Masks are now required indoors at San Diego Unified School District schools, offices

Indoor mask mandates returned Monday for the San Diego Unified School District schools and offices as COVID-19 cases and hospitalizations tick up in the county.

Mandatory masking in indoor public spaces will be required for all students, teachers and staff at least through the end of summer school.

"As a district, since the start of the COVID-19 pandemic, we have been intentional in implementing strategies to keep our community safe and reduce absences due to illness -- all in service of our students, staff and community," the district said in a letter sent to staff, parents and students Friday.

"If your student is participating in summer school or other summer enrichment program, please send them to school or their program with a mask. If they do not have one, masks will be provided. Students and staff will be required to wear their masks while indoors only," the letter said.

The district added in the letter that it will continue to monitor data from the Centers for Disease Control and Prevention and the county over the next two weeks and let the community know if there are any changes.

"This is getting used to the new normal and getting people to be responsible for their protection," Dr. Francesca Torriani, program director of infection prevention and clinical epidemiology and tuberculosis control at UC San Diego Health, told ABC News. "So we get used to mitigating when cases rise and then go back to normal life when waves subside."

SDUSD dropped its mask mandate in April following a decrease in COVID-19 cases, hospitalization and deaths. However, in May, the district said the mandate would return as long as the county was classified by the CDC as having high transmission levels of COVID, which is determined by case counts and hospital admissions.

"Staff had been monitoring what's happening in the community with COVID and, as a result of that, they determined that we reached that magical point that the board had said was time to go back and mask up again," Sharon Whitehurst-Payne, president of the SDUSD Board of Education, told ABC News.

Over the last seven days, San Diego has recorded 383.01 new cases per 100,000, a nearly 5% jump from the previous week, according to CDC data. Additionally, the county has seen a hospital admission rate of 11.8 per 100,000 over the last seven days, which is a 31% spike compared to the previous seven days.

Whitehurst-Payne said the indoor mask mandate will continue into the fall semester if the county is still in the CDC's "high" tier, but it will be dropped if the county enters a lower tier. She added that she understands some parents' frustration, but it is a question of safety.

"Our number one priority is keeping our students safe," she said. "When we realize we could do something to keep students safe, we want the greatest safety for your child."

Schools in San Diego are not the only locations seeing the return of masks. Naval Base Coronado and Naval Base San Diego both announced on social media that mask mandates will go into effect Monday.

"Effective TODAY, mask-wearing is required indoors on all Naval Base Coronado Installations and training sites until further notice," the base wrote in a Facebook post. "Please do your part to reduce the spread by wearing a mask, maintaining social distancing, increased hygiene practices and vaccinations."