SAN MATEO COUNTY (CBS SF) – Officials in San Mateo County said all visitors to county facilities will again be required to wear a face covering indoors regardless of vaccination status, amid rising COVID-19 cases due to the Delta variant.

The requirement, which will go into effect on Monday, is similar to the masking rules that were in place at county facilities before the state’s full reopening on June 15.

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Since the reopening, the 7-day average of new cases per 100,000 people in San Mateo County has risen from 1.3 to 5.2. Meanwhile, the test positivity rate has also risen from 0.4% in mid-June to 2.6%.

Hospitalizations have also risen in the last week. As of July 14, four people were hospitalized with COVID-19. Officials said Thursday the number of hospitalized with the virus has risen to 15, with six people in the ICU.

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The rise in cases comes as the more contagious Delta variant has become the dominant strain in California, largely infecting the unvaccinated.

“The increasing case numbers are a harsh reminder that we are not done with COVID and COVID is not done with us,” County manager Mike Callagy said Thursday. “Let’s all continue to do our part by getting vaccinated and taking common-sense precautions so we can keep all of us safe.”

County officials again stressed the need to be vaccinated, saying the shots are effective against COVID-19 and the variants. As of Tuesday, 588,700 people in the county have at least one dose of vaccine, which amounts to 88.4% of eligible residents. More than 524,000 county residents are fully vaccinated.

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Vaccines are readily available throughout the county at clinics, pharmacies and through private health care providers. Information about county vaccination clinics can be found on the county’s health website.