HOUSTON, Jan. 4 (Xinhua) -- The Health Department in the U.S. city of Houston on Monday launched online registration allowing people at the highest risk of coronavirus disease to schedule appointments to receive free COVID-19 vaccinations.

According to a press release, people aged 65 and older and people aged 18 and older with at least one chronic medical condition putting them at increased risk of severe illness and death may sign up online to get the vaccine. These groups are prioritized as Phase 1B of the state of Texas' vaccine distribution plan.

Frontlines healthcare workers who have yet to receive the vaccine also are eligible to sign up to get the shot through the health department, the release said. Healthcare workers are grouped as part of Phase 1A distribution.

Before the online site was launched, appointments have been available through the city's health department's COVID-19 call center.

"The new online registration, in addition to the call center, will make the process more efficient. While there is great public demand for the COVID-19 vaccine, there is also a lot of hesitancy. I understand the concerns, but I encourage all eligible Houstonians to get vaccinated to help stop the spread of the deadly virus," said Houston Mayor Sylvester Turner.

As additional doses become more plentiful in the coming weeks and months, the department will ramp up local vaccination efforts and announce other free vaccination opportunities.