Ontarians between 18 and 59 started booking fourth COVID-19 vaccine doses on Thursday morning as the province expanded access to all adults amid a seventh wave of infections.

The provincial booking site began allowing any adult who had their first booster at least five months ago to book another shot as of 8 a.m. Appointments were also available through pharmacies and public health units that have their own booking systems.

Some residents were eager to book right away.

Emily Clark, a public health worker in Hamilton, was able to book appointments for herself and her husband, securing shots for next week.

“It was no big deal,” said Clark, who has elderly family members and an unvaccinated four-year-old.

“We've been fortunate enough to avoid (COVID-19) so far, we really just want to make sure that we're as protected as we can be.”

But not everyone's experience was smooth.

Sarah Ojamae, a freelance content writer living in west Toronto, said she tried to book an appointment at 8 a.m. on Thursday, but she ran into issues with the booking portal.

Ojamae, 45, said the portal repeatedly told her she was ineligible to book a fourth dose after answering a number of screening questions.

“I haven't had COVID, as a freelancer I live in terror of having it,” she said. Ojamae got her third dose in December 2021 and said she fears that potential long-term effects of a COVID-19 infection would put her livelihood at risk.

Others who had difficulties booking through the portal said they were eventually able to snag appointments at pharmacies or through other channels.

Previously, second boosters - or fourth doses - were only available to immunocompromised people, those aged 60 and older, and Indigenous adults.

Chief Medical Officer of Health Dr. Kieran Moore announced the expanded eligibility on Wednesday, but has signalled that young people who don't have underlying health conditions may choose to wait for the fall, when it's hoped that vaccines specifically targeting the Omicron variant will become available.

He has said that Ontarians should speak with their health-care provider about whether a fourth dose is right for them.

Moore also said it's recommended that people wait at least three months after a COVID-19 infection to get a booster shot.