(Epoch Health) People who wore protective masks were found to be more likely to contract COVID-19 infections than those who didn’t, according to a recent Norwegian study.
Among individuals who “never or almost never” wore masks, 8.6 percent tested positive. That rose to 15 percent among participants who “sometimes” used masks, and to 15.1 percent among those who “almost always or always” wore them.
Adjusting for factors such as vaccination status, the study determined that individuals who sometimes or often wore masks had a 33 percent higher incidence of COVID-19, compared to those who never or almost never wore masks. This jumped to 40 percent among people who almost always or always wore them.
However, adjusting for “differences in baseline risk over time,” the risk of wearing masks turned out to be “less pronounced,” with only a 4 percent higher incidence of infection among mask-wearers.
“The results contradict earlier randomized and non-randomized studies of the effectiveness of mask-wearing on the risk of infection,” the researchers wrote.
“Most of these studies reported that wearing a face mask reduces the risk of COVID-19 infection. Some observational studies have reported manyfold reductions while one community-based randomized trial failed to demonstrate a statistically significant reduction in infection risk and one cluster randomized community trial found only a modest reduction.”
The researchers pointed out a major limitation of their study: Individuals who used masks may have done so to protect others from their own infection. This could explain the “positive association between risk of infection and mask usage.”
Behavioral differences and the fact that the survey was based on self-reporting could also contribute to bias, it stated.
There’s also a possibility that mask wearers felt safe while wearing masks and thus didn’t follow other regulations such as social distancing, which raised their risk of contracting COVID-19, the study said.
“Our findings suggest that wearing a face mask may be associated with an increased risk of infection. However, it is important to note that this association may be due to unobservable and non-adjustable differences between those wearing and not wearing a mask,” the researchers stated.
“Therefore, caution is imperative when interpreting the results from this and other observational studies on the relationship between mask-wearing and infection risk. Recommendations to wear face masks in the community are largely informed by low certainty evidence from observational studies.”
Researchers called for more trials and studies to gain a better understanding of the effectiveness of wearing masks against transmission of respiratory pathogens.
The study was fully funded by the Norwegian Institute of Public Health. It reported no conflicts of interest.
The new study comes at a time when some regions in North America are reinstating mask mandates amid a reported increase in COVID-19 cases.