Why getting a booster shot is growing more crucial as omicron spreads

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Omicron is ramping up the push for widespread boosters in Canada, shifting the conversation away from providing added protection to the most vulnerable and toward giving everyone eligible an additional shot to stave off potential spread of the highly transmissible variant. 

Canada has seen dozens of omicron cases emerge in the two weeks since the variant was first identified, and new data from around the world has public health officials on high alert for signs of wider spread here. 

But while there is growing concern about the threat of omicron as we learn more about it in real time, there are also early, hopeful signs that it may not cause as severe illness as previous variants and that boosters may be effective at slowing its spread.

A new report from the U.S. Centers for Disease Control and Prevention found that out of the 43 omicron cases identified in 22 states in early December, just ​​one person needed a brief hospital stay, and there were no reported deaths from the variant.

WATCH | Omicron spreading faster than delta but may be milder, early data suggests:

"We are seeing fewer symptoms so far with omicron, and it almost certainly has a lot to do with the fact that people have some degree of immunity," said Deepta Bhattacharya, an immunologist at the University of Arizona.  

"But I don't think there's any doubt that omicron has more immune-evasive properties than delta … so you can imagine that omicron would have more of an advantage spreading in places where people already have some immunity than with delta."

South Africa reported a near-record high in daily infections this week, but scientists have not yet seen evidence that omicron is causing more serious illness, which could either be a sign of things to come or a delay in the true impact it will have there. 

"The severity does not look very high, which is good, but the infected population is skewing young and so would be expected to have milder infections," said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health in Boston.

"The real concern is unvaccinated populations."

A new report from the U.K. confirmed widespread community transmission of omicron and a higher rate of re-infections and household outbreaks compared to delta — with more than one million omicron cases projected in the next month.

Yet the report also found booster shots provided an estimated 70 to 75 per cent protection against mild disease from omicron, giving the first real-world glimpse at the benefit offered by third doses in the face of the fast-spreading variant. 

"While the data isn't perfect, and of course there's still a lot of questions that remain, all the arrows are pointing in the direction that two doses of a vaccine will still be very helpful — but three doses of a vaccine will be better," said Dr. Isaac Bogoch, an infectious diseases physician and member of Ontario's COVID-19 vaccine task force.