the current population and household survey. The ONS also asked people questions about their circumstances and habits between November 2021 and May 2022 to see whether those factors could be associated with their risk of testing positive.
Professor Hunter added: “We used this dataset to examine constancy or change in the importance and direction of potential risk factors for a positive test. To do this, we used meta-regression We applied a statistical method called “.
The study found that changes in risk factors included:
- As of November 2021, always wearing a face mask at work, school, or in an enclosed space was associated with a lower risk of infection for both adults and children, but After that it wasn’t like that.
- Living in a house with more than five people was initially a risk, but by the end of the study period, people in large households (four or more people) had a negligible risk than people living in single-person households.
- Although early international travel was not associated with increased risk, it was later associated with increased risk.
- Working in the health and social care sector or coming into contact with others was often found to be important in the first year of the pandemic, but the overall risk of infection increased or changed during the study period. was not related.
- Ethnic minority status was strongly associated with increased risk in the first months of the UK outbreak, but was associated with decreased risk during the entire monitoring period of the study, with no significant trend change. .
- Being retired was associated with lower risk compared to those in work overall, but by February 27, 2022, which coincided with the beginning of Omicron’s second wave, no protective effect has also disappeared.
- By the end of February 2022, it was clear that the risk was decreasing for adults living with children under 16 years of age.
- People under 70 who live with someone over 70 were initially less likely to test positive, but this protective effect diminished by around mid-February 2022.
Researchers said there is a balance of evidence that wearing face coverings reduces the transmission of respiratory infections in the community and also reduces the transmission of COVID-19. However, the question is how much?
Conclusions and implications for future research
A systematic review of pre-pandemic evidence and an analysis of original survey data during the COVID-19 pandemic both showed that wearing masks can or does reduce transmission. SARS-CoV-2 Approximately 19%. However, these conclusions were drawn primarily based on data from before the Omicron variants emerged.
This latest study found that before Omicron BA.2, not wearing a mask was associated with an increased risk of about 30% in adults and about 10% in children. However, by Omicron’s second wave (after mid-to-late February 2022), mask-wearing for adults had no protective effect and likely increased the risk of infection for children.
Professor Paul Hunter commented: “With a highly contagious disease such as coronavirus with short duration of immunity, it is not surprising that risk factors change during a pandemic.” The so-called SEIRS (Susceptibility, Exposure, Infection, Recovery, Susceptibility) model of epidemics suggests that once an infectious disease becomes endemic, the risk factors that caused the epidemic in the early stages become less important and the rate at which people lose immunity becomes more important. I predict that will happen. This causes an increase in the infection rate. ”
Dr Brainard added: “Many of the potential risk factors for contracting coronavirus have not changed over this period and it is important to know that.” Although we offer several possible explanations for why the changes occurred, more focused research is needed to definitively understand why there were changes in some risk factors. ”
Reference: “Changing Risk Factors for the Development of SARS-CoV-2 Infection” (Paul R. Hunter and Julii Brainard, From Delta to Omicron), May 15, 2024. pro swan.
DOI: 10.1371/journal.pone.0299714
The research was carried out by the National Institute for Health and Care Research (NIHR) Health Protection Research in Emergency Preparedness and Response at King’s College London, in partnership with the UK Health and Safety Agency (UKHSA) and in collaboration with the University of East Anglia. Funded by the unit.
