As the Centers for Disease Control and Prevention moved the Philadelphia collar counties into its high COVID-19 community level last week, a number of area districts announced plans to return to mask requirements.

A mere weekend later, however, some of those districts have reversed course to keep masking optional. And others aren’t embracing mandates, instead considering plans to recommend but not require masking.

The reasons for the walked-back announcements weren’t entirely clear. In Montgomery County, a number of school officials attributed their latest decisions to the county public health office. Yet, when asked what the county had communicated that prompted those reversals, a county spokesperson said Monday that the office’s guidance for K-12 schools “has not changed since it was released in March.”

This is how districts explained their decisions to their school communities:

In Lower Merion, after announcing Thursday that masks would be required the next day, the district backtracked later Friday, saying it had “received clarification that the CDC and (Montgomery County Office of Public Health) guidance strongly recommends, but does not require, indoor masking when the community is in the high level.”

The district’s superintendent, Khalid Mumin, also said Montgomery County had “expanded on the intent of their guidance,” noting a Friday news release from the county stating that “the CDC strongly recommends masking in all indoor public settings” when in the high level.

» READ MORE: School masking is back in a handful of Montco districts as county COVID level increases

On Saturday, the Upper Dublin School District also revised its plans to require masking, telling community members that while it had announced a mandate a day earlier, the county office of public health “has made it clear that it will continue to align its guidance with that of the CDC.” And by Sunday, the Cheltenham School District had informed parents that, after announcing three days earlier that a mask mandate was returning, its school board would hold a special meeting Tuesday to consider making masks strongly recommended rather than required.

“Since this past Thursday, and during this weekend, the Montgomery County Office of Public Health has made clear that it will align its expert guidance to that of the CDC,” Superintendent Brian Scriven said in the message. Days earlier, Scriven had told families that when the community is in the CDC’s high COVID-19 level, “per the recommendation of the Montgomery County Office of Public Health , masks are required indoors and on public transportation.”

Jessica Keene, Cheltenham’s director of student services, said Monday that the county hadn’t previously told schools that masking would be required when the COVID-19 community level was high, “but that it was a stance we could take as a district.”

After further conversation, Keene said, “we realized to stay in line with the CDC it would be better for us to transfer over to the highly recommended,” but not required approach.

Steve Yanni, superintendent of the Upper Dublin district, said Monday that the county’s office of public health had typically “been a little bit more conservative than other agencies,” with a more stringent approach to pandemic measures.

» READ MORE: Philly-area schools are making very different decisions after mask mandate was struck down

Now, “they’ve made it clear they are going to absolutely follow the CDC,” Yanni said. “So moving forward, I’m only looking at the CDC.”

Not all districts in the county that announced mask requirements last week are abandoning them: Norristown, for instance, started requiring masks Monday and “will evaluate week by week as the risk designation is updated by the CDC,” said Superintendent Christopher Dormer. And in Philadelphia — where the CDC updated the COVID-19 community level from low to medium last week — the school district also reinstated a mask requirement Monday.

The CDC’s metric is based on case rate, the rate of new hospital admissions for COVID-19, and the percentage of hospital beds in use by patients with COVID-19. The measure was unveiled in late February and at the time effectively downgraded the agency’s assessment of the severity of the pandemic across the region.

Many area schools — which were then deemed to be at a “medium” community level — dropped their mask requirements as a result. Now that the level has risen to high in Bucks, Montgomery, Chester, and Delaware Counties, some are taking action to revise their health and safety plans — though not necessarily to bring back masking.

In Chester County, the West Chester Area School District called a special school board meeting Monday night to consider a mask recommendation, but not requirement. (A message from the district in late February told parents that masking would be a choice when community COVID levels were low or medium, but did not mention what would happen at high levels.)

And in Delaware County, the Haverford Township School Board will meet Tuesday to consider dropping its requirement that masks return when COVID-19 cases reach 3% or more of a school building’s population for seven consecutive days. The district — which has hit that mark this month in two of its elementary schools, according to its dashboard — will vote instead on following the CDC’s recommendations, according to a message to families Friday.