New Brunswick devises confusing way to measure vaccine protection

New Brunswick Public Health officials have come up with a new and confusing way of measuring the level of vaccine protection the population has against COVID-19.

Even Chief Medical Officer of Health Dr. Jennifer Russell struggled to explain it Monday in interviews with CBC News.

"We have 66 per cent of the population vaccinated now with their second doses and boosters," she told Shift New Brunswick.

On the same day, the province's COVID-19 dashboard showed 87.3 per cent of eligible people with two doses and 50.6 per cent with a booster dose.

Asked to explain her figure, Russell responded, "I can check that number. … I have the 66 per cent in front of me." 

She continued: "You've either had your second dose, or your second dose and booster. That's what we're considering fully protected right now." 

Health Department spokesperson Bruce Macfarlane explained in an email statement Tuesday that the figure represents the number of people who have had a third or booster dose, plus those who received a second dose in the last six months but did not get a third.

Research indicates that immunity from COVID-19 vaccines wanes after six months, so New Brunswickers who got a second dose before Sept. 15, 2021 and who did not get a booster would be less protected.

"Evidence currently suggests that protection against COVID-19 remains highest for six months following the second dose," Macfarlane said. 

Based on figures in government news releases, about 118,582 people have had second doses, but no booster, within the last six months.

Add that to the 380,762 people who have had boosters as of Tuesday's update, and you get 499,344 people — or 66.6 per cent of the eligible population as of Monday.

Numbers hard to track

University of Ottawa epidemiologist Raywat Deonandan says it's a "useless" measure that muddies the message on how many doses people should have.

"If fully vaxxed is three doses then that's what matters," he said in an email. "If fully vaxxed is two doses, then that's what matters."

Several studies have shown that while two doses offer some protection against severe illness, hospitalization and death from the now-dominant Omicron variant, three doses are better.

Back in January Russell said it was "urgent" that every eligible New Brunswick get a booster shot.

"Booster shots increase protection against getting hospitalized to nearly 90 per cent," she said.

The new number is also harder for the public to track.

New Brunswick's COVID-19 dashboard continues to display the number of people with one, two and three doses, but doesn't say how many of those with two doses had their second shot in the last six months.

Macfarlane said the province's vaccine web page "will continue to be updated weekly to show how many individuals have received doses of the vaccine," but he did not respond to whether the new hybrid number would be added.

He said graphics showing people in hospitals, intensive care units, on ventilators or dying with COVID-19 "are split by protection status" though it doesn't distinguish between second shots and boosters.

If the province doesn't add the figure itself, users will have to look up vaccination figures from six months earlier, calculate how many people got second doses since then and do the math themselves.