Is Omicron more dangerous? Will vaccines work? Here’s what we know so far

The Omicron variant was first identified in South Africa and has prompted a fresh wave of travel restrictions globally.

The World Health Organisation on Friday designated Omicron a “variant of concern”, with a statement from the organisation saying it “has a large number of mutations”.

COVID testing in Johannesburg. The new coronavirus variant detected in South Africa is causing concern due to its apparent speed of transmission.Credit: AP

“Preliminary evidence suggests an increased risk of reinfection with this variant, as compared to other variants of concern.”

While scientists say there is reason to be worried about Omicron due to those mutations, they warn there is still a lot that is not yet known about it, particularly about how effective vaccines will be.

Will existing vaccines be effective?

Paul Griffin, an Australian infectious diseases expert who has been the principal investigator for seven COVID-19 vaccine clinical trials, said his “greatest concern” was that the variant could cause reduced vaccine protection.

“The simple fact is it’s got some concerning mutations, but we are yet to establish whether that translates into any significant changes clinically,” he said. “We do need to just watch and wait a little bit.”

Professor Griffin, who is director of infectious diseases at Mater Health in Brisbane, said the most worrying element of the new variant was the 32 mutations found in its spike protein.

The spike protein is the chief target of antibodies that the immune system produces to fight a COVID-19 infection and is the part of the virus that vaccines target.

“If that changes significantly, the greatest concern is that our vaccine protection might be reduced,” he said.

Early findings are yet to provide a clear picture. However, there are concerns the new variant may be more transmissible and better able to evade the body’s immune responses, both to vaccination and to natural infection, than earlier versions of the virus.

What happens if vaccines are found to be less effective against Omicron?

Professor Griffin believes the current COVID-19 vaccines will most probably still offer some protection against Omicron, but further studies are needed to determine how much of the shots’ effectiveness may be reduced.

“We’ve seen some variants before that have had changes in the spike protein ... and the vaccine protection hasn’t been reduced as much as we first thought,” he said.

“The main thing is that if we do see a reduction we can actually tweak our vaccines fairly readily and quickly, so that we can get the protection we still need.”

Peter Doherty Institute director Sharon Lewin said current vaccinations were highly effective in protecting people against Delta, even though they were designed against the original Wuhan strain.

“I would say there’s a high chance that Omicron will be the same, but we don’t have the answers to that,” Professor Lewin said.

Within a week or two, South African scientists would have probably tested how antibodies behave against the new strain among vaccinated people.

“If that looks similar to Delta, then it would be very promising that the vaccine should perform well clinically,” she said.

Further tests should look at how people’s T cells protect against the virus and how the variant plays out in “real life”, which involves looking at the number of infections, hospitalisations and deaths among vaccinated and unvaccinated people.

Moderna, Pfizer-BioNTech and Johnson & Johnson have already confirmed they were testing an artificial version of Omicron against their vaccines. The companies said data should be available on this within two weeks.

Could a booster shot be developed to protect us against Omicron?

Kirby Institute virologist Stuart Turville, whose team has started building synthetic versions of Omicron, is concerned the new variant could take the edge off the vaccine response.

But he said a growing body of research had shown our immune systems can mature through booster shots. If Omicron does prove to evade current vaccines significantly, Professor Turville said booster shots could be developed that are specific to this variant.

Pfizer confirmed over the weekend its scientists “can adapt the current vaccine within six weeks and ship initial batches within 100 days in the event of an escape variant”.

The mRNA vaccines, in particular Moderna and Pfizer, have been built with technology that should permit rapid modification.

“They’ve been described as essentially ... sort of plug and play vaccines,” Professor Griffin said.

“We’ve still got the sequence for the original spike protein and it can just be swapped out for the sequence for the new variant’s spike protein and then we’ll get protection from that. It is something that can truly be done quite readily.”

Australia’s vaccine contracts allow for altered boosters from Pfizer and Moderna, but Australia’s Chief Medical Officer Paul Kelly said at the moment there was no evidence to suggest the vaccines were less effective against this variant.

Will Omicron overtake Delta and become the dominant variant?

Head of epidemiological modelling at Monash University’s School of Public Health James Trauer is worried about the early signs of the high transmissibility of Omicron.

It took Delta about two to three months to become the dominant COVID-19 strain, but it appeared Omicron was becoming dominant in half the time, he said.

“There’s been a few variants that have come up over the last year or something, and I haven’t always been quite as worried about them as I’m about this one,” Professor Trauer said.

“It looks like it’s got some sort of advantage over Delta.”

The variant also appeared to be spreading among people with high levels of natural immunity to the virus, suggesting current vaccines could be less effective in protecting people against Omicron.

Is Omicron more severe?

Professor Lewin said reports about symptoms from a single South African doctor were not enough to assess the severity of the variant.

New data likely to emerge from South Africa on the symptoms of the first 100 people in emergency and clinical practice in urban and rural settings would provide a clearer picture.

But Professor Lewin said it was very possible the variant could be less virulent because it was adapting to greater human immunity caused naturally or with a vaccine.

“Viruses want to survive and so therefore having greater success in transmissions is a good way to survive,” she said.

“Killing your patient very quickly is a really bad way to survive, which is why Ebola never spreads very far.”

Professor Kelly said on Monday that some earlier variants of the coronavirus had lost their “variation of concern” status after further investigation.

“Some reports out of South Africa are that it’s mostly mild,” he said. “Other information we have is that hospitalisation rates are increasing.”

He said it is possible that if Omicron turns out to be highly transmissible, but mild, that could give people who catch it immunity against more severe forms of the coronavirus.

“That would be my number one Christmas present,” Professor Kelly said. “Hope for the best and plan for other things.”

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