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In June, local public health officials decided that more than seven community outbreaks within a seven-day period would entitle them to take drastic action to shut down society. But now it is becoming clear the metric may not be a good indicator for the severity of the virus after all.
This story has been updated.
When is it safe to reopen society? Such a deceptively simple question – and yet one that has been made nearly incomprehensible by the government officials trying to answer it.
Officials have presented a dizzying assortment of metrics within these plans: number of new cases, number of hospitalizations, percentage of positive tests, doubling rate, cases per hundred thousand residents, number of community outbreaks and many others.
Within recent weeks, many of the metrics in San Diego County had been moving in the right direction. But even as the number of cases dropped, one metric remained stubbornly above its ordained threshold. For weeks now, San Diego has had more than seven community outbreaks of the coronavirus, within a seven-day period.
County officials characterize outbreaks as when three or more people from separate households, who tested positive for coronavirus, visited the same location over a 14-day period. (Voice of San Diego is suing San Diego County to get more data about these outbreaks.)
Back in early June, local public health officials decided that any more than seven outbreaks within a seven-day period is very bad. They decided if the number was above seven, it would entitle them to take drastic action to shut down society. San Diego Unified School District, the second largest district in the state, also adopted the metric. School officials said they would not reopen if the county was experiencing any more than seven outbreaks.
But now it is becoming clear the metric may not be a good indicator for the severity of the virus after all.
Public health officials came up with the number by looking at the first three months of outbreak data available to them back in June, said Dr. Wilma Wooten, the county’s chief public health officer. Now that more data is available – and the number of outbreaks has gone up – they think the number may need to be revised.
“We didn’t have a crystal ball,” Wooten said. “We have asked the state as well as some of our researchers locally that we work with on modeling to determine if there is a better number to use.”
The number of outbreaks may have looked artificially low back in the early months of the outbreak, because the county had so few contact tracers. Contact tracers work to contact everyone who has tested positive for coronavirus and everyone they have been in contact with. This helps identify the number of outbreaks. The county now has hundreds of contact tracers, which could mean that more outbreaks are being identified that might have previously gone unnoticed.
Despite the questionable significance of the seven community outbreaks threshold, it also plays an important role in whether San Diego Unified schools will reopen – at least on paper.
Back in August, schools were scrambling to come up with metrics that would help them decide when it might be safe to reopen. They had been receiving conflicting guidance from various state agencies. San Diego Unified officials convened a panel of experts from UC San Diego to advise them on when and how it might be safe to reopen.
Ultimately the panel of scientists and school officials decided to adopt several metrics created by San Diego County public health officials. On that list of metrics was the community outbreak trigger.
As of right now, every single metric adopted by the school system indicates schools are ready to open – except the community outbreak trigger. (While the metrics are currently below their mandated thresholds, several seem to be moving in the wrong direction since some local colleges have reopened their campuses and the county recently moved to open bars, restaurants and gyms.)
The district’s reopening metrics, however, require interpretation, said board vice president Richard Barrera. In other words, just because one metric has been tripped, it doesn’t mean schools can’t open. The metrics are meant to be evaluated in their totality, he said.
“We will keep working with the team from UCSD as we make decisions about when to move into subsequent phases of reopening,” he said.
Essentially, school officials will work to interpret the various metrics they’re tracking, while also getting feedback from the UCSD panel about whether they are interpreting the signs correctly, he said.
Barrera did acknowledge that public health experts may decide to change the community outbreaks threshold.
San Diego Unified’s decision-making and the metrics the district tracks can have a huge ripple effect. Most other districts around the county – and even others around the state – have followed the lead of both San Diego and Los Angeles Unified.
Kimberly Prather is a scientist at UCSD who is part of the team of experts advising San Diego Unified. She said she’s not encouraged by increasing COVID-19 cases over the past week. Until about 10 days ago, she said, she thought San Diego was very close to being able to begin a phased reopening of schools.
Prather said San Diego Unified has done lots of great work to prepare for reopening, including installing air filtration systems inside classrooms and preparing for students to spend as much time as possible outside.
She did acknowledge that the community outbreaks threshold may not be as dialed in as it should be. She also said that even though some of the other metrics may be under their current thresholds (like number of new cases), they are actually moving in the wrong direction.
Barrera said that very soon the district will start bringing students back to school. He said the district is looking to bring back roughly 12,000 elementary students who it believes to be some of the most vulnerable students in the district. This includes homeless students, special education students and some students who have been unreachable by their teachers.
News of that plan first emerged in late August. Initially, it seemed the phased reopening would begin any day. But in fact, the proposal still has not received final approval from the local teacher’s union. Barrera said a tentative agreement is now in place and the union’s board is set to vote on final approval of the plan later this week.
Correction: This story previously mischaracterized the definition of a community outbreak.