Massachusetts health officials have submitted an initial order to the federal government to obtain doses of Pfizer's COVID-19 vaccine for kids as soon as its use is authorized. Secretary of Health and Human Services of Massachusetts Marylou Sudders said Thursday that the state estimates 515,000 children between the ages of 5 and 11 will become eligible for the vaccine once it gets the green light from federal authorities. She anticipates that will come during the first week of November."It's expected that Massachusetts will receive an initial allocation of 360,000 doses," she said.About half of those doses are going from the federal government to its pharmacy program and the rest would be ordered by MassDPH on behalf of other healthcare providers. "We surveyed our health care providers and 289 healthcare providers affirmatively responded," she said. "As a result of these, an order was submitted by the Department of Public Health today on behalf of the 289 providers."Needham pediatrician Dr. Alan Stern says most of his patients, and especially their parents, are eager for the vaccines to arrive. His practice needs to balance that demand with its regular patient load. "We conceivably could give 200-300 vaccines in a day," he said. The Pfizer vaccine requires two doses, spaced three weeks apart and a two-week wait for full protection to kick in, meaning kids who get their first shot of the two-dose Pfizer vaccine within a couple of weeks of the expected approval in early November will be fully vaccinated by Christmas.The country now has ample supplies of the Pfizer shot to vaccinate the roughly 28 million kids who will soon be eligible, White House officials said, and have been working for months to ensure widespread availability of shots once approved.Within hours of the formal approval, expected after the Food and Drug Administration signs off and a Centers for Disease Control and Prevention advisory panel meeting scheduled for Nov. 2-3, doses will begin shipping to providers across the country, along with smaller needles necessary for injecting young kids, and within days will be ready to go into the arms of kids on a wide scale.About 15 million doses will be shipped to providers across the country in the first week after approval, the White House said.Sudders estimated that 73% or 74% of kids 12 and older in Massachusetts have already been vaccinated.