Philadelphia health officials have said for weeks that more than half of the city’s 5-to-11-year-olds have received at least one COVID-19 vaccine dose.

The city’s own data, though, suggest that the vaccination rate might be far lower, closer to a third in that age group. City officials said Friday they were looking at the numbers as part of a routine review, but declined to shed light on apparent discrepancies.

“It matters because we need to know how far we’re trying to achieve,” said Ala Stanford, the pediatric surgeon and founder of the Black Doctors COVID-19 Consortium who has had a focus on vaccinating schoolchildren. Accurate data “just helps me know what goal I’m going toward.”

Questions about the city’s reported vaccination rate arise just days before the city’s schoolchildren are slated to take their masks off in class.

The Philadelphia Department of Public Health reported on its online dashboard Friday that 44,040 Philadelphians ages 5 to 11 have had at least one vaccine dose since they became eligible to receive shots at the end of October. This meant, the web page states, that 53.6% of the age group had been vaccinated, a far better rate than in Pennsylvania, New Jersey, or the nation.

» READ MORE: Philly’s mask mandate ends, marking a step closer to normal but drawing mixed reactions

“We believe that our network of pediatricians that regularly offer pediatric vaccines and the parents that regularly get their children vaccinated contribute to getting as many children as we’ve seen get their COVID vaccine,” said James Garrow, a health department spokesperson.

But here’s where the discrepancy arises: Around 130,000 children ages 5-11 live in the city according to multiple sources, including the health department itself, which used this figure to report the vaccine rate in November.

So if you do the math: based on their figures, 44,040 children are only a third of about 130,000, about 20 percentage points lower than the city is reporting.

Asked about the discrepancy on Friday, city health officials said only that the data is under review. They would not confirm whether the 44,040 figure is accurate, or whether they were still using the same population figure as they had in November.

“Us putting out half-baked numbers that would likely change isn’t going to help any more,” Garrow said on Friday. “We’ve been working on this review and can comment on it when we’re done.”

Stanford said that between her organization, the city health department, Children’s Hospital of Philadelphia, pharmacies, and pediatricians’ offices offering children vaccines, 44,000 injections among kids ages 5 to 11 “seems reasonable with everybody pitching in, but it doesn’t give you 53% of children in that age group.”

Maintaining accurate data about most aspects of the pandemic has been a challenge for the past two years, with vaccination and case counts from the city, state, and Centers for Disease Control and Prevention all differing from time to time. Philadelphia acknowledged it took until January to include in the city’s vaccination rate data Philadelphians who received doses in other Pennsylvania counties. The Pennsylvania health department acknowleded in November its vaccination rates were wrong because many second doses were counted as first doses, inflating the number of partially vaccinated people. The number of fully vaccinated people was also inaccurately low.

Since Jan. 26, Philadelphia’s health department has touted a vaccination rate among 5- to 11-year-olds far greater than a third. Department director Cheryl Bettigole cited a steadily rising children’s vaccination rate at every news conference in February, saying on Feb. 16 the group’s rate was 53.1%. She did not mention the number at her most recent news conference Wednesday, when she announced the end of the city’s indoor mask mandate and said children would be able to remove masks in school after March 9.

Bettigole did cite the adult vaccination and booster rates, and then said, “and of course all the rest of the numbers are available on our vaccine dashboard,” which reports 44,040 kids ages 5-11, 53.6%, have had at least one shot.

Among the unanswered questions is whether the 5-to-11 vaccination rate was a factor in lifting the masking requirements in Philadelphia schools.

Philadelphia School District spokesperson Monica Lewis said the district has relied on city health department numbers since the start of the pandemic, and said their message that it’s safe to lift the mask mandate March 9 is “a recommendation that we’re taking close to heart,” even if the percentage is incorrect.

If health department officials are comfortable with city schoolchildren having the option to mask or not, “we absolutely believe that’s what we should be doing,” Lewis said.

» READ MORE: Philly teens greet COVID-19 vaccination efforts with interest and skepticism

Philadelphia Federation of Teachers president Jerry Jordan had already expressed concerns about ending the mask mandate March 9. Told about the possible data discrepancy Friday, Jordan said his concerns have not changed.

”It would be wise for the district to reevaluate entering into a ‘mask-optional’ phase until such time as vaccination rates amongst our students increase,” Jordan said in a statement, adding that the district and city should, “double down on efforts to promote vaccine access and accessibility for our young people.”

Stanford said the current COVID case counts in Philadelphia are so low there may not be greatly increased risk even if a far smaller percentage of children are vaccinated than is being reported. Still, she said, knowing an accurate vaccination rate does matter for masking policy, especially with children scheduled to take their masks off next week. It may be wise, she said, to “at least have somebody double check or triple check. It might make somebody say we’re going to push it back a week or a couple days.”

Staff members Jonathan Lai and John Duchneskie contributed to this story.