About three months after COVID-19 vaccines became available to children aged 5 to 11, only about 51% have received their first dose, according to the latest data from the Massachusetts Department of Public Health.That’s higher than the nationwide rate of 31% for the same young age group but far lower than all other age categories in Massachusetts or nationwide. “This is a disease that can really hurt people, it’s a disease that even in healthy children can sometimes cause significant disease,” said Dr. Richard Malley, an infectious disease specialist at Boston Children’s Hospital. Malley said a lag in vaccination rates among younger children doesn’t surprise him. He’s met many parents who have doubts about vaccinating their children, even if the parents are themselves vaccinated. “They’re not sure that the risk, the theoretical risks, of the vaccine are making them as comfortable given the fact that they also understand that the children themselves are not at a huge risk of significant COVID disease,” Malley said. “That group has been a lot harder to reach.”Malley says parents have a variety of individualized concerns and he says it’s important for physicians to talk them through. He said data shows the risk of side effects is very rare and easily outweighed by the benefits of vaccination. “By vaccinating a young child, you are protecting them and you are also providing additional layers of protection for other individuals in the family who might be significantly older, or maybe immunocompromised, maybe have some risk factors,” Malley said.