San Mateo County reported nine additional deaths, Alameda County recorded three and Santa Clara County two more before 3 p.m. The 14 new deaths pushed the Bay Area total past 400 with several counties not yet reporting for the day.
The Bay Area has averaged five to seven deaths a day in May, and was averaging about nine a day at the peak of the outbreak in mid April. Prior to Tuesday, there was only one double-digit total in the past two weeks.
“Two days is too short of a period of time to define it as a trend,” said John Swartzberg, a UC Berkeley infectious disease expert.
Even as San Francisco, along with much of the rest of the Bay Area, moved into phase two of Gov. Gavin Newsom’s statewide reopening plan on Monday, Dr. Grant Colfax, the director of the city’s Department of Public Health, cautioned that the virus remains unpredictable.
“It’s really important to emphasize, while we’re hopeful, that the situation can change quickly,” he said during his morning briefing with Mayor London Breed. “When this virus takes off, it takes off really fast.”
San Francisco confirmed 48 new cases of the coronavirus on Tuesday, bringing the number of known cases in the city to 2,179. The Bay Area had 11,286 cases and 402 deaths as of Tuesday afternoon.
Swartzberg emphasized the new case and death numbers do not reflect the current state of the outbreak, but what was happening two to five weeks ago. The virus has an incubation period of up to two weeks, and people who die generally do so three to five weeks after they are infected.
“The reason we’re seeing the numbers plateau is because people sheltered in place,” he said. “We could be having a surge right now. We need much more rigorous application of testing to know where we are.”
Prior to Sunday, the last day without a reported virus-related death in the Bay Area was March 21. The last consecutive days without one were March 10-12, days before the shelter-in-place was ordered in the region and state. The Bay Area reported 20 deaths April 22.
Several Bay Area counties have reported small upticks in cases recently, which public health officials say may be due to some easing of stay-home restrictions — such as allowing construction to resume earlier this month — as well as increased testing.
But other counties, most noticeably Santa Clara, have seen a clear drop or a plateau in the number of cases over the past week or two. This week, all Bay Area county health officers said they were encouraged by signs that the regional outbreak has slowed and are prepared to continue, in some places very gradually, reopening the economy.
Swartzberg said the numbers may shoot up again as shelter-in-place restrictions are loosened around the Bay Area.
“It’s still a question mark,” he said. “The lack of deaths is great to see, but that’s not telling us anything about where we’re at today. We know there will be more cases when people stop sheltering in place but we don’t know how many.”
Aidin Vaziri is a San Francisco Chronicle staff writer. Email: [email protected]