Health officials have released the first details about the mass vaccination strategy that aims to provide COVID-19 immunizations to about four million BC residents by September.

Beginning immediately, residents and staff of independent living centres, seniors' supportive housing facilities and those giving or receiving homecare support will be contacted to arrange appointments.

Seniors aged 90 and up will be eligible for a shot as early as next Monday, followed a week later by those aged 85 and over, while people over 80 can book starting March 22nd.

By mid-April, people between 60 and 79 and the medically vulnerable aged 16 and up can get their shots but must register for an appointment online.

BC is taking advantage of the strong immune response offered by the first dose of COVID-19 vaccine, and says it will nearly triple the time between the first and second shots to four months, up from the suggested 42 days.

Provincial health officer Dr. Bonnie Henry says first doses of the Pfizer-BioNTech and Moderna vaccines already offer what she calls "miraculous" protection of 90 per cent against the novel coronavirus.

She says increasing the time between the first and second doses of the vaccine will dramatically extend vaccine supplies, ensuring more people get their first shot.

Dr. Henry and Premier John Horgan made the announcement this morning and Dr. Henry says the National Advisory Committee on Immunization is expected to issue a statement soon, aligning with BC's decision.