WASHINGTON — The US Centers for Disease Control and Prevention on Tuesday issued new guidance on outdoor mask use for fully vaccinated Americans. Fully vaccinated people can now unmask at small outdoor gatherings, or when dining outside with friends from multiple households. The CDC is telling unvaccinated people that they still need to wear a mask at such gatherings. "If you are fully vaccinated and want to attend a small outdoor gathering with people who are vaccinated and unvaccinated, or dine at an outdoor restaurant with friends from multiple households, the science shows if you are vaccinated, you can do so safely unmasked," CDC Director Dr. Rochelle Walensky said during a virtual White House briefing on Tuesday. "Generally, for vaccinated people, outdoor activities without a mask are safe. However, we continue to recommend masking in crowded outdoor settings and venues, such as packed stadiums and concerts where there is decreased ability to maintain physical distance and where many unvaccinated people may also be present," Walensky said. "We will continue to recommend this until widespread vaccination is achieved." But life will not return completely to normal for fully vaccinated people. The federal health agency says even if you"ve been vaccinated, you should avoid large indoor gatherings. The CDC did not define how many people would be in a large gathering. For the fully vaccinated who do choose to attend a crowded outdoor event, such as a live performance, parade, or sporting event, wearing a mask is recommended. The CDC advises vaccinated people to still wear masks in indoor public spaces, such as a mall, movie theatre or museum, the CDC continues to recommend wearing a mask. CDC Director Dr. Rochelle Walensky announced the new outdoor mask recommendations on Tuesday. People are considered fully vaccinated by the CDC two weeks after the second dose of the Pfizer/BioNTech or Moderna vaccines or two weeks after the single-dose Johnson & Johnson vaccine. President Joe Biden is expected to reference the updated guidance for wearing masks outdoors while giving remarks on the state of the pandemic on Tuesday, ahead of his first address to Congress on Wednesday. One of Biden"s top coronavirus advisers, Dr. Anthony Fauci, strongly hinted to CNN that the guidance would be updated this week. Fauci told CNN"s Jim Acosta on Sunday that he didn"t want to get ahead of the CDC but the agency "will be coming out with updating their guidelines of what people who are vaccinated can do and even some who are not vaccinated." On Tuesday morning, before the updated mask guidance was announced, US Health and Human Services Secretary Xavier Becerra said on CBS This Morning that people who are vaccinated against Covid-19 will be able to return to a more normal lifestyle. "The message is clear. You"re vaccinated, guess what, you get to return to a more normal lifestyle. If you"re not vaccinated, you"re still a danger. You"re still in danger as well," Becerra said. "So get vaccinated." Changes motivated by science The CDC says it was motivated to update its guidance for fully vaccinated people after seeing a rise in the number of vaccinated people and a fall in the rates of COVID-19 cases, CDC Director Dr. Rochelle Walensky said during a virtual White House briefing on Tuesday. "There are increasing data that suggests that most of the transmission is happening indoors rather than outdoors -- less than 10 percent of documented transmission in many studies have occurred outdoors," Walensky said. We also know that there"s an almost 20-fold increased risk of transmission in the indoor setting than in the outdoor setting. That, coupled with the fact that we now have 37% of people over the age of 18 fully vaccinated and the fact that our case rates are now starting to come down, motivated our change in guidance," Walensky said. "As more people get vaccinated and as case rates continue to come down, we will come up with further updates." — CNN