RELATED: Pfizer Only Works Against the Delta Variant If You Do This, New Study Says. A study published July 30 in Scientific Reports used mathematical models to predict the likelihood of the coronavirus further spreading and changing. The researchers found that although a fast rate of vaccination decreases the possibility of the virus changing and evolving, it may not be enough if other restrictions have been lifted. In fact, the researchers say increased vaccinations alongside lifted COVID precautions could actually result in more vaccine-resistant variants.ae0fcc31ae342fd3a1346ebb1f342fcb “When a relaxation of non-pharmaceutical interventions happened at a time when most individuals of the population have already been vaccinated, the probability of emergence of a resistant strain was greatly increased,” the study authors explained. According to the study, non-pharmaceutical interventions, like masks and social distancing, must still be in place for people—including those already vaccinated—to remain protected against the Delta variant and other emerging variants “throughout the entire vaccination period.” “When most people are vaccinated, the vaccine-resistant strain has an advantage over the original strain,” study co-author Simon Rella, with the Institute of Science and Technology Austria explained, per CNN. “This means the vaccine resistant strain spreads through the population faster at a time when most people are vaccinated.” But according to Rella, “There is a chance to remove the vaccine resistant mutations from the population,” if these COVID precautions are maintained. RELATED: For more up-to-date information, sign up for our daily newsletter. The study supports a recent decision from the Centers for Disease Control and Prevention (CDC), in which the agency reversed mask guidance for some vaccinated individuals on July 27. The CDC says vaccinated people in the U.S. should go back to wearing masks in areas where there are more than 50 new infections per 100,000 in a week. The revamped guidelines may not go far enough, however. A leaked internal CDC document, published by The Washington Post on July 29, says that “given higher transmissibility and current vaccine coverage, universal masking is essential to reduce transmission of the Delta variant.” The study in Scientific Reports would agree. “The individual who is already vaccinated and putting on a mask should not think this is pointless but should think that there is a vaccine-resistant strain running around,” study co-author Fyodor Kondrashov, PhD, also with the Institute of Science and Technology Austria, said. “By preventing spread of vaccine resistant strains, you are preventing evolution of this virus.” RELATED: Vaccinated People Who Get the Delta Variant Have This in Common, WHO Says.