The latest coronavirus numbers show that the bay area is moving in the right direction after the strong winter wave in California.
Positive test rates, along with cases, are on a clear downward trend across the region. These are key indicators the state uses to determine the placement of counties in its four-tier reopening system, with all nine counties in the Bay Area currently in the strictest purple tier after the recent lifting of regional blocks linked to the availability of ICUs .
Positive test rates help give authorities an image of how many people have the virus, including those without symptoms, and the possibility of a new outbreak of cases.
Based on the state’s most recent report on Tuesday for the week ending January 23, none of the positive test rates for the nine Bay Area counties were above 7.5%. It is a significant drop from the previous week, when four counties were over 8%. The rate is the seven-day average for all coronavirus tests performed that are positive.
“As long as we see the number of tests remain at a high level and remain at a high level … the fact that test rates are falling is an extremely positive finding,” said John Swartzberg, an infectious disease specialist at UC Berkeley. “We’ve seen this consistently across all counties here and the most affected parts of Los Angeles and San Diego. We are seeing this across the United States ”
Positive test rates are a factor that the state considers for county level assignments. It also takes into account two other metrics:
• Adjusted case rate: the seven-day average of daily coronavirus cases per 100,000 people adjusted for test levels.
• Health equity metrics: the rate of positive testing in the poorest neighborhoods in a county.
On January 26, Governor Gavin Newsom suspended home stay requests and most counties returned to the purple level, where outdoor dining and personal care services, such as salons, can reopen with limitations. The next level is red (substantial), followed by orange (moderate) and yellow (minimum), with more deals allowed to resume at each level with fewer changes.
All positive test rates recently reported for each Bay Area county are below the 8% limit for the purple layer. San Francisco was the lowest with 2.9%, Marin County followed with 3.4%, San Mateo with 4.4% and Santa Clara had a rate of 4.9% – all within the orange range for that metric .
But if the adjusted case rate and the positive test rate for a county fall to different levels, the county is assigned to the highest level. A county must stay on one level for at least three weeks before it can move to a less restrictive level, and to move forward, a county must meet the lower level metrics for the previous two consecutive weeks.
At the moment, adjusted case rates for all Bay Area counties are well above the red limit of 7 per 100,000 inhabitants. According to state data, San Francisco has the lowest rate of 12.5 new daily cases per 100,000, and Marin is double the purple limit at 14.7. Contra Costa has a rate of 29.3, while Solano’s is the highest with 32.6.
Swartzberg is concerned that with a current national average of 150,000 new cases daily, a lot of viruses are still circulating, and the worrying new variants that spread across the state and the bay area could create another strong outbreak when we don’t fully recover. of that one passed yet.
“What worries me is if we can get an increase at the top of our new baseline,” he said. “An increase of 150,000 cases a day, against 40,000 a day in November, imagine how bad that will be. We would be very close to having a collapsing health system. “
He said we need to “cut our case rates in half and in half again” to reach a much better baseline in the case of another increase in a month and a half to two months from now. Experts are concerned that the UK’s most contagious strain, which was recently identified in the bay area, will become the dominant strain in the United States in March.
Another measure of how widespread the coronavirus is within the community is the number of effective breeding, known as R-effective. It represents, on average, the number of people an infected person will infect and the rate of spread of the virus. If the R-effective is less than 1, the number of infected people will decrease. If it is greater than 1, the number of people infected will decrease.
On January 31, the R-effective for California was estimated at 0.78, which means that the spread of COVID-19 is likely to be slowing in the state. The most current figures for each county in the Bay Area range from 0.75 to 0.89, which again shows a slowdown.
“This is fabulous,” said Swartzberg. “This means that we will see a decrease in cases … We want to reduce R as far and as fast as we can, so those are encouraging numbers.”
The Super Bowl is coming this Sunday, and Swartzberg said he believed Newsom should have waited until after the game to suspend regional requests to stay home. Although he said that restarting outdoor dinners or reopening certain businesses will not make or break the curves of the falling coronavirus, he said it did not help the situation.
“What is going to do or break this is what people hear, not what the governor says,” said Swartzberg. “What people hear is, ‘Well, we’re not in shelter mode anymore, so we can go back and do things we used to do before, we don’t have to be so careful’, and that’s what scares me. “
He said people should remain vigilant with wearing masks and social detachment, and not change their behavior because things are looking better. And those who are immunized should continue with safety measures, because it is not yet known whether vaccinated people can still be infected or whether the new variants can escape vaccine antibodies or reinfect someone who has already fallen ill with COVID-19.
Kellie Hwang is a writer for the San Francisco Chronicle. Email: [email protected] Twitter: @KellieHwang