STANISLAUS COUNTY (CBS13) – Some residents in Stanislaus County are now being urged to wear masks indoors, even if fully vaccinated, as COVID-19 cases continue to rise.

The recommendation from the county asks those 65 and up, or those who live with others that are 65 and older, have risk factors for the virus or have any medical conditions to mask up indoors.

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Public health officials said the county saw an abrupt rise in infections last week, which nearly doubled the new case count of the week prior. The county said the rise can be attributed to the coronavirus Delta variant and the many residents who are not yet fully vaccinated.

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Public health officials in the county said fewer than half – 45% – of residents aged 12 and older are fully vaccinated.

“There is much unknown about the Delta variant, such as whether this variant causes more severe disease, but we do know that this variant is about 2 times more transmissible than the original coronavirus strain,” the county said in a news release Monday.

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Other counties across the region, like Sacramento and Yolo, have already made the same recommendation for fully vaccinated as the Delta variant continues to drive the increase in infections.