NAPA (CBS SF) — The death toll from the coronavirus outbreak grew to 63 late Tuesday when Napa health officials announced the county’s first death from the illness.

Napa County Public Health Officer Dr. Karen Relucio said the death occurred on March 31st.

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She said the patient was being treated at a local hospital. Pending notification of immediate family and due to confidentiality laws, no other information was being released at this time.

“Our hearts go out to the patient’s family, and friends during this difficult time,” Relucio said. “More than ever, it is crucial that we practice physical distancing, and if we are sick, even with mild illness, make every effort to self-isolate from others and follow the shelter at home order.”

Health officials said Napa County also has had 16 confirmed cases of the virus.

Solano County currently was the only one of the Bay Area’s 10 counties not to have reported a death during the outbreak that began in late January.

Santa Clara County has been the hardest hit among all the local counties with 30 deaths as of Tuesday.

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While the number of new cases and deaths have been foremost in local residents minds, state leaders and health officials say they are increasingly focused on a different metric. They are using the number of people arriving at the hospital.

“The number of hospitalizations, the percentage increase of 13%, intensive care units 10%,” explained California Governor Gavin Newsom. “That is in line with some of our modeling.”

For the second day in a row on Tuesday, the governor zeroed in on those specific numbers.

“I think we want to basically look at things that we can count with some consistency,” says UC Berkeley epidemiologist Art Reingold. “One of them is deaths, and one of them is hospitalizations.”

Reingold says the test results everyone has been following only tell part of the story. When it comes to how many people are infected, the virus itself is probably a more reliable indicator. That is because the percentage of people who get really sick from it is relatively consistent.

“Everything else, numbers of people positive, are really subject to the amount of testing going on, so they’re really hard numbers to interpret,” Reingold says of the numbers. “We think that hospitalizations are a better indicator, yes.”

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But the positive test results do give some evidence as to spread, and that is where there is some reason for early, cautious optimism in the Bay Area.