City Council has abandoned its plan to return to in-person meetings next week for the first time since the coronavirus pandemic took hold in Philadelphia.

Citing the spread of the delta variant, Council President Darrell L. Clarke on Tuesday announced that lawmakers will continue meeting virtually when they return to weekly sessions after their summer break.

“It was my hope and expectation that Council would return to in-person Council sessions beginning this fall,” Clarke said in a memo to lawmakers. “Unfortunately, the very dangerous delta variant of COVID-19 has compelled many governments and businesses to reverse their plans for reopening. The delta variant represents an ongoing and unpredictable threat to public health, whether one is vaccinated or not.”

Case counts in Philadelphia began rising again in July, from 199 newly confirmed cases over the two-week period ending July 4 to 2,163 in the two weeks ending Aug. 29, according to city data.

The positivity rate of tests, however, has begun to decline, offering hope that the current virus surge will recede. In early August, more than 7% of tests were positive, while less than 4% were coming positive by the end of the month.

Clarke mandated on Aug. 10 that all Council members and staffers get vaccinated against the coronavirus before the fall session begins to allow in-person meetings to be conducted safely starting in mid-September. All 17 Council members have told The Inquirer they are fully vaccinated.

But in-person meetings also involve public comment, making it more difficult for Council to regulate who in the chambers is vaccinated.

» READ MORE: More people are getting COVID-19 tests around Philly as delta spreads and worry rises

Clarke’s memo Tuesday outlining the change did not give a timeline on how long the virtual meetings will go on, saying they will continue “at least for now.”

“As conditions develop, we will reconsider this decision, with the hope of returning to an in-person environment as soon as that makes sound medical sense,” Clarke wrote in the memo.

Clarke also announced Tuesday that the first meeting of the fall legislative session will be pushed back one day, from Thursday, Sept. 16, to Friday, Sept. 17, to avoid a conflict with Yom Kippur, the holiest day on the Jewish calendar.

Clarke made the change after Councilmember Allan Domb, who is Jewish, made a “heartfelt request” to avoid the conflict, the Council president said.

Council will resume holding its weekly meetings on Thursdays after next week.