“We will not end the pandemic”: because those hopeful results of vaccine trials are not all they seem

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“There is still a lot to be said against the background of the exciting press releases,” said Dr. Gerald Evans, head of the infectious disease division at Queen’s University School of Medicine.

Completely preventing infection is a very high goal to achieve

It’s possible the vaccine actually prevented the infection, and not just the resulting disease, but the results so far don’t prove this, experts say.

“If (the infections) were not confirmed in the laboratory with routine testing in all participants, then we would not know the impact on asymptomatic disease,” said Julie Bettinger, a University of British Columbia professor and vaccine safety scientist.

However, it may not be as troubling as it sounds, although asymptomatic people can spread the virus.

Actually preventing infection – as opposed to just warding off symptoms or serious illness or death – is something that relatively few vaccines can accomplish, said Dalhousie University immunologist Dr.

A vaccine that could simply “downgrade” COVID-19 from a virus that is sometimes deadly to a common cold would be very welcome, he said.

“Preventing infection completely is a very high level to achieve,” Halperin said.

Evans agreed, saying that a vaccine that provided “sterilizing immunity” – staving off the infection itself – would be a surprising development. But even one that only offered “protective immunity” – preventing people, especially the most vulnerable, from getting sick when they contract the virus – would be a “huge step forward,” he said.

Meanwhile, experts are debating how approval of Pfizer and Moderna vaccines – the first to cross the line in a massive global effort – will affect those yet to come.