Debate rages over vaccine protocol

B.C. to delay giving second doses so more people can get initial shot

Scientists around the world are debating whether it's the right choice to hold off giving a second coronavirus vaccine dose in order to give the shot to more people more quickly.

British Columbia, along with jurisdictions such as the U.K. and Denmark, have decided to hold off giving a second vaccine dose for beyond the period recommended by vaccine makers. Germany is considering a similar move.

In B.C., the idea is that by holding off giving some people a second dose to 35 days, up from 21 days for the Pfizer-BioNTech vaccine and up from 28 days for the Moderna vaccine, an estimated additional 150,000 people will get a first dose by the end of March, given the limited supply expected during the period.

In the U.K., health officials have decided to put off giving a second dose for up to 12 weeks, in Denmark up to six weeks. These controversial vaccine dose decisions are being made as the virus' rapid winter spread in the Northern Hemisphere continues and with the advent of a virus variant that spreads more quickly.

Dr. Bonnie Henry, B.C.'s provincial health officer, defended the decision to extend second doses to 35 days, saying it had been taken in consultation with clinical and immunization experts in B.C. The decision included an ethical review, an examination of the vaccine data, modelling of how many people could best be protected, and how much and when vaccine is expected to arrive, she said.

“Absolutely the science bears out that this is a reasonable approach that maximizes our ability to protect more people during this, the most infectious period, where we have the highest rates of transmission,” Henry said during a briefing on Thursday.

The periods between doses are established in the trials of each company's vaccine. The first dose introduces an element of the virus that creates an immune response in the body that teaches it to fight off the virus. The second dose helps increase protection against the virus.

Pfizer and BioNTech warned this week that there's no data to demonstrate that protection after only a single dose is sustained after 21 days.

Leading global health authorities such as Dr. Anthony Fauci, who has been the director of the National Institute of Allergy and Infectious Diseases in the U.S. since 1984, has spoken out against extending the period for second doses.

The World Health Organization and the U.S. Food and Drug Administration also warned this week against deviating from the prescribed dose schedules.

In Canada, the country's chief public health officer, Dr. Theresa

Tam, has asked the National Advisory Committee on Immunization to investigate whether it would be warranted to delay the second doses of a COVID-19 vaccine in a bid to get first doses to more people faster.

“This is a topic of, of course, active discussion,” Tam said this week.

She noted the situation is grim in Canada, with more than 7,500 new patients diagnosed every day, more than 77,700 people currently infected with the virus, and more than 4,000 infected people in the nation's hospitals.

Over the last week, an average of 122 Canadians have died of COVID-19 every day.

In B.C., daily reported cases climbed to 761 on Thursday and another eight people were reported dead. More than 41,000 people have been inoculated in B.C., most of those residents and workers at long-term care homes.

Horacio Bach, an infectious disease expert at the University of B.C., said he's opposed to extending the second dose beyond that recommended by the trials.

“The reason is, we don't know what would happen if we delay. Maybe it's not a big deal, but we don't know that,” said Bach, an adjunct professor in the division of infectious diseases at UBC's faculty of medicine.

The British Medical Journal published an article this week that noted there's not much evidence to support changing vaccine dose schedules for the Pfizer-BioNTech vaccine as trials didn't compare different dose spacing.