Rochelle Walensky, CDC director, Wilmington, Delaware, December 8, 2020 Kevin Lamarque/ReutersOn Tuesday, the CDC updated its guidelines to recommend indoor masks for all vaccinated persons.According to the CDC, the Delta variant makes it easier to transmit the virus to people who have been vaccinated.People infected by Delta virus may have similar viral loads, whether they are vaccinated or not.Check out more stories from Insider's business page.The Centers for Disease Control and Prevention has updated its guidelines for mask use due to new science. On Tuesday, the CDC recommended that people who have been fully vaccinated wear masks indoors "in areas of substantial and high transmission." This includes large areas of the US, including most of the South.The CDC advised that teachers, staff, students and visitors to K-12 schools cover up.These new guidelines are designed to protect others and prevent the spread of the Delta variant, according to Rochelle Walensky, CDC director.In May, the CDC stated that people who have been vaccinated don't need to wear masks. This recommendation was partly based on data that showed that people who had been vaccinated were less likely than others to spread the virus. Walensky stated that the Delta strain, which is now the predominant strain in the US, behaves differently to previous versions.Walensky stated Tuesday that information from several countries and states about the Delta variant suggests that some people vaccinated with the virus may become contagious, spreading the virus to others. "This new science is alarming and it unfortunately warrants an update of our recommendations."Walensky stated that CDC investigations revealed that the level of Delta virus in vaccinated individuals infected is the same as the levels in people who have not been vaccinated. This is a sign that people vaccinated can transmit the virus, even though they are less likely to become ill.Continue the storyWalensky said that "the vast majority" of transmission, severe disease, hospitalizations, and deaths occur among people who have not been vaccinated.According to the CDC, 97% of COVID-19 hospitalizations in the US are due to unvaccinated individuals. Walensky stated that vaccines can reduce sevenfold the chance of developing symptomatic Delta infections. She also said that the risk of death and hospitalization from Delta drops by twentyfold when someone is vaccinated.Walensky stated that in areas with high transmission, approximately 1 in 20 or even 1 per 10 people's contacts could be at risk for a breakthrough infection. This is a condition where a case of the disease has been diagnosed and treated. This assumes vaccines are 90%-95% effective.Still, vaccines work well against DeltaIn March 2021, an Ohio resident received a COVID-19 vaccination. Stephen Zenner/SOPA Images/LightRocket via Getty ImagesVaccines against Delta seem to be slightly less effective than other strains. The risk of developing symptomatic Delta infections by Pfizer's two dose vaccine was found to be 88% lower than the 95% for the original strain in a recent study published in the New England Journal of Medicine. Only 36% of those at risk were able to receive the vaccine in one dose.A Canadian study, which is still in the process of peer review, found that one dose of Pfizer’s shot was effective in preventing symptoms caused by Delta within two weeks. Moderna's shot was at 72%.Because Johnson & Johnson's shot is less effective than Moderna's or Pfizer's, breakthrough infections may be more common. In clinical trials, J&J's shot cut the risk of severe and moderate COVID-19 infection by 66%. South African researchers discovered that 94% (including those caused by Delta) of the breakthrough infections in J&J recipients were mild.Although Delta is more easily spreadable than other strains, it can still cause more deaths and hospitalizations among those who have been vaccinated.Public Health England's analysis found that Delta had a 60% higher risk of household transmission than the Alpha variant, but more recent estimates indicate that the difference may be closer to 40%. According to the CDC, the Alpha variant is now about 50% more transmissible that the original strain.Business Insider has the original article.
