VANCOUVER -- With the massive influx of Pfizer-BioNTech vaccine scheduled to start arriving in B.C. next week, health officials are now expecting to offer a shot to every adult in the province by mid-June.

B.C. is scheduled to receive 274,950 doses of Pfizer vaccine per week throughout the month of May, almost doubling the weekly deliveries of 138,060 doses received in April.

That will amount to more than a million shots of Pfizer alone next month, and shipments are expected to increase once again in June to more than 337,000 per week.

"That means that our age-based program will be accelerated and everybody will get their turn," provincial health officer Dr. Bonnie Henry said Thursday. "This is what we have to look forward to in the coming weeks."

With the size of vaccine deliveries B.C. is anticipating, Henry said "every adult in British Columbia will have access to vaccines by the middle of June."

That's despite Moderna being forced to dial back deliveries of its vaccine. B.C.'s only forecasted allocation of Moderna currently listed on the federal government's procurement website is for 135,600 doses in the week beginning on May 10. There are no forecasted deliveries of AstraZeneca.

Henry did note that British Columbia is expecting to receive its first shipment of Johnson & Johnson vaccine next week as well.

In the meantime, health officials are assessing the successes and failures of the pop-up vaccination clinics that were opened in the Lower Mainland this week in an attempt to offer protection to people living in COVID-19 hotspots.

Fraser Health's drop-in vaccine program saw people stuck waiting outside a handful of clinics for hours in the hopes of receiving a dose, sometimes unsuccessfully.

On the first day, some vaccine-hunters who weren't eligible for a shot were still able to obtain one. On the second, people lined up for hours at clinics that never opened.

On Thursday, Henry called the program a "new and innovative" approach to delivering vaccine, but acknowledged it had a rocky start.

"We admit there have been challenges with those clinics and those have been concerning," she said. "The good news is that thousands of people got doses of vaccine. But right now we need to regroup and determine how to best and most efficiently provide that vaccine to people in every community, but particularly in the communities where we know transmission rates are very high."

Henry said part of the purpose of the clinics was to get vaccine to people who haven't yet registered with the government for their turn. The province has been asking all B.C. adults to register on the Get Vaccinated website or by calling 1-833-838-2323.

Registering will mean people "will be able to receive the first available appointment," health officials said in a statement.

As of Thursday, B.C. has administered 1,749,375 doses of the Pfizer-BioNTech, Moderna and AstraZeneca vaccines. That includes 1,659,079 first doses – enough to protect about 32 per cent of the provincial population – and 90,296 second doses.