SAN FRANCISCO (CBS SF) – Health officers across the Bay Area renewed calls for people to get COVID-19 booster shots Friday, as many have yet to receive their third dose while the omicron variant rapidly spreads across the region.

“Many more cases of Omicron are expected to be reported in the coming days and weeks and based on the exponential growth in cases being seen in Europe, there is a significant risk of exponential growth in COVID-19 cases in our region in the coming weeks,” said a statement signed by health officers in all nine Bay Area counties, Monterey and Santa Cruz Counties, along with the City of Berkeley.

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Officials predicted rising cases as other highly-vaccinated countries were reporting rapidly increasing COVID-19 infections. “Other highly vaccinated countries that mirror the Bay Area’s high vaccination rates, such as Denmark and Norway, are predicting Omicron will become the dominant variant in a matter of days,” officials said.

In San Francisco, where the first U.S. case of the variant was detected on Dec. 1, testing has determined at least 30 probable omicron cases in the city, which officials said is likely an undercount. The city’s Department of Public Health reports only 44% of those eligible have received a booster.

“Although we have made great progress in our booster uptake in the last several weeks, in the face of Omicron it is vital that all individuals who are eligible make a plan to get vaccinated as soon as possible, especially those at higher risk of becoming severely ill,” San Francisco health officer Dr. Susan Philip said.

Meanwhile in neighboring San Mateo County, officials there report only 34% of eligible residents have received a booster shot. Cases of omicron have not been confirmed on the Peninsula so far, but evidence has been detected in wastewater samples.

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In the East Bay, Contra Costa County officials said less than 32% have received a booster shot, including 246,000 people 50 and older, who are at higher risk. While no cases have been reported in the county, the variant has also been detected in a wastewater sample.

“Even if you were fully vaccinated earlier this year, two shots are no longer enough,” said Contra Costa health officer Dr. Chris Farnitano. “We know protection against infection from the vaccines declines over time, so booster doses are critical for everyone who was vaccinated at least 6 months ago.”

In Alameda County, about 50% of residents have received their booster shots. Many have yet to do so, including 240,000 people who are 50 and older.

The renewed call for boosters comes as Marin and Sonoma counties reported their first cases of the omicron variant, and as officials in Santa Clara County reported 10 omicron variant cases, up from one case a week ago.

“When I look around the corner ahead, what I see is a deluge of omicron. What I see is perhaps one of the most challenging moments we have yet in the pandemic,” Santa Clara health officer Dr. Sara Cody said at a news conference Thursday.

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With the holidays approaching, health officials issued several tips alongside obtaining booster shots, including testing before and after travel, gathering outdoors if possible, along with wearing masks indoors and in crowded settings.