By CBSBoston.com Staff

BOSTON (CBS) — Trying to secure a coronavirus vaccine in Massachusetts? More appointments are rolling out online Thursday at two of the state’s mass vaccination sites.

Another 20,000 total new appointments will become available Thursday at Gillette Stadium and Fenway Park. At that time, eligible residents can click here to register for an appointment at those sites through CIC Health.

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Many older residents experienced frustrating issues and long delays as they tried to register on Wednesday, the first day that anyone over the age of 75 became eligible to sign up for vaccine appointments.

“Due to extremely high demand for appointments and limited vaccine supply, it may take time to secure an available appointment,” Gov. Charlie Baker’s administration said in a statement. “Residents are encouraged to keep checking the website as appointments are added on a rolling basis.”

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Find: Massachusetts Vaccine Sites

Fenway will start administering vaccines on Monday; Gillette has already been giving shots to those in Phase 1. The goal is for those mass vaccination sites to be injecting thousands of people per day as supply ramps up.

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The state is planning to have 165 vaccination sites up and running by mid-February. Visit Mass.Gov/CovidVaccine to find out when you’re eligible and to book an appointment.

CBSBoston.com Staff