When a COVID-19 vaccine arrives, which Canadians will get it first?

When the first COVID-19 vaccines become available, there won't be enough for everyone who wants it, both nationally and internationally.

We'll take a closer look at the issue with global vaccine distribution and prioritization in another article.

But for now, within Canada, who should get it first and how will that be decided?

Why we can expect vaccine shortages

There are more than 166 vaccines at various stages of preclinical and clinical (human) testing right now, the World Health Organization says.U.S. and European experts say under an optimistic scenario, the first of those vaccines could complete testing and get approval for distribution next year.

But then, a factory would have to produce them under the safety and quality standards required for something that's going to be injected into human bodies something it can only do at a limited rate, say experts such as Dr. Joel Lexchin. He's a professor emeritus at York University and an emergency physician in Toronto who has studied and written about pharmaceutical policy.

Meanwhile, with a global pandemic thathas wreaked havoc on countries' economies and people's lives around the world, there's a lot of demand for a vaccine from the global population of 7.8 billion people.

"Not everyone will be able to get it," Lexchin said. "And therefore we'll have to prioritize."

Because of that, it's expected, initially at least:

• Some countries will get more access than others.
• Some groups within those countries will get moreaccess than others.

We'll take a closer look at the international issues in another article, but here are some of the issues that leaders are dealing with in Canada.

How countries will decide the highest priority groups

When supplies are limited, countries will need to find a way to get the "maximum benefit for whatever minimal supply we have," says Dr. Noni MacDonald, a professor of pediatrics and infectious diseases at Dalhousie University and IWK Hospital in Halifaxwho has studied ethical issues related to vaccines. "That's what you have to do."

In Canada, that evaluation, based on evidence, is done by the National Advisory Committee on Immunization, which it says is guided by the goals of Canada's pandemic response:

• Minimize serious illness and overall deaths (including from causes other than COVID-19).
• Minimize societal disruption, including reducing the burden of health-care resources.

It says the vaccine is expected to play an important role in achieving that.

Of course, worldwide, front-line health-care workers who care for COVID-19 patients are expected to get the highest priority for access to vaccines, as they are at high risk of being exposed to the virus and are crucial for minimizing harms such as serious illness and deaths.

Beyond that, decisions get more complicated, but in general, countries are expected to target populations that are at very high or highest risk of severe disease and death, said Prof. Ruth Faden, founder of the Berman Institute of Bioethics at Johns Hopkins University in Baltimore.

"And those people will likely vary from country to country," she told CBC News. For example, in the U.S., she noted in an article in Futurity, obesity is having a major impact on the risk of severedisease.

Prioritization starts at clinical trialstage

For now, NACI is recommending which groups be targeted for clinical trials.

Faden saidthat's "critical," as vaccines might work differently in different groups and sometimes those groups may be left out: "There is a huge recognition and awareness of the importance of diversifying who will be involved in these Phase 3 trials."

For early phase (Phase 1 and 2) clinical trials, NACI recommends prioritizing not just healthy adults, who are typically used to test for safety, but also:

• Adults 60 years of age and older without underlying health conditions, because oftheir higher risk of getting severe disease.
• Children and adolescents, immunocompromised adults and pregnant women "as soon as it is feasible" to add them.

For late phase (Phase 3) clinical trials, when safety has already been established and the focus is on efficacy, NACI recommends prioritizing people:

• With health conditions that are risk factors for severe COVID-19, such as asthma, diabetes, hypertension, chronic lung disease and cardiovascular disease.
• Whose jobs make them more susceptible, such as other health-care workers, emergency workers, those who have a lot of social contact in their jobs or international business travellers.
• Whose social conditions make them more susceptible, such as those living in long-term care or crowded or remote locations, people who are homelessand those with tobacco, alcohol or drug use disorders. It may also include certain races or ethnicities or some immigrants or refugees and international travellers.

Who was prioritized for pandemic flu vaccination

The groups that are most vulnerable to COVID-19, including older adults, are a little bit different than they were for flu pandemics such as H1N1 (where pregnant women, infants and young children were most at risk). But the federally recommended priority groups when that vaccine rolled out give a sense of what prioritization forCOVID-19 vaccine might look like.When the first sevento 10 million doses of the H1N1 vaccine rolled out in 2009, here's who the government recommended vaccinating first:

• People with chronic medical conditions under the age of 65.
• Pregnant women.
• Children under five years of age (but not infants less than six months old.)
• People living in remote and isolated settings or communities.
• Health-care workers involved in pandemic response or who deliver essential health services.
• Household contacts and caregivers of individuals who are at high riskand who cannot be immunized (such as infants under six months of age or people with weakened immune systems).

The government noted that the list was not in order of priority, it was up to provinces and territories to adapt the guidelines to their needsand it could be adjusted as more was learned about the virus.

The U.S. CentersforDisease Control and Prevention havean even more detailed priority list for different levels of flu pandemic severity (COVID-19 is considered equivalent to the highest severity).

Why the groups for COVID-19 may be different

As mentioned, COVID-19 tends to be severe in different age groups than pandemic flu. But it also may spread more easily and has a wider range of symptoms including no symptoms and there's evidence that it can spread asymptomatically.

That's thought to be one of the factors behindsevere outbreaks among groups such as migrant farm workers and workers at meat-packing plants.

Lexchin suggests those are some of the groups he would prioritize for vaccination given the history of the pandemic in Canada so far, and it should be offered to everyone who works in a facility where they have close contact with multiple people.

"You have to assume that anybody in one of these vulnerable groups could be infected and therefore you have to [vaccinate] everybody."

In the U.S., there's evidence that Latino and Black residents have a higher risk of dying from COVID-19 than their white or Asian counterparts, and there's some evidence that race may be a factor in Canada, too. For example, Toronto recently reported that Black people and other people of colour made up 83 per cent of COVID-19 cases in the city, even though they represent only 50 per cent of the population.

Faden said, "There is an important conversation to be had about whether, as part of the much overdue racial reckoning in the U.S., we should consider putting people of colour high on the list for vaccine priority in the early days."

While it might sound controversial, she thinks it should be seen simply as prioritizing people who are at elevated risk "whether they're at elevated risk directly because of age or a relevant comorbidity or for any reason they are part of a group that's at elevated risk."

Which vaccine we end up with could affect prioritization

Beyond the differences in the course of the disease itself in different groups, the situation with COVID-19 is unique because of the huge number of vaccines under development, which are based on different strategies and technologies.

That means they will likely differ in terms of how big a dose and how many doses are needed, how quickly they can be produced in large quantitiesand how easy they are to transport and distribute. Some may also be more suitable for some populations than others for example, some may be better suited for older adults and others for younger people.

MacDonald gave the example of a vaccinethat works well in people aged 20 to 50 but hardly works in an 80-year-old. In that case, she said, "We're not going to get a very big effect by trying to immunize everyone in a long-term care facility but we would do very well to give the health-care providers who look after them the vaccine so they're less likely to bring infection in."

It's also possible that with some vaccines, certain people will require one dose and certain others, for example, older adults, will require two, MacDonald said. So twice as many people in the first group can be immunized with the same amount of vaccine.

"How is that going to weigh in? We've never had those kinds of considerations to make in the same way in the past with new vaccines."

MacDonald is among experts who hope that ultimately, multiple COVID-19 vaccines under development will make it to market and individuals will be able to access the one that's best for them.