VANCOUVER -- A team of B.C. doctors, researchers and clinicians is urging the provincial government to reconsider its vaccination strategy for the elderly after they found seniors aren’t developing enough antibodies to COVID-19 after one dose of the Pfizer vaccine – a recommendation that’s become more urgent with the expansion of visitation to care homes.

A preprint published Wednesday by 20 experts from University of British Columbia, Simon Fraser University, the BC Centre for Excellence in HIV/AIDS and St. Paul’s Hospital found that seniors with a median age of 82 produced lower levels of COVID-19 antibodies, and the ones they did produce weren’t as good at blocking the virus.

They concluded: “We recommend that second doses not be delayed in elderly individuals.”

“In general, extending the dosing interval is a good idea because the second dose, when it’s a bit further from the first dose, is more powerful, but that’s not necessarily the case in older people,” explained study co-author and St. Paul’s Hospital medical microbiology and virology leader, Dr. Marc Romney. “The message to extend the interval might need to be nuanced a bit based on the population – we know in long-term care, people are surrounded by a highly-vaccinated population of healthcare workers, but older people in the community are not.”

The researchers tested a dozen care home residents who’d never had COVID, as well as 18 health-care workers who’d never had the virus, plus four who had to find out if delaying the second dose beyond Pfizer’s recommended three-week gap would have an impact.

Top doctor downplays findings

Provincial health officer Dr. Bonnie Henry was lukewarm to the findings.

“We'll be continuing to watch and if we start to see a decrease in protection, in real-world protection and vaccine effectiveness in elderly people, then we will speed up second doses for that group of people,” she said, pointing out it’s a small study. “Looking at antibodies in 18 people doesn't change our management, when we have other studies that have shown us that there is still a very high level of protection, overall.”

She said the fact there has only been a handful of care home outbreaks since widespread vaccination began is proof the strategy works, and she emphasized no one had died.

But the researchers argued those recent outbreaks “underscore the continuing vulnerability of elderly adults to SARS-CoV-2 infection, even after vaccination.”

On March 1, the provincial health officer announced that the second dose for everyone would be delayed from the previous 42-day interval to four months. While many doctors and citizens alike have raised questions about the change in the manufacturer’s suggested process, Henry has pointed to the endorsement from the National Advisory Committee on Immunization and insisted it’s better to have some protection for more people than maximum protection for a few.

There are signs NACI may amend its guidance since it approved the long gap between shots when vaccine supply was scarce; in the past week, there has been a glut.

On Monday, the country’s chief science advisor urged provincial health officials to change their policy on this basis.

"I think the one-size-fits-all approach needs to be really modulated in terms of who we need to be protecting,” said Dr. Mona Nemers. “If we don't have supply issues we should go back and stick to the original NACI recommendations and that's six weeks, because that’s what was tested.”

The country’s deputy medical health officer hinted there could be a change in direction soon.

“NACI is in the process right now actively looking at new evidence to look at certain sub-populations as you mentioned, maybe seniors and and others with immunocompromised conditions,” said Dr. Howard Njoo. “NACI, we anticipate, will be coming forward with new recommendations, maybe, in that regard.”

There are 236,341 British Columbians over the age of 80. Only 87,180 people have received their second dose, among them health and care home workers.

New research for Canada, but established internationally

The joint study is the first of its kind in Canada. It is a preprint, which means it hasn’t been peer-reviewed yet.

“Using a range of immunoassays, we observed significantly lower antibody responses to SARSCoV-2 following one dose of BNT162b2 mRNA vaccine among 12 residents of (long-term care) facilities compared to 18 (health-care workers),” the authors wrote. “In contrast, and consistent with prior studies highly elevated antibody responses were seen in four convalescent (health-care workers) after one dose of vaccine.”

While Henry downplayed the small sample size of the study, Romney pointed out it’s supported by similar international studies that came to the same conclusions.

“It’s consistent with this phenomenon known as immunosenescence, so I don’t think we should dismiss these findings. I think they need to be considered more globally with a reasonable approach,” he said.

He also pointed out variants are surging in the province, and with some of them evading vaccinations, it’s more important than ever to fully vaccinate those most at risk.

“So absolutely it’s urgent if they’re opening up visitation to long-term care facilities. I think it’s a good idea that visitors be allowed because it’s all about quality of life, the question is: How can it be done safely?” he asked. “There’s issues of vaccine, there’s issues of rapid testing, these are all important interventions to protect these vulnerable people – keeping in mind, older vulnerable people and their families have borne the brunt of the pandemic, and so our response should be proportional.”