29 Nov 2021

Omicron: how worried should we be?

From Nine To Noon, 9:05 am on 29 November 2021

Omicron has a large number of mutations, and early evidence suggests an increased reinfection risk, the World Health Organisation says.

Travel restrictions are being reintroduced around the world after a new Covid-19 "variant of concern" was detected. 

It's the first strain to be declared a variant of concern since the detection of Delta.

People wearing masks cross an almost empty shopping street in Melbourne on May 26, 2021, as Australia's second biggest city scrambles to contain a growing Covid-19 outbreak. (Photo by William WEST / AFP)

Photo: AFP

Kathryn Ryan asks evolutionary virologist at the University of Otago Dr Jemma Geoghegan how concerned we should be about the outbreak of this new variant.

Geoghegan says they do know that Omicron has a number of mutations that would help it spread more quickly and there is mounting evidence that this is happening in southern parts of Africa.

“When you look at the mutation map of this variant, it shows that Omicron shares many mutations that Alpha, Betta, Gamma and Delta also share, but it also has a lot more mutations added.”

She explains that it’s unusual for so many mutations to manifest and it could be that the virus was mutating inside an immunocompromised host.

“We must remember that southern parts of Africa are also grappling with an HIV/AIDs epidemic and, with variable Covid-19 vaccination rates compared to the rest of the world, this scenario will allow SARS/coronavirus to keep evolving and it provides a sort of training ground for it to evade immune response and keep transmitting to infect new cells.”

The mutations make vaccines less effective and also mean a higher risk of reinfection of Covid-19, she says.

“The key idea is to find out whether or not vaccine still blocks against severe disease. That’s the key question to try and find out now. If Omicron turns out to have a substantial immune evasiveness that means vaccines will need to be updated and vaccine companies are working on that now.”

Whether drug therapies, which are currently showing positive results for patients with Covid-19, will work on Omicron is another key question.

“Patience is crucial at the moment because these are all questions we are trying to find out as well as whether or not this variant causes more or less severe disease.”

Geoghegan says it will be several weeks before they can see if there’s an increase in hospitalisations and deaths.

“This may be increasing due to overall numbers becoming infected rather than the result of specific infection with this variant. These things take time and a lot of data needs to be gathered before we can conclude those.”

In the meantime, she says overreacting to new variants is a safer course than not reacting at all.

“We really need to understand a little bit more about the biology of this variant before we can conclusively decide whether or not it’s more severe or more transmissible.”

Initial reports of the disease have shown that infection has resulted in mild disease, but Geoghegan says we need to be a bit wary.

“These infections were among young people who tend to have more mild disease anyway. We need a better understanding of the level of severity of the Omicron variant at a population level.”

She says the fact that Omicron is out competing Delta, which has replaced every other variant throughout the world due to its fitness, is concerning.

“That means it’s doing better than Delta and may spread easily in places that have high vaccination coverage or high past infection rates. I think it’s right to be concerned at this moment, but we need to know more.”

Geoghegan says we’re seeing the results of not sufficiently sharing the vaccine around the world and more variants are likely to emerge if nothing is done.

“Southern parts of Africa have the lowest vaccination coverage in the world. South Africa is at about 24 percent vaccinated. Coupled with other issues like the HIV/AIDs epidemic, this is a training ground for new variants to come out of. We need to quickly learn these lessons.”