FULL CLAIM: Unvaccinated people have to wear masks to protect vaccinated people
As of 2 June 2021, more than 136 million people have been fully vaccinated against COVID-19 in the U.S. In parallel, the country has seen a significant decrease in the number of COVID-19 cases and deaths. As of late May 2021, the daily number of new COVID-19 cases fell to its lowest level since late March 2020.
On 13 March 2021, the U.S. Centers for Disease Control and Prevention updated their public health guidelines and stated that fully vaccinated people “can resume activities without wearing a mask or physically distancing” in both indoor and outdoor settings. People are considered fully vaccinated two weeks after their second dose of the Pfizer-BioNTech or Moderna vaccines or after one dose of the Johnson & Johnson vaccine.
On the other hand, unvaccinated people are still required to wear masks indoors and in some outdoor settings, such as crowded places. Facebook posts relayed the claim that the difference in mask-wearing guidelines was because unvaccinated people had to protect vaccinated people from COVID-19. The underlying implication is that the COVID-19 vaccines are ineffective, hence why unvaccinated people are still required to use protective equipment. However, this reasoning is flawed and inconsistent with available evidence, as explained below.
Clinical trials and ongoing monitoring show that vaccinated people are much less at risk of catching COVID-19 or developing a severe form of the disease than unvaccinated people. Therefore, the mask requirement for unvaccinated individuals doesn’t aim to protect vaccinated people. Rather, it aims to protect the unvaccinated population by reducing virus transmission between them.
Large clinical trials involving tens of thousands of volunteers showed that the Pfizer-BioNTech, Moderna, and Johnson & Johnson COVID-19 vaccines reduced the risk of symptomatic COVID-19 by 95%, 94.5% and 66.9%, respectively, in the vaccinated group compared to the group that didn’t receive the COVID-19 vaccine. According to the CDC, these vaccines reduce the number of COVID-19 patients needing hospitalization by at least 89%.
Additional studies also confirmed the effectiveness of the vaccines in the real-world. A study from Israel, one of the first countries to begin mass vaccination, showed that the Pfizer-BioNTech vaccine was 97% effective against symptomatic COVID-19 and hospitalization, in line with the clinical trial results. The effectiveness is calculated by comparing a given clinical outcome such as infection, hospitalization, or death between the vaccinated and unvaccinated groups. Therefore, those results indicate that vaccinated individuals are comparatively more protected from the disease than unvaccinated people.
Importantly, studies also showed that vaccinated people are much less at risk of transmitting the disease than their unvaccinated counterparts. Summarizing the available evidence, the CDC reported that the vaccines are approximately 90% effective against SARS-CoV-2 infection, including asymptomatic cases. When people aren’t infected, it follows that they cannot transmit the disease. Thus vaccination helps reduce the spread of the virus among the population.
In summary, the existing evidence shows that, in settings with a mix of vaccinated and unvaccinated people, unvaccinated individuals are more at risk of being infected and transmitting the virus. This is why CDC guidelines relaxed mask-wearing guidance for vaccinated people, but not unvaccinated people.