COVID-19 vaccines may reduce transmission, experts say, but vaccinated Americans still need to wear masks in public. Here's why.
When COVID-19 vaccinations began, U.S. health officials encouraged vaccinated Americans to continue wearing masks in public because scientists were still unsure if they could carry the virus that causes the disease after being inoculated.
Recent results from real-world studies show the COVID-19 vaccines protect against asymptomatic infection, suggesting they also drastically reduce virus transmission.
But health experts still recommend wearing masks in public, regardless of vaccination status, as more research is needed to confirm whether vaccinated people can spread the virus and as variants become more prevalent in the U.S. and states see cases spikes.
The nuanced messages are understandably confusing, especially to pandemic-fatigued Americans eager to return to normal. As hopeful news continues to emerge, health experts urge people to remain vigilant a little while longer.
“Because vaccinations do dramatically reduce transmission, eventually the CDC will issue new (masking) recommendations for vaccinated individuals,” said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. “But it won’t happen until the summer at the earliest, and all this depends on getting the B.1.1.7 variant (first identified in the U.K.) under control and expanding vaccination coverage.”
Preliminary information from Israel found people who received the Pfizer-BioNTech vaccine did not develop COVID-19 symptoms or transmit the disease, according to a Pfizer statement released March 11.
“It looks like 90% reduction in asymptomatic transmission. So that’s really good,” Hotez said when the data was made available. Practically speaking, that means the vaccine may enable people to produce antibodies that reduce virus levels in the nose and the mouth, making them less likely to be contagious.
Indoor, small group guidelines: Vaccinated Americans can gather inside without masks or social distancing in certain circumstances, CDC guidelines say
In a report published Monday, the Centers for Disease Control and Prevention found the Pfizer and Moderna mRNA vaccines were 90% effective against SARS-CoV-2 infection, including asymptomatic infection, among front-line essential workers.
Pfizer also released study results Wednesday showing its mRNA vaccine with German partner BioNTech was still more than 90% effective six months after receiving a second dose, even against the B.1.351 variant first identified in South Africa.
Dr. Anthony Fauci, the nation's leading expert in infectious diseases, expressed optimism during a White House briefing Friday but added more data is needed to confirm the vaccines' effectiveness on variants.
"So the bottom line message is that vaccines work very well in the real-world setting," he said. "Very, very good reason for everyone to get vaccinated as soon as it becomes available to you."
While these studies are promising for ending the pandemic, health experts say it's too soon for the nation to ditch masks and return to normal.
Scientists are specifically concerned with how vaccines will stack up against virus variants containing the E484K gene, which may reduce vaccine effectiveness, said Dr. Paul Offit, director of the Vaccine Education Center and an infectious disease specialist at Children’s Hospital of Philadelphia.
The variants that contain this mutation include the B.1.351 variant first identified in South Africa, the P.1 variant identified in Brazil and the B.1.526 variant, which may be driving New York’s surge in coronavirus cases.
“They have an advantage, they’re more contagious and by some extent, they resist immunity,” Offit said.
Research has shown non-mRNA vaccines developed by two manufacturers – Johnson & Johnson and Novavax – were still effective, but less so against the B.1.351 variant compared to the original coronavirus strain
In a clinical trial in South Africa, the Novavax vaccine prevented 60% of mild, moderate and severe COVID-19 cases caused by the variant compared to more than 95% of cases caused by the original virus strain, according to a company statement released in January.
And while transmission may be greatly reduced by vaccines, the chances of spreading the virus is not zero, said Michael Mina, an infectious disease epidemiologist at the Harvard T.H. Chan School of Public Health.
People should continue to diligently wear their masks, regardless of vaccination status, until cases are low.
“We’ve gone through hell to get to where we are today and the last thing we want to do is keep going through hell,” Mina said. “Wearing masks is still pretty simple … unless you are in a small space with everyone being vaccinated, I would say err on the side of caution for a little bit longer.”
Contributing: Karen Weintraub, USA TODAY. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.
Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.
This article originally appeared on USA TODAY: COVID vaccines reduce transmission, but still wear a mask, experts say