VICTORIA -- People streaming into the Victoria Conference Centre Wednesday for a second COVID-19 vaccine shot all received Moderna for their second dose.

Many people on Vancouver Island and across the province got a Pfizer shot for their first dose, but a lack of supply of Pfizer – once dubbed the "workhorse" vaccine for B.C. – and a sudden surge of Moderna has led to a temporary shift, leaving Moderna as the vaccine being put in arms at most clinics right now.

Medical experts, including Dr. Gerald Evans, an infectious disease specialist at Queen’s University, say Pfizer and Moderna are effectively the same product, just created by different manufacturers.

"These are identical vaccines, they are using the identical template," said Evans Wednesday.

Still, Dr. Mike Benusic, who is in charge of mass vaccinations for Island Health, acknowledges that some people are getting upset when offered Moderna – with some refusing it and holding out hopes for a Pfizer shot later.

"There have been some isolated incidents of people choosing not to get their second dose at the clinic that day," said Benusic, emphasizing that the vast majority of people are accepting Moderna for their second shot.

He says the stress of the pandemic may be contributing to certain reactions, but there have been rare occasions when people get upset when their vaccine of choice isn’t offered at their mass vaccination clinic.

"There have been a few instances where people get angry if there brand is not available," said Benusic.

The bias for the Pfizer brand, despite both vaccines being deemed equally effective and safe to mix, comes down to branding, says Evans.

"This availability bias where, 'Wow, I just heard lots about Pfizer every time I read,'" said Evans. "Every time something is mentioned it’s Pfizer, and so people really get used to the idea, 'This must be the best vaccine, because I hear about it a lot.'"

Island Health encourages people to take either shot when offered. It says you are free to decline a Moderna shot and reschedule an appointment, but there’s no guarantee you'll get Pfizer the next time.