Vaccinate the young first to halt spread of COVID-19, experts say

As Ottawa nears a major milestone in the vaccination campaign against COVID-19 — half of the city's adult population will soon have had a first dose — some experts are asking whether we've taken the right approach.

Some believe that to keep hospitalizations in check and prevent the spread of the illness among older residents, we should have started by vaccinating the young.

We can prevent more hospitalizations ... and more deaths by vaccinating people who have a high number of contacts.- Caroline Colijn, Simon Fraser University

"Younger groups are where we see the most transmission. If we can get high levels of vaccination in those, it will make a big impact for the entire community. It will save lives for older people as well," said Doug Manuel, a senior scientist with The Ottawa Hospital.

The idea isn't new. A 2001 Japanese study found that vaccinating school-age children against influenza prevented tens of thousands of deaths among elderly and at-risk populations over a 25-year period.

A different approach

In the context of COVID-19, Manuel said a successful vaccination campaign would still begin with the most vulnerable, such as residents over 80 and anyone in long-term care, but would then turn its attention to the 20-40 set instead of tackling the different age groups in descending order.

"I think we would be in a better position in this so-called third wave ... if we had been proactive ... when we had really scarce vaccines, if we had tried to use them as effectively as possible," said Caroline Colijn, Canada 150 Research Chair in mathematics for infection, evolution and public health at Simon Fraser University.

"We can prevent more hospitalizations per vaccination and more deaths by vaccinating people who have a high number of contacts .... people who are at risk of being exposed in the first place and at risk of infecting others." 

Many of those people Colijn is talking about are essential workers — teachers, first responders, social workers, farm labourers and those who work in transportation, retail and the warehouse sector —  and many fall into the 20-40 age group.

Vaccinate them, and you greatly reduce the risk to others, Colijn said.

"The benefit to [younger people] is good, but there's also an indirect benefit. If they're working in jobs where they're likely to be exposed, then that exposure poses a risk not just to them, but to everyone around them."

Targeting hot spots

So why haven't public health units been targeting younger essential workers before older age groups? Manuel and Colijn said in a way, some have.

As part of the first phase of its vaccination campaign, Ottawa Public Health (OPH) began targeting high-priority neighbourhoods with high rates of COVID-19. 

Manuel said this approach also captures many residents who work in essential services, live in multi-generational homes or may otherwise be considered high-risk.

Despite a significant amount of debate in Canada, Manuel said the general consensus nevertheless favoured simplicity, opting for a "pretty effective" top-down rollout instead of a more complex model.

Vaccine 'miracle'

It's now well-known that COVID-19 vaccines don't just protect those who are vaccinated.

A U.K. study found the Pfizer-BioNTech vaccine was effective at preventing both symptomatic and asymptomatic infections, including those caused by the B117 variant, which now dominates new infections in Ottawa.

"If you protect someone who's working in a high-contact workplace, they don't get infected, they don't cause an outbreak. Those people who [the worker] may have infected also don't get infected, and you may … prevent 10 infections," Colijn said.

"You've actually had more benefit on hospitalizations because each of those 10 people could have been an elderly person."

"We've learned a lot with vaccination programs over the years, and the incredible power of this ability to control disease by controlling transmission," said Manuel. "Vaccinations are sort of a miracle public health intervention."