CONTRA COSTA COUNTY (CBS SF) — Health officials in Contra Costa and Sonoma counties on Tuesday confirmed four cases of coronavirus were being treated at local hospitals as the Centers for Disease Control and Prevention warned of the growing risk of a global pandemic.

Two of the patients were transported to Contra Costa County early Tuesday morning from Travis Air Force Base in Solano County. The third patient was already in a county hospital since last week, and they tested positive on Tuesday.

Late Tuesday afternoon, Sonoma County health officials confirmed one case of coronavirus was being treated at a county hospital after being transported from Travis AFB Monday night.

The patients, who were among the recent U.S. evacuees from the quarantined Diamond Princess cruise ship in Japan, were receiving care in Contra Costa due to a lack of space at facilities closer to the base that can properly isolate them to minimize the risk of spreading the virus.

While the three patients have tested positive for COVID-19, they haven’t begun to show symptoms of the virus, such as fever and difficulty breathing. However, the CDC’s agreement with the Department of Defense requires any evacuee who tests positive to be moved from the base.

“Our county’s healthcare system is prepared to handle COVID-19,” said Contra Costa Health Services Dr. Chris Farnitano. “We have been working with our hospital partners to follow safety protocols to keep patients and healthcare workers safe and minimize the risk of the virus spreading in Contra Costa.”

The addition of the four new cases among Diamond Princess passengers evacuated to Travis raises the national case count to a total of 58.

Earlier Tuesday, CDC officials announced that COVID-19 was edging closer to becoming an official pandemic.

Dr. Nancy Messonnier with the CDC said it is not a matter of if, but when the new virus will spread in the U.S. and how many Americans will have severe illness.

The doctor said the U.S. needs to employ new strategies to blunt impact of disease and slow spread after global reports of additional cases occurring without any known source of exposure in Italy and South Korea.

However, the CDC believes the U.S. strategy currently in place has slowed the coronavirus entry and spread and that containment in the U.S. has been successful so far.

CDC officials said they were currently seeing no community spread, but with no vaccine to protect against disease, no medicine to treat COVID-19 and more countries reporting cases of community spread, containment at U.S. borders will be much harder.

That is why the CDC believes it’s a matter of time before the virus will spread in U.S.

Messonnier cautioned the public to prepare for possible disruptions to their daily lives — including school closures, required telecommuting and delays to having elective medical procedures — as efforts to contain and control the possible spread of COVID-19 in the U.S. may accelerate in the coming weeks.

The CDC has issued travel advisories for U.S. citizens to avoid nonessential travel in China and South Korea and to practice enhanced precautions if traveling in Japan, Iran or Italy.

Comments