When will people be able to get the COVID-19 vaccine, and how will they know?

Louis Dartigue, a nurse at Life Care of Acton, got his shot a couple of weeks ago. Phase 1 in Massachusetts prioritizes health care workers.Suzanne Kreiter/Globe staff

The slow rollout of coronavirus vaccines has raised a host of questions about how state residents will know when it’s their turn to be immunized. With limited vaccines available and fewer shots being administered than promised, the Globe asked Dr. Paul Biddinger, medical director for emergency preparedness at Massachusetts General Brigham and chair of the state’s COVID-19 vaccine advisory group, to explain what residents should expect in the coming weeks and months.

When will people know it’s their turn to get the vaccine?

Biddinger referred to a state website that officials frequently update with the status of different phases of the vaccine rollout. Phase 1, which is ongoing, prioritizes health care workers, those living in long-term care facilities, and first responders. Phase 2, which is slated to begin in February, focuses initially on individuals 75 and older and younger people with at least two or more medical conditions that put them at elevated risk of severe illness from COVID-19. It later includes those 65 and older. The general public will be immunized in Phase 3, slated to begin in April.

“Many physicians’ practices are also building mechanisms to inform patients when they become eligible, either through e-mail, texts, or phone calls,” he said. “Everyone understands that it’s not reasonable to expect people to continually monitor the website, so local and state leaders are also discussing other communications strategies to make sure people are aware.”

What about people who don’t have a primary care physician?

Biddinger said commercial pharmacies will be administering vaccines, and residents should seek information about their eligibility for the vaccine from local public health departments.

“We believe there will be several large-scale vaccination clinics set up, in places like conference spaces, gyms, or armories. Fenway Park, Gillette Stadium, and other large areas have been mentioned as well and are being looked at,” he said. “If a resident doesn’t have a primary care physician, they’ll need to look at state messaging, the state’s website, and the media to know when they are eligible for vaccination.”

Will residents have to make an appointment with their doctor, clinic, or pharmacy to get vaccinated?

In most cases, they likely will, he said. That’s because there’s a mandatory 15-minute waiting period after someone gets the vaccine, so medical staff can observe if they have an adverse reaction. Appointments also reduce the need for waiting spaces.

“There could be real queuing problems if everyone came at the same time, and we want to avoid long lines for physical distancing,” he said. “There may be some walk-in options, but, for the most part, people will need to schedule an appointment.”

At the end of a given day, there may be extra doses of vaccine, because some might not show up for their appointments. So some clinics may make last-minute contingency plans for the end of the day so doses aren’t wasted. Vaccines must be used within six hours once a vial has been punctured. The vials have five doses in them.

When should residents contact their doctors about getting the vaccine? Is this something they should do soon?

Physicians’ offices are not scheduling vaccinations now, because Massachusetts remains in the first phase of its plan, limiting vaccines to first responders, nursing home residents, and others considered “critical” personnel. “When the state announces that it is moving into Phase 2 or 3, patients who believe that they are eligible should contact their doctors, if they have not already received outreach from those practices,” Biddinger said.

He said the state has plans for drive-through vaccination locations and other mass vaccination sites.

“No one in the state wants to have vaccination vials sitting on shelves, so efforts are focused on administering the vaccine as soon as it arrives to those eligible,” he said. “Everyone wants to vaccinate the public as quickly as we have supply, so we can move into the next phases.”

Who determines if a resident has sufficient “comorbidities,” such as heart conditions and obesity, to make them eligible to receive the vaccine in the second phase?

“The medical systems are searching medical records to help identify patients with those comorbidities, hopefully making it easier to identify eligible patients,” he said. People are unlikely to have to show evidence they have a comorbidity, he said. “Obviously, it’s really important for patients and for systems to honestly follow the rules,” he said. “More information on how this will be assured is likely to come soon.”

Will residents have a choice of vaccines?

Probably not, given how limited the supply remains. “There’s so much complexity in administering, there’s no real option to provide a choice at this point,” he said. Biddinger said he wouldn’t have a preference between the two. “They’re equally effective and equally safe,” he said. “There are only limited differences.”

The Moderna vaccine, for example, is approved for those age 18 and older, while the Pfizer vaccine is for those ages 16 and up. There are also rare allergies associated with each that may affect a small number of people.

Other vaccines, if approved, could increase supply and potentially give residents more of a choice.

When will children be eligible for the vaccine?

It will be at least several months, as clinical trials must be conducted before federal regulators would sanction the vaccines use in children, he said. The trials have to enroll large numbers of young patients. Pfizer and Moderna started testing the vaccine in children ages 12 and older in November and December.

“I expect it won’t be until late spring before children could be eligible, at the earliest,” Biddinger said. “For younger children, it’s unclear when they will be eligible.”

Will those who get an initial dose be assured of getting the second dose?

As soon as a dose is administered, the second dose is automatically assigned to that person, he said. They will be scheduled to receive their second doses while getting their first dose. Doses, however, aren’t left on a shelf for them, they’re automatically ordered and accounted for later when they’re needed. “That’s the way it has happened so far, and we’ve been receiving our second doses, as promised,” he said.

As of Thursday, the federal government had shipped more than 21 million vaccine doses, but only 5.9 million people had received a dose. On Friday, President-elect Joe Biden’s transition team said his administration plans to release nearly all available doses “to ensure the Americans who need it most get it as soon as possible.” Biden has promised to administer 100 million doses by his 100th day in office.

How long will the vaccines provide immunity?

“There are hints that we’ll have durable immunity for at least three months, but at this point, because we don’t have the data yet, there’s no way to say whether it’s a year or longer,” he said.

When will the average person expect to get a vaccine?

Biddinger said the timing still looks like April for when most people will be eligible. That depends on the stability of the supply chain and assumes that at least one or two other vaccines also receive emergency approval from federal regulators. “There’s so much unknown that we cannot predict this with certainty,” he said.