Pfizer officials said in a report released Monday that they have new data showing their COVID-19 vaccine works for kids ages 5 to 11.

The Pfizer vaccine is already available for kids over the age of 12, but the drugmaker now wants to get its shot authorized for children between the ages of 5 and 11. The Associated Press reported Pfizer tested a lower dose of its vaccine among elementary school- and middle school-aged kids.

Pfizer says after getting the shot, kids showed the same levels of protection against COVID as teenagers and adults. With kids back in school and the highly contagious delta variant, pediatric infectious disease specialist Dr. Margaret Aldrich says this is good news.

Aldrich said she understands why parents might be hesitant about getting their kids the shot and encouraged them to talk to their child's doctor. The Pfizer vaccine is currently the only vaccine approved for people under the age of 18.

The changes come after the first full week of the school year in which nearly 900 classrooms, including those in charter schools, were fully or partially closed in the city’s 1,876 schools because of reports positive COVID-19 cases. One school entirely closed for 10 days after a cluster of cases.

The new rules take effect on Sept. 27. That day is also the deadline for the city’s public school teachers and staff to get at least their first shot of the COVID-19 vaccine under a city-wide schools mandate.