Hundreds of thousands of Massachusetts children are now eligible for COVID-19 vaccination as many of their parents and older relatives are also eligible for booster shots. Kid-sized doses of the Pfizer-BioNTech vaccine recently gained federal authorization, making the jab available to children between the ages of 5 and 11. The federal government promised enough doses to protect the nation’s 28 million children in the age group. Secretary of Health and Human Services of Massachusetts Marylou Sudders said the number of newly-eligible children is about 515,000.Cambridge-based Moderna is also pursuing authorization to administer its vaccine to adolescents and kids, but additional research on the 12-17 age group is slowing that process. Meanwhile, booster shots of the Pfizer, Moderna and Johnson & Johnson vaccines are also available for millions of adults who already completed their initial vaccine course.Are you eligible for a booster shot? Find vaccination appointments in MassachusettsThose who received Pfizer or Moderna shots first, are eligible for booster shots if your last dose was at least six months ago and you’re 65 or older, or are a younger adult who has health problems or a job or living conditions that put you at higher risk of severe illness or exposure to the coronavirus. Health care workers, for example, are included because they are regularly exposed to the virus and can’t come to work with even the mildest of infections.Anyone who got a J&J shot at least two months ago is eligible, regardless of age or other factors. The different rule is because the J&J vaccine was found to be less effective than two doses of the Moderna or Pfizer formulas, and health authorities decided it was important for the J&J recipients to achieve a similar level of protection. As for the timing, J&J simply tested more people with a two-month booster than one at six months.For recipients of Moderna or Pfizer vaccinations, there’s no clear data that everybody needs another dose, but immunity against infection in at least some people appeared to wane around six months.The Centers for Disease Control and Prevention and Food and Drug Administration didn’t recommend that people switch vaccine brands but left open the option. Preliminary results of a government study found an extra dose of any vaccine triggered a boost of virus-fighting antibodies regardless of what shots people got to begin with. For people who originally got a J&J vaccination, the Moderna and Pfizer shots appeared to offer a stronger boost. But researchers cautioned the study was too small to say one combination is better than another.BREAKTHROUGH CASES IN MASSACHUSETTSMassachusetts public health officials track the number of COVID-19 cases among people who’ve been fully vaccinated against the virus. These are often called “breakthrough” cases and their rise in the face of the contagious delta variant has contributed to interest in the idea of booster shots. Breakthrough infections can cause disease with symptoms, and some people can have no symptoms at all. Research has shown that if people become infected after vaccination, typically they get a milder case.Officials began to publish data about breakthrough cases routinely during August. RATE OF COMMUNITY TRANSMISSIONThe U.S. Centers for Disease Control and Prevention has created a four-tier system to indicate the rate of transmission of COVID-19 in every county.Blue = LowYellow = ModerateOrange = SubstantialRed = HighCOVID-19 VACCINATION DATAAnyone age 5 or older who lives, works or studies in Massachusetts is eligible to be vaccinated. MASSACHUSETTS CORONAVIRUS CASESSymptoms reported for patients with COVID-19 have included mild to severe respiratory illness with fever, cough, and difficulty breathing, as well as new loss of taste or smell. Further details are available here.This state website will help you locate the nearest COVID-19 testing facility. Massachusetts also has an online resource that allows you to assess your symptoms and find the right care.For more information on coronavirus and testing, you can also call 211, which is a 24-hour state-supported hotline.MASSACHUSETTS HOSPITALIZATIONSIf you develop emergency warning signs for COVID-19 get medical attention immediately, the CDC said.Emergency warning signs include:Trouble breathingPersistent pain or pressure in the chestNew confusion or inability to arouseBluish lips or face*This list is not all-inclusive. Please consult your medical provider for any other symptoms that are severe or concerningMASSACHUSETTS FATALITIES