KITCHENER -- People who received their first COVID-19 vaccine dose before May 9 in Waterloo Region and Wellington-Dufferin-Guelph will be able to get a second dose early, according to the Ministry of Health.

At a press conference on Thursday, officials with the province said the schedule change is due to concerns over spread of the Delta variant, the B.1.617 variant first identified in India.

Accelerated second doses appointments will also be available in Halton, Peel, Porcupine, Toronto and York.

As of Friday, there were 19 confirmed cases of the Delta variant in Waterloo Region, but health officials believe there are more based on current trends.

On Friday morning, regional officials said people can fill out an online form starting Monday to get an earlier second dose appointment.

The Wellington-Dufferin-Guelph health unit says their booking system will be ready by Monday morning, with second dose appointments depending on which vaccine was received as a first dose and when it was given.

"You'll only be able to get a second dose if it's been three weeks since Pfizer, four weeks since Moderna, or twelve weeks since AstraZeneca," said associate medical officer of health Dr. Matthew Tenenbaum.

Vaccine expert and professor at the University of Waterloo Kelly Grinrod said getting the second jab is essential amid the growing threat of the Delta variant.

"The first dose of the vaccine doesn't work as well as it did for the older variants, so we really need a second dose of the vaccine to protect you against the Delta Variant," she said.

Most of the AstraZeneca vaccines administered in Waterloo Region on or before May 9 were at local pharmacies. Grinrod says pharmacists are now overwhelmed with questions about second doses.

"Patients can't get through, they can't get any work done, they are having a hard time balancing the phone calls and vaccinating people," she said.

Grinrod recommends checking for information online instead of calling a pharmacy with questions.