Stanislaus County recommends vaccinated people mask up indoors for 'extra protection' The county noted that a single dose of the Pfizer vaccine is believed to be only 30% effective against the delta strain and urged people to get their second dose "as soon as possible." Share Updated: 4:58 PM PDT Jul 19, 2021 KCRA Staff Stanislaus County recommends vaccinated people mask up indoors for 'extra protection' The county noted that a single dose of the Pfizer vaccine is believed to be only 30% effective against the delta strain and urged people to get their second dose "as soon as possible." Share Updated: 4:58 PM PDT Jul 19, 2021