Vaccination and previous exposure to COVID-19 best protection: UCalgary

New research from the University of Calgary (UCalgary) suggests prior infection and vaccination together as hybrid immunity is the best protection against COVID-19, yet it also warns people not to intentionally expose themselves to the virus.

The research, in collaboration with the World Health Organization (WHO), was led by Dr. Niklas Bobrovitz, who says hybrid immunity is backed by global data. However, it’s not meant to be confused with intentional infections.

“Having previously been infected does offer some protection against being re-infected again,” said Bobrovitz.

“Don’t go out there and get intentionally infected. It’s very dangerous to get COVID. And you could die, you could end up in the ICU. Or even if you have a mild infection, you could end up with long COVID and other challenges.”

Alberta Health Services (AHS) immunization website also highlights the benefits of hybrid immunity, but some experts, such as University of Alberta Sociology Professor Dr. Amy Kaler, worry this might send out the wrong message.

“By putting things on the provincial health website that suggests that getting an infection might be kind of like a booster and it might be good for you, this strikes me as really irresponsible,” said Dr. Kaler. “We don’t want people getting COVID. We want people to receive the vaccines that will enable them to reduce the risk of getting COVID, and also reduce their risk of getting really sick, if they do happen to get infected.”

Dr. Bobrovitz, says their research aimed at understanding the effectiveness of booster shots.

“So, the reason that we did this research was because many people have been infected, unfortunately, and many people have also been vaccinated,” said Bobrovitz. “So, we wanted to look at the more complex landscape of immune status to see how protected people are. And to sort of get a better idea of when booster shots might be most appropriate.”

In this study, investigators were able to look at immune protection against Omicron after a prior SARS-CoV-2 infection (the virus that causes COVID-19), vaccination, or hybrid immunity. WHO Scientist and senior author of the study, Dr. Lorenzo Subissi, says global emergence and rapid spread of the Omicron variant required scientists to conduct this timely study, and they found these results significant.

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“Protection against hospitalization and severe disease remained above 95 per cent for 12 months for individuals with hybrid immunity,” said Dr. Subissi. “We know more variants are going to emerge. The study shows to reduce infection waves, vaccinations could be timed for roll-out just prior to expected periods of higher infection spread, such as the winter season.”

Dr. Bobrovitz shares that the next step in this research is immune imprinting to predict better protection against COVID-19.

“There’s some evidence emerging, showing that whatever you were first exposed to — pre-Omicron or Omicron — it’s possible it might have implications for how strong your immune system is against COVID in the future,” Bobrovitz added.

The research published in “The Lancet Infectious Diseases” helps public policy makers understand the optimal timing of vaccinations. The study is supported by the WHO COVID-19 Solidarity Response Fund and the Coalition for Epidemic Preparedness Innovation (CEPI).