As anticipation continued to build for a planned partial reopening Friday, Mayor Jim Kenney on Wednesday cast some uncertainty about whether the city would delay its move to the yellow phase.

"I’m not going to say that officially,” Kenney said in response to questions about Philadelphia’s plan to move to yellow on Friday.

The numbers are “trending in that direction,” he said, but added that “we’ll have to see what happens today, tonight, tomorrow, Friday” with regard to crowds. Protests continued for the fifth day in Philadelphia, drawing masses of people — many of whom were not social distancing.

“I’m a little concerned, though, what might happen with 3-, 4-, 5,000 people close together without a mask for days on end," the mayor said.

The Philadelphia Department of Public Health reported Wednesday an additional 126 cases of COVID-19, for a total of 23,160, including 1,324 deaths.

Pennsylvania Secretary of Health Rachel Levine said Wednesday that the Health Department is keeping a close eye on developments in the Philadelphia region but that the city and its surrounding counties are still on track to move to the yellow reopening phase Friday.

“We’re comfortable with Southeast Pennsylvania,” Levine said.

Also Wednesday, Gov. Tom Wolf announced that he would allow the amended stay-at-home order to expire at 11:59 p.m. Thursday. The stay-at-home requirements were in effect only for counties still in the red phase.

Pennsylvania reported an additional 511 cases, for a cumulative total of 73,405, including 5,742 deaths. New Jersey added 523 cases, for a total of 162,068, of whom 11,880 have died.

“As phased reopening continues and all 67 counties are either in the yellow or green phase by Friday, we will no longer have a stay-at-home order in effect,” Wolf said. “I remind Pennsylvanians that yellow means caution, and even in the green phase everyone needs to take precautions to keep themselves and their communities healthy.”

In Chester County, plans to move to a yellow phase reopening have not been deterred by a slight uptick in cases.

“Everyone has to accept we are going to see some increases before we trend back down,” said Jeanne Casner, Chester County health director, who attributed the slight rise in cases to increased testing in the county and more people going out, but said she is not concerned.

Casner said she understands that people are eager to resume some of their normal activities but urged residents of Chester and Delaware Counties to continue practicing safety measures in public, including social distancing and wearing masks.

“Yellow is not open. Yellow still has a good number of restrictions — green, even, has restrictions,” she said.

As more parts of the state reopen, the Pennsylvania Health Department is ramping up its contact tracing program, in anticipation of a rise in the number of COVID-19 cases. Levine said her department is working with the Temple University College of Public Health to train 200 students as contact tracers for southeast and northeast Pennsylvania. Pennsylvania State College of Medicine students will assist with tracing efforts elsewhere in the state.

Temple plans to launch a 10-hour, self-guided online training program in mid-June. The program will eventually be open to the general public and could train up to 1,000 people by the end of the summer, said Resa Jones, chair of Temple’s department of epidemiology and biostatistics, who spearheaded creation of the new program.

The initial cohort of 200 students will participate in the tracing training as part of their degree coursework.

Contact tracing will be a key strategy in limiting community spread of the virus as people begin to resume their normal activities.

“COVID-19 is not behind us,” Levine said. “People need to stay vigilant that COVID-19 is still here.”

That was apparent in Philadelphia, where the law enforcement community mourned the death of a Philadelphia firefighter.

Eric Gore, 48, died Tuesday of COVID-19 at Temple University Hospital. Gore had served with the city’s Fire Department for nearly 24 years.

"He served with immense dedication, and we will forever honor him,” Police Commissioner Danielle Outlaw said.

In New Jersey, where the virus has hit nursing homes especially hard, Gov. Phil Murphy announced findings of an independent report to improve care in such facilities. Among the recommendations were paid sick leave and increased wages for staff, along with increased tracking of quality measures and greater penalties for those that fall short.

In research news, a large, randomized study of hydroxychloroquine — the drug that President Donald Trump touted as a “game changer” — suggests it cannot prevent infection with the coronavirus.

Previous studies of the drug, which is used primarily to treat rheumatoid arthritis and lupus, have suggested that it also does not help COVID-19 patients recover, but the evidence in either direction is murky. The World Health Organization suspended its trial of the drug amid concerns of side effects in May, then announced Wednesday it would resume, after physicians raised doubts about the data.

The new study, written by University of Minnesota researchers in the New England Journal of Medicine, tracked 821 adults who were exposed to COVID-19 from someone in the same household or through their jobs. Half took the drug for five days and half took a placebo.

After two weeks, 12% of those given hydroxychloroquine developed COVID-19, compared with 14% of those given the placebo — a difference that was not statistically significant.

Staff writers Laura McCrystal and Rob Tornoe contributed to this article.