It’s been a while since a whole new COVID-19 variant burst onto the scene, but like a pop star with staying power, good old Omicron keeps finding new ways to reinvent itself.
A new iteration of BA.2 — BA.2.12.1 — is rapidly growing in the northeastern U.S., and is already spreading in Canada. Meanwhile, scientists are keeping an eye on two other members of the crew, BA.4 and BA.5, that are causing some concern in South Africa and have been detected in several other countries.
The ability that this group of subvariants has to continuously evolve — getting more contagious with each new mutation and finding ways to get around vaccination — has left vaccine researchers scrambling to keep up and a weary public wondering if this game of viral whack-a-mole will ever end.
“The problem is that the virus still is evolving quicker than we can update the vaccine,” said Matthew Miller, Canada Research Chair in Viral Pandemics and an associate professor at McMaster University.
Infections are also still quite high globally, and “each one of those is just a lottery ticket for the virus to be able to learn to do something it couldn’t do before,” he added.
Omicron contains mutations on the spike protein of the SARSCOV-2 virus, which help it to infect even people who’ve been vaccinated or had a previous version of COVID.
What we’re seeing now are “better and better versions of Omicron as opposed to another virus that’s coming out of left field,” said Miller. “The easiest path for the virus is for Omicron just to continue to improve upon itself.”
BA.2, a more contagious subvariant of the original very contagious Omicron, is now dominant globally and is circulating widely in Canada. In Ontario, BA.2 lineages now make up just over 90 per cent of cases that have been sequenced, according to Public Health Ontario.
Sarah Otto, a professor at the University of British Columbia, said that its descendant BA.2.12.1 is also present across the country and now making up almost half of the new cases. That’s according to a project called the Global Initiative on Sharing Avian Influenza Data (GISAID), which provides open data on the genomic profile of viruses from samples shared by public health authorities.
“It’s not spreading so fast that it’s super-alarming, but it is spreading relative to BA.2,” said Otto, who’s part of the national Coronavirus Variants Rapid Response Network (CoVaRR-Net), a group of Canadian scientists tracking variants. This could make the BA.2 wave that’s already here “a little longer, a little higher, because of BA.2.12.1 contributing and appearing to spread more.”
South of the border, BA.2.12.1 was responsible for just over 36 per cent of new nationwide infections last week, and in some northeastern states the subvariant has become dominant, according to the Centers for Disease Control and Prevention . In New Jersey and New York, about 62 per cent of new infections as of April 30 were from BA.2.12.1. CDC director Rochelle Walensky has said preliminary research suggests BA.2.12.1 is 25 per cent more transmissible than BA.2.
“It does seem to replicate better and it probably does escape some pre-existing immunity a little better than the parent BA.2,” said Robert F. Garry, a professor of microbiology and immunology at Tulane University in New Orleans.
Garry explained that as viruses replicate, changes to their genetic codes are introduced. Most of the time, he said, these mutations weaken the virus, meaning it’s harder for the virus to compete.
“But occasionally you’ll get one that has picked up a mutation … that gives it a bit of an edge up on the other variants,” he said. “That one will outcompete the rest and that’s what we’re seeing with the new Omicron variant.”
The good news is that BA.2.12.1 does not appear to cause more severe illness than BA.2, which itself causes less severe illness than the previous variant Delta.
In a pre-print study recently posted online but not yet peer-reviewed, scientists in South Africa said that two sub-variants there, BA.4 and BA.5, seem to be able to get around antibodies produced by individuals who had the original Omicron, suggesting the potential for a new wave.
As of press time there were three cases of BA.4 in Canada, two in Ontario and one in Quebec, reported to GISAID, and one case of BA.5 in Toronto linked to international travel.
But Otto said South Africa didn’t really have a BA.2 wave, and Canada, in the middle of one, could be left with more protection against BA.4 and BA.5.
“Eventually we’ll see waning of the immunity built by these Omicron infections and we’re going to see something else come in, but the timing might not be right for BA.4 and BA.5,” she said.
McMaster’s Miller said many experts feel “considerable unease and a certain amount of trepidation about where the pandemic’s heading” because cases are still not under control.
As well, the public hasn’t really gotten a break from what can seem like one long blur of infections rather than the bit of breathing room between the original version, Alpha and Delta.
“The level of infectiousness and the ability of Omicron to really infect and transmit in people who had already been vaccinated plays into what we’ve seen with this sort of really extended Omicron wave that’s also contained ripples on top of it, as these new Omicron subvariants have popped up,” he said.
Miller and his team are working on a new kind of booster vaccine that would be inhaled, instead of injected in the arm.
The idea of the new vaccine, which doesn’t target the spike protein, is that it would give broader immunity to future variants, and also stop the infection in its tracks before it gets into the rest of the body.
A team at Yale is also working on something similar that would be taken up the nose.
“There’s no way that we can keep up with this rate of viral evolution,” Miller said. “So targeting parts of the virus that are far less prone to change is going to be very important going forward.”
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The problem is that the virus still is evolving quicker than we can update the vaccine.
MATTHEW MILLER CANADA RESEARCH CHAIR IN VIRAL PANDEMICS