BOOSTERS MAY BE THE FUTURE

Immunity wanes in the vulnerable

Earlier this month, a fully vaccinated health worker at an Ottawa long-term care home where 18 residents died last year, tested positive for the Delta variant of COVID -19.

Testing of residents and staff indicated the infection hadn't spread beyond the worker, but that kind of scenario is one reason the Ontario government is now offering third doses to vulnerable long-term care residents who bore the brunt of the pandemic during earlier waves.

Vaccinated long-term care residents have lower immunity to COVID than younger people. That immunity wanes relatively quickly, and they are more at risk for exposure and serious outcomes if they get infected. Given the prominence of the Delta strain and cases like the one recently at an Ottawa care home, long-term care residents are at risk without a booster, experts say.

Some say the move could foretell booster vaccines for the broader population in the future, despite global pleas for wealthy countries to wait until the rest of the world is vaccinated before widely distributing third doses.

The World Health Organization has called for a moratorium on boosters and condemned wealthy countries for offering third doses while much of the world is waiting for vaccines.

“We're planning to hand out extra life-jackets to people who already have life-jackets, while we're leaving other people to drown without a single life-jacket,” said Dr. Mike Ryan, director of the WHO's health emergency program this week.

On Wednesday, the U.S. government said it planned to make booster shots widely available beginning in September. Other countries, including Germany, are offering them to more vulnerable residents.

In coming months, Canadian officials will grapple with the difficult ethical questions of whether to allow more people to get a third dose amid a dangerous variant when much of the world remains unvaccinated.

“It is a tough question,” said Dr. Kumanan Wilson, a senior researcher at The Ottawa Hospital Research Institute and CEO of CANImmunize Inc., an Ottawa company specializing in immunization software.

“From a global equity point of view, we need to make sure vaccines are distributed everywhere. But we live in a democracy where we have to respond to the electorate. For a political party to say it is not going to give boosters would be difficult,” he said — especially if cases and hospitalizations rise during the fourth wave.

“I do think we are going to end up there.”

Part of the reason, he said, is the nature of the Delta variant. That played a key role in this week's announcement of third doses for long-term care residents and others in Ontario.

On Tuesday, amid a flurry of announcements aimed at tamping down the fourth wave of the pandemic in Ontario, Chief Medical Officer of Health Dr. Kieran Moore revealed the province would begin offering third doses of vaccine to those at highest risk, including transplant patients, the immunocompromised and long-term care residents.

“Evidence shows that beginning four months after receiving two COVID-19 vaccine doses, the immune response in residents who live in long-term care homes wanes significantly compared to the general population,” the Ministry of Health said in a statement.

Health experts say offering a third dose to long-term care residents makes sense, especially given the dominance of Delta and residents' risk of severe illness and death.

Offering third doses to longterm care residents is “a medical requirement,” said Earl Brown, a virologist and emeritus professor at uOttawa. “They are more likely to have a problem and die” if they become infected with COVID -19. “That is a medical need.”

Long-term care residents made up the vast majority of deaths from COVID-19 during the first and second waves of the pandemic in

Ontario. Deaths in long-term care across Canada have been among the highest in the world during the pandemic.

Because of their vulnerability, long-term care residents were also among the first to get fully vaccinated in Ontario and across the country. And, unlike most other residents, they received their second doses according to the manufacturers' guidelines — either three or four weeks after the first dose.

That means it has been six months since many LTC residents were fully vaccinated, and their protection, according to the Ontario government, has now waned “significantly.” Research has also shown that extending the period between doses, as was done for the general population, conferred better immunity, something long-term care residents didn't benefit from.

Immune response, in general, is not as high in the elderly. But vaccines have still done a good job of protecting LTC residents and others against serious illness, and outbreaks and serious infections in long-term care homes have dropped dramatically in recent months.

Recent research from the U.S. Centers for Disease Control and Prevention suggests mRNA vaccines continue to protect people against hospitalization at a rate of about 85 per cent for 24 weeks.

Wilson said research is ongoing in Ontario to better understand how well people are protected against severe illness and death over time.

He said immunity is not so much fixed as it is a gradient that can change depending on several factors, including the age and health issues of people, the characteristics of the variant and time.