Yes. Of 469 people infected in a delta-fueled outbreak in Massachusetts in July, 74% were fully vaccinated . A study of the outbreak also found that vaccinated people could carry the virus in their nose and throat, and spread it to others. The CDC recommended mask-wearing in public again, even for those who are vaccinated, partly because of this data. You are much less likely to become seriously ill if you are vaccinated. Wearing a mask in public indoors â€” and outdoors, when you canâ€t stay 6 feet from others â€” will help protect you and those around you.