Prominent public health officials have increasingly highlighted the limitations of cloth face masks, pushing for more effective respirator masks such as N95s as omicron engulfs the United States, a shift in messaging from earlier in the pandemic.

Officials encouraged the use of cloth masks in the spring of 2020 as a desperate measure to slow the spread of COVID-19 after previously recommending against masks and continued to boost them in the months after. Now, though, more experts are saying that the masks are not helpful.

“Cloth and surgical masks do absolutely nothing for protection from ambient virus,” said Chad Roy, a microbiologist at Tulane University School of Medicine, referring to the virus spreading through the air. “All this song and dance of wearing cloth masks with some presumption that you’re being protected from ambient virus is completely and positively 100% counter to how masks and respirators work.”