Jeanne Hennebury, 93, receives the Pfizer-BioNTech COVID-19 mRNA vaccine from Vena Anderson at a pharmacy prototype clinic in Halifax on Tuesday, March 9, 2021. CANADIAN PRESS/Andrew Vaughan

Jeanne Hennebury, 93, receives the Pfizer-BioNTech COVID-19 mRNA vaccine from Vena Anderson at a pharmacy prototype clinic in Halifax on Tuesday, March 9, 2021. CANADIAN PRESS/Andrew Vaughan

Research raises questions over delayed second vaccine doses for seniors

A Vancouver study found long-term care residents had a weaker immune response to their first dose of the Pfizer-BioNTech vaccine than younger healthy adults

More questions are being raised about how long second shots of the COVID-19 vaccine can be delayed for seniors and other immunocompromised people.

The federal body that advises how vaccines are deployed said Thursday it’s reviewing a Vancouver study that found long-term care residents had a weaker immune response to their first dose of the Pfizer-BioNTech vaccine than younger healthy adults.

After supplies slowed to a trickle earlier this year, the National Advisory Committee on Immunization said provinces and territories can delay second doses by as long as four months.

That’s instead of the recommended schedule that spaces out the two-dose Pfizer-BioNTech and Moderna vaccines by three to four weeks, and the AstraZeneca product by four to 12 weeks.

Committee chair Dr. Caroline Quach said Thursday that NACI is looking at the Vancouver research, which found a weaker antibody response among older recipients but did not measure whether seniors were more likely to fall sick or die.

She said the findings will be assessed along with data from Quebec and the United Kingdom.

“What is so difficult with this disease is that there is no correlate of protection. That means that the presence and quantity of antibody present does not mean protection, or lack thereof,” Quach said in an email to The Canadian Press.

“Based on all those data, NACI will see if exceptions to the extended interval are necessary, keeping in mind that we are managing risk at a population level: the more people are vaccinated, the more likely we are to stop transmission, which will also be protective for the most vulnerable who may not mount an optimal response.”

The Vancouver data, funded by the COVID-19 Immunity Task Force, has yet to be peer-reviewed but adds to concerns about the rollout strategy of provinces including Ontario, Manitoba, Saskatchewan, Alberta, and British Columbia.

Task force director Dr. Tim Evans said the findings underscore a need to monitor senior recipients very carefully after their first shot.

“The immune response is so complicated and we still don’t fully understand what are called the correlates of protection,” Evans said from Montreal, where he is director and associate dean of the school of population and global health at McGill University.

“The most important takeaway from this study is we have to be very vigilant in monitoring the followup for the elderly, or immunocompromised with respect to extending the vaccine dose beyond what’s recommended.”

Evans stressed that older people in both long-term care and the community are well-protected for many weeks by a single dose of an mRNA vaccine, but said there may be limits to how long some people should wait for their second dose.

He said COVID-19 vaccines have already been associated with dropping hospitalizations and deaths in Canada, but expected NACI may have to refine its advice for how they be used in various populations.

“We’ve got multiple vaccines, they all work a little bit differently and so we know that we don’t have a one-size-fits-all approach,” he said, adding that long-term care residents may be more vulnerable than seniors in the community.

“We’re going to have to get used to working with different approaches for different age groups with different vaccines over the coming months as the vaccine rollout continues.”

The director of geriatrics at Toronto’s Sinai Health said a delayed-dose strategy makes little sense for a population already known to have a less-robust response to vaccines.

Dr. Samir Sinha said there’s already enough evidence for NACI to revise its advice, suggesting some urgency as he pointed to statistics that find 96 per cent of COVID-19 linked deaths are people over the age of 60.

“As a geriatrician, I’m becoming increasingly uncomfortable about the strategy of delaying these doses for older people and in particular, older people living in congregate care settings, and those who are highly vulnerable,” said Sinha.

Sinha acknowledged that NACI considers an array of factors in determining its guidelines and at the time of its March 3 decision, pressures included dwindling vaccine supplies, emerging variants and fears of a looming third wave.

Earlier Thursday, Health Canada’s chief medical adviser Dr. Supriya Sharma noted her agency – a separate body from NACI – approved the vaccines for use according to their respective labels.

She also said NACI’s advice will evolve as new science becomes available.

“I think it does make sense that we potentially have a more nuanced recommendation around that delayed second dose, but those conversations are ongoing,” Sharma said.

Principal investigator Dr. Marc Romney, an associate professor at the University of British Columbia, said not only did his study find LTC residents produced lower levels of antibodies, the antibodies they produced were less adept at blocking the SARS-CoV-2 virus from binding to its target cells.

“You don’t want to be leaving a large segment of society that’s already borne the brunt of the pandemic vulnerable to infection, awaiting a second dose – that is the potential issue here,” said Romney, medical leader for medical microbiology and virology at St. Paul’s Hospital, Providence Health Care.

“Hospitalizations are increasing again. And we have seen some outbreaks in long-term care facilities where people have been vaccinated, which is also concerning.”

He and a research team co-led by Dr. Zabrina Brumme of the BC Centre for Excellence in HIV/AIDS and Dr. Mark Brockman of Simon Fraser University analyzed blood samples collected from 18 long-term care residents and 12 healthcare workers.

They were taken in late 2020 and early 2021 before vaccination and compared to changes after participants received their first dose.

Just Posted

Regional District of Okanagan Similkameen offices in Penticton. (John Arendt - Summerland Review)
Regional District of Okanagan Similkameen showcases local government

The RDOS has put together a video as part of Local Government Awareness Week

The future of the Okanagan Lake watershed land use will be subject of a new study supported by a $300,000 grant from the Vancouver Foundation. (Contributed)
Grant to help develop Okanagan Lake protection strategy

Study receives $300,000 grant from the Vancouver Foundation.

Doctor Jessica Luksts is being recognized on BC Family Doctor Day for her part in the early days of the pandemic. (Submitted)
Celebrate BC Family Doctor Day on May 19

The South Okanagan Similkameen has over 80 family doctors serving the community

The wildfire season in the Okanagan Valley region has been approached with greater apprehension and concern from area residents since the historic Okanagan Mountain Park fire in 2003. That fire burned 25,600 hectares, forced evacuations in Kelowna and Naramata impacting more than 33,000 people, destroyed 238 homes, and claimed 12 wooden trestles and damaged two other steel trestles in Myra Canyon. (File photo)
Ominous wildfire outlook if June rains don’t return to Okanagan

Dry spring is fueling potential for busy wildfire season in July and August

Jim Moring, left, hands 132 letters and emails to Penticton Mayor John Vassilaki. The 132 people support Moring speaking on their behalf at the public hearing on May 17 for the development at the Kampe Estate. (Brennan Phillips - Western News)
Penticton neighbourhood rallying to speak as one against development of Kampe Estate

Resident Jim Moring delivered letters endorsing him to speak on the behalf of 132 people

Daily confirmed COVID-19 cases reported to B.C. public health, seven-day rolling average in white, to May 12, 2021. (B.C. Centre for Disease Control)
B.C. preparing ‘Restart 2.0’ from COVID-19 as June approaches

Daily infections fall below 500 Friday, down to 387 in hospital

A man and woman, both 33 and from Kelowna, were arrested on Postill Lake Forest Service Road in possession of two stolen vehicles Friday, May 14, 2021. (File photo)
Kelowna duo arrested with stolen vehicles after ‘brief’ bicycle getaway attempt

A man and a woman were arrested on a forest service road on numerous pending charges

The BC Conservation Officer Service (COS) handed out fines to two anglers on Shuswap Lake who were both casting more than one line, in violation of provincial regulations, Saturday, May 15, 2021. (COS photo)
Conservation officers snag Shuswap anglers for unlawful fishing

Two anglers were given $150 fines for casting two lines at once, against provincial regulations

On Friday, May 14 at Meadow Gardens Golf Club in Pitt Meadows, Michael Caan joined a very elite club of golfers who have shot under 60 (Instagram)
Crowds at English Bay were blasted with a large beam of light from an RCMP Air-1 helicopter on Friday, May 14. THE CANADIAN PRESS/Marc Grandmaison
Police enlist RCMP helicopter to disperse thousands crowded on Vancouver beach

On Friday night, police were witness to ‘several thousand people staying well into the evening’

Lynda Saundry, born 1961, is charged with the murder of North Okanagan resident Barry Jones in July 2020. Saundry will appear in Vernon court May 17, 2021, to fix a date for a preliminary inquiry. (Facebook public photo)
North Okanagan murder suspect to be tried by judge and jury

Lynda Saundry is charged with the first-degree murder of Barry Jones in July 2020

Vernon Search and Rescue’s Legacy vessel is returning to Okanagan Lake for boating season, the society said Friday, May 14, 2021. (VSAR photo)
Vernon Search and Rescue vessel returns to Okanagan Lake

VSAR’s Legacy is back with a fresh coat of paint and some other upgrades

People shop in Chinatown in Vancouver on Friday, February 5, 2021. THE CANADIAN PRESS/Jonathan Hayward
Vancouver community leaders call for action following 717% rise in anti-Asian hate crimes

‘The alarming rise of anti-Asian hate in Canada and south of the border shows Asians have not been fully accepted in North America,’ says Carol Lee

Sinikka Gay Elliott was reported missing on Salt Spring Island on Wednesday, May 12. (Courtesty Salt Spring RCMP)
Body of UBC professor found on Salt Spring Island, no foul play suspected

Sinikka Elliott taught sociology at the university

Most Read