In the race to stamp out COVID variant, can Montreal's pilot project succeed? Experts weigh in
MONTREAL -- The controversy surrounding a COVID-19 variant-targeted vaccination pilot-project in dozens of schools and daycares in two Montreal neighbourhoods has not died down, and an immunologist is critical of the way Montreal Public health has rolled it out.
“I don’t disagree with their approach, but I do think public health needs to work a little bit more on their effective communication,” said Dr. Donald Vinh.
He suggested health officials should have better explained the science behind their strategy and what kind of success it could have when they first announced it.
In that light, the anger from parents, teachers and others around the design of the project is understandable, said Vinh.
“People want to know if this is a scientifically valid approach.”
There have also been questions about why certain schools within the same postal code boundary are excluded, and confusion expressed about the vaccine’s ability to reduce transmission.
Added to that is frustration about the health departments contention they’re short of doses when appointments are still open.
“I find it a difficult answer to swallow that there aren’t enough doses,” said Dr. Debbie Schwarcz, a parent at Merton Elementary who wants her school on the list.
A teachers union, the Federation autonome de l’enseignement, asked the province last Wednesday to implement targeted vaccination of teachers, staff and parents in all schools, as soon as there is a presumed variant case detected.
IT’S KNOWN AS RING VACCINATION
Despite all the questions and justifiable concerns, the scientific premise behind the pilot project is sound, said Vinh, who is an infectious diseases expert at the MUHC’s research institute.
It’s called ‘ring vaccination’ or ‘ring immunity’, and it can be a very effective way to stamp out a disease, said Vinh, with the caveat, “if it can be done properly.”
“It’s based on the idea of when you throw a pebble into the water you’ll naturally get a ripple from that and what you want to do is prevent transmission, put barriers up so the ripples don’t spread,” he said.
The public health strategy is regularly used worldwide, and was carried out in the Democratic Republic of the Congo just a few years ago to control the Ebola outbreak.
Closer to home, there was an outbreak of meningococcal disease in Quebec about two decades ago.
“It was pretty devastating. People were losing limbs because of the severity of the illness and it was affecting young adults who were college age, and so public health went in and vaccinated all around it,” Vinh said.
CAN THE PILOT PROJECT SUCCEED?
Vinh said the variants do pose a threat and it’s better for the health department to act, rather than do nothing, but success is not assured and will be hampered by several factors: competing priority groups and a limited vaccine supply.
“I think that’s a major problem here. If there was not a vaccine supply issue I think we would just vaccinate everybody,” because to stamp out the spread of variant cases, “you ideally should be vaccinating every close contact, every potential transmission in the chain,” Vinh explained.
But Montreal Public Health has announced teachers and daycare staff will be vaccinated, but not support staff, and no word on whether there are additional adult household contacts that may also be worthy candidates.
And, at least one school in Cote-St-Luc and the specific parts of Cotes-des-Neiges targeted is not included at all.
The health department said it has been allotted a supply of only 15,000 vaccines to get the job done.
That’s why a systematic approach appears to be unlikely. There will be gaps in the vaccination ring and variant cases will likely leak through, said Vinh, resulting in some community spread anyway.
“You have to be careful because in the process if you use up your vaccines, if there are flaws, then you’re compromising your original priority to vaccinate high risk groups.”
But he said in situations like this one, where vaccination coverage may be less than optimal and not capable of aborting variant transmission altogether, transmission might at least be slowed down.
“And that’s still a win-win. I still think either one of those outcomes is a win,” said Vinh, given the current vaccine supply.
WOULD LOCALIZED LOCKDOWNS WORK BETTER?
Testing out 'ring vaccination' is one way to try and deal with highly-contagious variants, but one medical expert said the serious circumstances call for more restrictive measures to be put in place as well.
While Dr. Jorg Fritz, an associate professor in the department of microbiology and immunology at McGill University does see the pilot project as "one of the last strategies to put out the fire," he called the effort “a longshot” if employed on its own.
He suggests the best way to squelch the variants is to set up a perimeter around the areas where there are variant clusters and keep them locked down while vaccination proceeds.
In some countries where localized lockdowns are enforced, people can’t exit or enter for a time, without a negative test result.
“I’m Austrian and in west Austria at the end of January, there was a big outbreak in one area and they really cut it off and vaccinated 40,000 people in that area. That really got it under control. So I think a combination might have been better to contain it.”
Fritz also said until there are vaccines approved for children, he thinks there will always be flare-ups.
That’s just one of the built-in limitations of the project, he said, along with the likelihood that some people in any targeted group may be hesitant to get the vaccine, weakening the outcome.
CAN VACCINES PREVENT TRANSMISSION?
As with most vaccines, the COVID-19 shots were developed to prevent disease, primarily serious ones. But the secondary gain is that they usually prevent transmission of the particular illness as well.
Dr. Vinh said in the last few months, data has become available that suggests the COVID vaccines also have an impact on transmission.
“With the Pfizer vaccine, we know that 3-4 weeks after the first dose...people who get the vaccine are 50 to 70 per cent less likely to be able to transmit the virus.”
The related studies demonstrated that the vaccinated individuals have a lower risk of having detectable virus in their noses, despite exposure to COVID-19, he explained.
Vinh said the level of protection will vary depending on the type of vaccine administered and the variant that is circulating, but the vaccines approved so far do appear to reduce spread.
“Even a 25 to 30 per cent reduction is really important in a ring vaccination strategy,” said Vinh.