Health Insider: Valley doctor weighs in on concerns over Delta variant, new mask guidance World Health Organization and some Valley doctors encouraging everyone to wear a mask. and last updated 2021-06-30 01:41:58-04 During a press conference on Friday, officials with the WHO noted that to help reduce the community spread of COVID-19, those who are fully vaccinated should still take some precautions. The recommendation comes as countries around the world are imposing new health restrictions to combat the spread of the Delta variant â a more contagious mutation of the virus that officials suspect is 50 to 60% more contagious than the Alpha variant of COVID-19, which was first observed in the U.K.