The daily average of new coronavirus cases across a large swath of the Baton Rouge area fell by two-thirds in the 1½ months since Gov. John Bel Edwards imposed a statewide mask mandate and closed bars.

Susan Hassig, a Tulane University epidemiologist, said that means if cases do bump back up after the Labor Day break and after other loosening of restrictions, including the continued growth of in-person classes, any new growth in cases will begin from a higher starting point than in March.

She said hospital officials in the Baton Rouge area remain "very, very worried" about their ability to handle new cases because of tight capacity.

"It is real, and the ramifications of people easing up or kicking back on guidance or mandates is terrifying to them," Hassig said Friday. 

Edwards said Friday that he was hopeful that cases will have declined enough statewide that he can announce later this week that social distancing restrictions can be loosened from Phase 2 to Phase 3. The governor has faced criticism from business groups and some conservative leaders that he has waited too long to reopen the state further and ease the financial pain of an economy restrained by public health measures.

Trends for rolling case averages and percent positivity have continued to move more consistently downward statewide than for the portion of the Baton Rouge area in state Health Department's Region 2 in recent weeks, state dashboard data show.

State officials and some health experts said the sharp and consistent drop in new cases between mid-July and mid-August — as calculated on a rolling, seven-day average — had showed the mask and bar measures were, to some degree, strongly correlated with the drop in cases. A delayed but apparent effect on reduced hospitalizations statewide only furthered that conclusion, some experts added.  

"It's clear that after the governor put the mask mandate in place that we began to see a decline in cases, along with decreases in hospitalizations and COVID-like illnesses," Kevin Litten, a state department of health spokesman, said in late August. "It generally takes about a week if not two to begin seeing the impact of events or decisions on COVID-19 indicators, but it can be seen in the dashboard graphs."

Since mask mandate and re-closure of bars, coronavirus cases in metro Baton Rouge have dropped

Even then, though, some officials said late last month that they remained worried about underlying trends in the Baton Rouge area, including lingering high percent positivity, or the rate of positive cases for a given batch of tests. The measure is seen as one possible signal of the depth of infection in the community and a marker of testing strength.

"Masks have had a tremendous effect, and we're very thankful for our patients and for the community that the mask mandate occurred, but it hasn't had enough of an effect, and I remain very concerned about Region 2's percent positivity," Dr. Catherine O'Neal said in late August.

O'Neal is an infectious disease expert and chief medical officer at Our Lady of the Lake Regional Medical Center in Baton Rouge.

Since her comments, Region 2's overall positivity rate continued to go up to around 13.4% through Aug. 28, as testing has slowed down significantly from highs in July during a federal effort to boost testing. Hurricane Laura has also disrupted some testing. 

The Region 2 area encompasses Ascension, East Baton Rouge, East Feliciana, Iberville, Pointe Coupee, West Baton Rouge and West Feliciana parishes.

But a parish-by-parish analysis within Region 2 and across the rest of the Baton Rouge area offers a more mixed picture of percent positivity.

East Baton Rouge, Ascension, Livingston and other parishes have seen their positivity rates drop in recent weeks, while some outlying parishes with large state-run facilities where cases have sharply increased, including East and West Feliciana parishes, have seen their positivity rise.

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At the same time, bed and intensive care unit space in the Baton Rouge region remains tight, state data show, though some of that may be attributed to Hurricane Laura's devastation of Lake Charles hospitals. 

Since those conclusions about the mask mandates were reached in late August, the steady fall in cases has stalled out or even rebounded a bit in the Baton Rouge area, according to state data and an Advocate analysis.

During the same period, schools reopened, some with at least a hybrid of virtual and in-person classes.

East Baton Rouge, Livingston and Ascension Parishes have had students and staff get infected, forcing quarantines, though the numbers remain tiny relative to the size of the systems.

Ascension, for example, has had 46 positive cases since mid-July in a system of more than 23,000 students and 3,000 employees, but those cases have led to quarantines among some students and staff at 20 different schools. Only 15 cases remain active, a system spokeswoman said.

More than 150 students and staff in Livingston public schools were quarantined two weeks ago but that number has dropped significantly since then.

East Baton Rouge Parish schools have had a handful of cases but is planning to start in-person classes among younger students later this month. LSU has also had recent batches of positive cases.

"The educational process, especially in when it involves in-person teaching and on campus residency and everything else, is going to bring people into contact with each other in ways that they haven't been for a very long time," Hassig said. "And so it would be totally expected that cases would change and, likely, potentially, not in the way we would want them to go." 


Email David J. Mitchell at dmitchell@theadvocate.com

Follow David J. Mitchell on Twitter, @NewsieDave.