As the highly contagious Delta variant is sweeping through the United States and other countries across the globe, retailers are reporting new mask shortages, bringing back memories from the pandemic’s debut.

Five states broke records for the average number of daily new COVID cases over the weekend, according to CNBC, despite the fact that this time a significant portion of the population is vaccinated. That’s because Delta is far more contagious than the original strain. For instance, these Chinese researchers previously found that people infected with Delta had about 1,000 times the viral load in their respiratory tract compared to those infected with the original strain. 

Louisiana had 126 cases per 100,000 residents as of Sunday, which is more than three times the national average, while Mississippi and Florida averaged 110 and 101 cases per 100,000 residents, respectively.

“We’re in the middle of the summer, people are gathering again with people, they’re in large groups, the vaccine has given a false sense of security in some ways to people, and they forget,” Dr. Perry Halkitis, dean of the Rutgers School of Public Health, told CNBC 

As a result of these surges in cases, many cities, businesses, and even entire states have reintroduced mask mandates, which has driven up the sale of cloth and surgical masks. Mask sales in the last week of July were up 51% over the week prior, according to Adobe’s Digital Economy Index, which tracks more than 1 trillion visits to U.S. retail sites.

However, this is as good a time as any to have a conversation about mask quality. You see, at the beginning of the pandemic, public health experts were very wary about what guidelines to issue concerning face covering. That’s because they were concerned that people would start hoarding vital medical supplies, leading to dangerous shortages for medical workers.

Although manufacturers and retailers are now reporting trouble keeping up with this recent heightened demand, the supply chain for personal protection equipment is much more robust than in early 2020. Back then, people were advised to use whatever they could find, even if that meant making a cloth mask with their own hands at home. Some facial covering is better than nothing at all, the thinking went.

But we’re past that now. Experts advise that people buy quality masks with a very tight fit that offer much more reliable protection from infection, especially for those who are unvaccinated or part of vulnerable populations.

“A cloth mask surely can give you some protection. But it’s not the kind of protection that you’ll get when you use a much more effective mask. We have not talked about that nearly enough,” Michael Osterholm, leading epidemiologist and Director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told NBC’s Meet the Press.

According to Axios, N95 and KN95 are the most effective face coverings, followed by surgical masks, and then by cloth masks with a double layer. N95s are not suitable for children for all-day wear, who should wear a mask that has at least two layers.

You can find a list of reputed N95 mask resellers in the United States here.