OPINION: The new NACI guidance on third doses is both excellent and lacking

What they’ve recommended regarding coverage of healthcare workers is, I think, more problematic. The summary document stated, “NACI recommends that a booster dose of an mRNA COVID-19 vaccine may be offered at least 6 months after completion of a primary COVID-19 vaccine series to: Adults who are frontline healthcare workers who have direct in-person contact with patients and who were vaccinated with an exceptionally short minimum interval.” 

All this because, “Evidence also shows that shorter intervals between doses in a primary series may result in lower immune responses and more rapid waning of protection.”

Canadian healthcare workers are seeing other countries prioritizing healthcare workers, from Israel to the United States to the U.K., largely because they were vaccinated early and work in high risk situations. This is certainly true for Canadian healthcare workers, many of whom are nine months out from their second COVID-19 vaccine. So, is there strong evidence that a longer interval between the first and second COVID-19 vaccine actually confers protection to them 6 to 10 months later against serious COVID-19 infections?

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Dr. Rick MacDonald, a community paediatrician in Ontario, clearly states the concern many healthcare workers have if they didn’t get their vaccines in “an exceptionally short minimum interval” and don’t qualify a third dose. “We’re expected to now immunize 5-to-11 year olds and children represent 30% to 52% of the new COVID-19 cases. We’re happy to do this, but we’re eight to nine months out from our second dose and would prefer to have our third dose for protection.” 

I looked further into the document from NACI and examined the research it, specifically the research supporting the statement, “A longer interval between the first and second doses also results in higher titres.” 

However, both articles referenced state, “This article is a preprint and has not been peer-reviewed. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.”

The first article has an N of 172, and measured titres for 3.5 months. The second article has an N of 750, and measured titres for 34 days after the second dose.

This hardly qualifies as proof that longer periods between doses increases protection for over six months, particularly since the issue that many are concerned with is protection against serious illness.

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A more robust study from Canada, studying a population of 13M in British Columbia and Quebec, with an analysis of samples from 2,460 hospitalizations and showed, “Vaccine protection was even better when the spacing between doses was longer than the three to four weeks recommended by manufacturers. Over the five- to seven-month period after the second dose, mRNA VE was maintained at about 95% against hospitalizations, showing some decline but remaining about 80% or more against infections.”

This is a small improvement from the study of over 4M with shorter intervals between doses showing, “Vaccine effectiveness against hospital admissions for infections with the delta variant for all ages was high overall (93% [95% CI 84–96]) up to six months.” 

However, no data in the Canadian study specifically looks at healthcare workers hospitalize. Given the fact they are exposed to high level of COVID-19, what protection do they have compared to the general population? And are they overrepresented in those hospitalized?

Further, there is no data I can find showing that prolonging intervals between first and second doses protects healthcare workers in high risk situations for up to nine months or more. 

If we step back from data, there is an important big picture to look at: during the pandemic we have had difficulty retaining nurses and doctors, in part due to burnout and exhaustion. Patients need more, not fewer healthcare workers. Asking healthcare workers to worry more, possibly get COVID-19 and be hospitalized is unfair to both them and the patients who need them, particularly when we have enough vaccines to provide third doses.

Read: How to get Canada off the healthcare teeter-totter

The other crucial issue about the NACI guidance is that certain vulnerable populations were left out, including intellectually delayed adults, who have been widely overlooked, “One year into the pandemic, the only published studies on the effect of COVID-19 on people with developmental disabilities are from other countries, such as the United Kingdom and the United States. There are no Canadian studies.”

Karyn Agyepong, registered nurse, has a 44-year-old sister who is developmentally delayed. “My sister Angie is a resident of a congregate care setting. . . . The population of developmentally delayed adults and children are at substantial risk. An American study states that, other than age, having an intellectual disability was the strongest risk factor for contracting COVID-19. This population has a third higher risk of mortality from COVID-19.” 

Her sister has an excellent family physician and Karyn finds this reassuring. However, as stated in my September article on third doses, doctors are unable to provide third doses outside of set guidelines. Given that some high risk patients will be overlooked, it would be wise to allow doctors the ability to protect their vulnerable patients. As Dr. Jennifer Kwan said, “There should be reasonable exceptions where physicians can make decisions for their vulnerable patients.”

There are two other important big picture issues about the NACI guidance. 

First, Hanukkah and Christmas gatherings are coming up, while most of those vaccinated are six or more months post second dose. If we fail to provide third doses in time to protect a wide swatch of the population, there could be a spike in infections, hospitalizations and deaths. With our present surplus of vaccines, this would be inhumane.

Read: How do you feel about COVID-19 booster shots in Canada?

Second, it is crucial to state that some people who are currently left out of the third dose NACI recommendations remain at risk from decreased immunity. Why? The answer is sadly illustrated in the story of Garry Weston.

Garry played hockey in three-on-three league for men over the age of 50. All players were fully vaccinated and in late September he got COVID-19. There were 15 COVID-19 cases linked to the hockey league. Garry’s only risk factor for a breakthrough infection was that he was 75 years old. He was hospitalized and died. 

Can vaccines prevent every infection? No. However, it is clear that the COVID vaccines have diminishing effectiveness as time passes from the second vaccine. This reduction in protection is faster with age. What we can do is tell people about it and not simply reassure them by opining on the ‘possible’ extended protection they ‘may’ have against serious illness. 

From my recent article on third doses, “In New Brunswick, as of Oct. 18, 2021, 20% of those who died from COVID-19 were fully vaccinated—most over 65 years of age. Their immunity has indeed decreased and Rodney Russell, a professor of immunology and infectious diseases at Memorial University of Newfoundland says that, "the reason we're seeing so many vaccinated, mostly older people getting infected now is because they think they're safe . . .. If you can't get a third shot, then you need to act like you haven't been vaccinated because you may not be protected.”

This must be said. If it isn’t, we risk lives that will otherwise be saved. 

So in short, make the third doses more widely available. Do it quickly before the holidays and inform people that their protection may be diminishing , particularly if they’re over 60 or immune compromised. And tell patients to behave with caution. 

Dr. Mary Fernando is a physician in Ottawa.