What we know about Omicron two weeks after it became a variant of concern

This is a 10 December 2021 article by Nicole Bogart, CTVNews.ca, @nlynnbogart. The original article can be found here.

Two weeks after the World Health Organization designated Omicron a variant of concern, it has dominated headlines, sparking renewed fears about the spread of COVID-19 and forcing countries to strengthen their vaccination campaigns with booster shots.

Over the last several weeks, health officials across the globe have been paying close attention to Omicron cases to answer important questions like how transmissible it is, how good it is at evading immunity from vaccines or past illness, and whether it causes more severe illness.

Their work has painted a more complete picture of how the variant spreads and how concerned we need to be.

No signs of increased severity

On Friday, scientists in South Africa, where the variant was first detected, said they have seen no sign that Omicron is causing more severe illness, despite increased rates of hospitalizations.

Hospital data shows that COVID-19 admissions are rising sharply in more than half of the country's nine provinces, but deaths are not rising as dramatically and indicators such as the median length of hospital stay are reassuring.

"Preliminary data does suggest that while there is increasing rate of hospitalization ... it looks like it is purely because of the numbers rather than as a result of any severity of the variant itself, this Omicron," the country’s health minister, Joe Phaahla, said Friday.

ICU occupancy in South African patients with confirmed Omicron cases sits at just 6.3 per cent, much lower than previous Delta wave, with fewer patients requiring supplemental oxygen to help them breathe.

To date, all reported cases of Omicron in Canada have been asymptomatic or mild.

Experts say it is possible that Omicron has mutated to become less severe – but it’s too early to make that assumption, especially without concrete data to show how many people that are sick with Omicron are vaccinated or have had previous COVID-19 infections.

“Here's the thing for everybody to keep in mind. Most of the cases that we're hearing about happening are in people that have had COVID before who have had vaccines,” Sarah Otto, virologist at the University of British Columbia, told CTV National News.

“What is really unknown at the moment is how severe cases will be among people that have never had any exposure whatsoever. And I think here in Canada, we have still have a large proportion of the population that is not vaccinated, not just children, but then another 10 to 15 per cent of adults that are also not vaccinated and at risk of severe cases.”

Omicron is spreading fast

New cases are rising steadily in South Africa, the epicentre of this variant’s outbreak.

In the past few days, a nationwide outbreak linked to Omicron has been infecting around 20,000 people a day, with 19,018 new COVID-19 cases on Thursday, according to data from the country’s National Institute of Communicable Disease.

However, infections have yet to reach the peak of more than 26,000 daily cases during a third wave fuelled by the Delta variant.

In the U.K. – where officials expect Omicron to become the dominant strain in the next two to four weeks – preliminary studies of household contacts found a higher risk of transmission from Omicron when compared to Delta.

While the Delta variant remains the dominant strain in Canada and around the world, the spread of Omicron is increasing globally. And in Canada, there are early signs of community spread.

While most of the confirmed Omicron cases in Canada have been traced back to international travel and close contacts, cases with no known links to travel are starting to be reported, Chief Public Health Officer Dr. Theresa Tam noted during a press conference on Friday.

Some Canadian provinces are already seeing a jump in daily case counts, which could be aggravated further by the spread of Omicron, Tam said.

The current rise in new cases is primarily driven by Ontario and Quebec, with both provinces experiencing numbers not seen since spring. Should transmission rates increase by 15 per cent, or if Omicron takes hold under current levels of transmission, then Canada could see cases skyrocket to record levels above 10,000 cases before January, modelling charts show.

“We must approach the coming weeks with an abundance of caution and at the same time, we must be prepared to act quickly to control the spread at the first sign of rapidly accelerating cases,” said Deputy Chief Public Health Officer Dr. Howard Njoo.

Genetic mutations linked to the common cold

A stand out factor about the Omicron variant is the sheer number of mutations to the virus’s spike protein, which allows it to bind to human cells and gain entry to the body.

But a new study suggests that Omicron likely acquired at least one of its mutations by picking up a snippet of genetic material from another virus – possibly one that causes the common cold.

This specific genetic sequence does not appear in any earlier versions of SARS-CoV-2, the virus that causes COVID-19, but is common in many other viruses including those that cause the common cold, and also in the human genome, according to researchers.

Lead study author Venky Soundararajan of Cambridge, Mass.-based data analytics firm nference, suggests this may mean Omicron is attempting to make itself look “more human” to trick the immune system.

What about vaccine immunity?

In an update this week, WHO said existing vaccines should still protect people who contract the Omicron variant from severe illness, but noted that preliminary lab tests from South Africa suggest the variant can partially evade the Pfizer jab.

On Wednesday, Pfizer released preliminary data suggesting that two doses may not be protective enough to prevent an Omicron infection, but a booster increased by 25-fold people's levels of virus-fighting antibodies against the Omicron variant.

However, those findings are preliminary and haven't yet undergone scientific review.

Several countries have already announced booster shot initiatives in light of the Omicron variant.

Ontario announced Friday that anyone over the age of 18 will be eligible to book a booster shot in January. Several other provinces, including Alberta and B.C., have expanded their booster shot program. However, Canadian officials have said the efficiency of booster shots remains to be seen.

“The extent of the protection against Omicron from the primary series and booster dose remains to be seen, and we're going to learn a lot about this in the days to come,” Tam said during a news conference last week.

“But nevertheless, it is still prudent to maximize the possibility of protection from vaccine by, first of all, offering the vaccine to anyone who hasn't had the primary series, but then offering the boosters.”

The National Advisory Committee on Immunization strongly recommends that adults aged 50 and older receive a COVID-19 booster shot. The committee also made a discretionary recommendation on booster shots for Canadians 18 to 49 years of age, saying they “may” be offered a third dose based on individual risks and where they live – recommendations that would have been made with or without the presence of the Omicron variant.

While there is a good chance current vaccines may not be as effective against the Omicron variant, experts say they are still likely to offer some level of protection given their role in helping the body develop antibodies and T-cells to fight off the virus.

“It's very unlikely that it's going to completely make our current vaccines obsolete,” Dr. Susy Hota, medical director for infection prevention and control at the Toronto-based University Health Network, previously told CTVNews.ca.

“They may be reduced in effectiveness, but there's still a very broad immune response that these vaccines elicit. “If we can increase the overall protection, it just puts us in a better place with all the variants that we're dealing with.”

- With files from Jennifer Ferreira, The Canadian Press, The Associated Press and Reuters