NEW HAVEN, Conn. (WTNH) — Starting March 19, Connecticut residents 45 and older can register for the COVID-19 vaccine. That alone is making state officials brace for a new wave of registrations.

RELATED: Healthcare systems prepare to ramp up sign-ups and vaccinations to those 45 and over

Around 400,000 residents will now be in the eligibility pool, in addition to the residents 55 and older, as well as healthcare workers, nursing home residents, educators, responders and people 65 and older who are already eligible.

People 16 and older will be eligible to register starting April 1.

“There’s a blend here as we move from age group to age group,” said Governor Ned Lamont. “In some of our communities two thirds of the people, 55-64 have been vaccinated. In others maybe it’s just a third in some of our cities, and we want to make sure there’s no vaccine left on the shelf. That’s why we’ve moved into the next age category tomorrow.”

“We know that there is a certain threshold, usually at about 50% of a certain age group being vaccinated where we start seeing that demand and supply change start to happen,” Dr. Manisha Juthani, Yale Medicine Infectious Disease. “And I believe that’s exactly what we’ve seen in the state, which is why they are able to open it up to 45 and older starting tomorrow. So, this is great news for our state.”

Dr. Andrew Ko, Dept. Chair of Epidemiology and Infectious Diseases at Yale School of Medicine added, “This has far exceeded my expectations that 80% of the population over 75 would be vaccinated at this point. It seems that we’re on track for all the other age groups that are following to reach that goal of 80%. Now, the initial vaccine is free, but most places will bill you for an administrative cost covered by most insurance plans.”

Here are a list of ways you can register for the COVID vaccine:

With past COVID vaccine eligibility waves, residents saw issues with accessing sign-up pages and getting an appointment. The best thing residents were told to do is be patient and keep trying. State officials ask residents to only sign up for one vaccination appointment.

People can get their doses at different places, as long as they get both doses from the same manufacturer. Pfizer, Moderna, and Johnson & Johnson are all proven to be safe and effective. Pfizer and Moderna require two doses, while J&J is only one dose.

The CT Vaccine Hotline is now in service from 8 a.m. to 8 p.m., seven days a week. Call (877) 918-2224 for assistance with making an appointment to get the COVID-19 vaccine.