Martha’s Vineyard Hospital is starting its rollout for booster shots of the Pfizer vaccine, opening sign-ups for a small number of doses Friday evening.

According to head of hospital operations Claire Seguin, people 65 and older who received their second dose of the Pfizer vaccine six months ago — April 1 or earlier — are eligible for signups. People who have underlying medical conditions, or who live or work in a high-risk setting, are also eligible.

A list of high risk settings and conditions is available on the CDC’s website. (https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-...)

The hospital will make 156 booster shot appointments available at 5 p.m. Friday. Appointments will be available for Tuesday, Oct. 5, Wednesday, Oct. 6, from 11 a.m. to 4:30 p.m., and Friday, Oct. 8, from 1:30 p.m. to 3:30 p.m.

Signups are available on the hospital website, or by going to the URL https://covidvaccine.massgeneralbrigham.org/.

The FDA has not yet authorized the Moderna and Johnson & Johnson vaccines for booster shots.

Ms. Seguin said state officials would likely make more booster shots available next week.

“More vaccine boosters will come, but this is how the process will begin,” Ms. Seguin said. “This is a walk, don’t run situation, to get your booster.”

The hospital has already administered close to 200 third-dose vaccines to immunocompromised people.

Although they represent the same, full-dose shot, the medical community uses the term third-dose to refer to shots for immunocompromised people, while the term booster shot is being used for the general population who use their third shot to boost virus immunity.

Ms. Seguin said a booster shot is currently recommended for all eligible people who received their second Pfizer vaccine six months ago, although she said there was not reason for concern.

“Eventually, all of us will need a booster shot to the Pfizer vaccine, which is what we know,” Ms. Seguin said. “But it’s not something that you have to do urgently. We’re all protected right now.”

Meanwhile, the hospital is continuing its first and second-dose vaccine program, with 235 first and second dose appointments scheduled for the upcoming week.

There are no patients currently hospitalized with the virus.