News Adults in Ontario who received a mRNA vaccine can book second dose as of Monday SHARE ON: Casey Kenny, staff Friday, Jun. 25th, 2021 (supplied by Pixabay) Those 18 and older in Ontario can get their second COVID-19 vaccine dose sooner. Starting at 8 a.m. Monday, all Ontarians aged 18 and over who received their first dose of Pfizer or Moderna will be eligible to book an appointment to receive their second ahead of schedule. Officials say it means approximately 1.5 million people will be able to get their second dose faster. Meanwhile, beginning at 8 o’clock Saturday morning, youth aged 12 to 17 who live in a Delta hot spot are eligible to book their second dose appointment. They can make their appointments through the provincial booking system, directly through public health units that use their own booking system, and through participating pharmacies.