MARIN COUNTY (CBS SF) — A spike in cases attributed to spring break travel earlier in April has kept Marin County from moving into the most-relaxed COVID reopening tier Tuesday, according to state officials.

The updated tier assignments announced just before noon on Tuesday on the state’s Blueprint for a Safer Economy website showed that only three counties in California — Alpine, Sierra and Lassen — were in the Yellow Tier. All Bay Area counties are currently at the Orange Tier with the exception of Solano County, which remained at the Red Tier.

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Marin County health officials indicated that spring break travel likely led to the recent increase in coronavirus cases in the county. The Yellow Tier will be a major milestone for the first Bay Area county to hit it.

“This is what the Blueprint was designed to do, to ensure a county moves forward only when we see a reliable trend of decreased transmission,” Marin County Public Health Officer Dr. Matt Willis said in a statement. “When a small uptick in cases is enough to keep us where we are, it’s a sign we’re not ready.”

Willis said as a result of the uptick in cases, the earliest Marin County could move into the Yellow Tier would be May 4.

The health officer said while 76% of county residents 16 and older have received at least one vaccine dose, it is too early to assume the county has reached community immunity and that vigilance is still needed.

“If people see relatively high community vaccination rates as a reason to let down their guard, they’re mistaken,” Willis said.

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Bungalow 44, a restaurant in downtown Mill Valley, is ready to embrace the change when the move to the Yellow Tier is finally announced.

“People are very excited. The last three weekends we’ve been extremely busy from 5 ‘o clock ’til close,” said manager Leslie Morgan.

San Francisco is the only Bay Area county to ever reach the Yellow, but it moved back to Purple when cases surged in November. If conditions continue to improve, San Francisco, San Mateo and Santa Clara counties could be in the Yellow Tier by May 4th.

Under the Yellow Tier, bars would be allowed to open indoors at 25% capacity. Breweries, movie theaters, places of worship and gyms are allowed to operate at 50% capacity. Indoor dining would remain unchanged at 50% capacity.

To date, nearly half of the residents in Marin County have been fully vaccinated. 73% have received at least one shot.

Under the Yellow Tier, outdoor gatherings would be capped at 100 people. Indoor gatherings are strongly discouraged, but would max out at 50 people.

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Governor Gavin Newsom has said he plans to do away with the tiered system entirely by June 15.