Full vaccine series plus prior infection best COVID defence: UCalgary, WHO research

Those with hybrid immunity had above 95 per cent protection against hospitalization and severe disease for 12 months, the study found

FILE PHOTO: A nurse gives out COVID shots as part of the City of Calgary’s extension of its mobile vaccination outreach program, a short-term COVID-19 vaccination station launched at Southcentre Mall on Monday, January 3, 2022. Darren Makowichuk/Postmedia

The best protection against COVID-19 illness comes from the combination of a full vaccine series and a prior infection with the virus.

That’s according to new research from a University of Calgary team alongside the World Health Organization which aimed to determine the best defence against the novel coronavirus.

The analysis of global data found hybrid immunity — previous infection with COVID-19 plus vaccine protection against the virus — results in the greatest reduction of severe illness and reinfection.

The study, published in The Lancet Wednesday, underscores the value of immunization against COVID-19, said researcher Dr. Niklas Bobrovitz.

“We previously had a pretty good idea of how much protection COVID-19 vaccine provided, but a lot of people have been infected as well, and it was unclear how much protection this hybrid immunity provided,” said Bobrovitz, a researcher with SeroTracker, a U of C-based team analyzing worldwide prevalence of COVID-19 infections.

“(It also told us) how long people have protection for, and finding that out is important to plan booster shots.”

Hybrid immunity effective, but risks come with contracting COVID

Those with hybrid immunity had above 95 per cent protection against hospitalization and severe disease for 12 months, the study found, with a need for subsequent shots to boost protection after that time period.

Those findings suggest public health officials could time booster vaccination campaigns ahead of periods of expected greater spread to maximize effectiveness, Bobrovitz said.

The researcher added that though prior COVID-19 illness does provide some defence against future infection, it’s unwise to intentionally contract the disease.

“People should not purposely get infected. There’s huge risks associated with that. You can die, as millions of people have. You could end up in the ICU. Even if you have a mild infection, you could end up with long-term consequences like long COVID,” Bobrovitz said.

Lower vaccine uptake among younger Albertans

Through Jan. 16, Alberta had administered just shy of 10 million doses of COVID-19 vaccine.

Among Albertans age 12 and older, 91 per cent have had at least one shot, and 87.6 per cent have had two or more doses.

Those numbers fall off among those age six months to 12 years, with 34.5 per cent having one shot and 28.7 per cent having two or more.

Vaccines are available in Alberta for everyone six months of age or older.

Bivalent booster shots, which are designed to protect against the dominant COVID-19 Omicron variant as well as the original virus strain, are also available for those age five and older. Bobrovitz said the next step of his team’s research is to investigate how effective bivalent boosters are for people who have previously had COVID-19 infection.

“We’ll be looking at the Omicron-specific vaccine to see how it stacks up,” he said.

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Twitter: @jasonfherring