COVID-19: Investigations underway as Omicron variant BA.2 spreads worldwide

A variant of Omicron that is more difficult to detect through testing and spreads more easily has appeared, says an epidemiologist and the World Health Organization.

According to the WHO, the BA.2 variant is a spinoff of the BA.1 (Omicron) variant that appeared late last November and has now taken over from the Delta variant.

Omicron is more transmissible because it does a better job of attaching itself to cells in the nose and is also better able to evade vaccines in the body.

In B.C. all COVID-19 cases are considered to be BA.1 Omicron — which can be identified from a PCR test. The B.C. Ministry of Health did not confirm by deadline whether any cases of BA.2 had appeared in the province.

In a WHO technical briefing on Omicron published on Friday, it was stated “while the BA.1 (original) lineage has previously been the most dominant, recent trends from India, South America, the United Kingdom and Denmark suggest that BA.2 is increasing in proportion.”

As a result, last Friday the U.K. Health Security Agency marked BA.2 a variant under investigation.

The #OmicronVariant sub-lineage known as BA.2 has been designated as a variant under investigation. The number of BA.2 cases is currently low, with the original Omicron lineage, BA.1, still dominant in the UK and further analyses will now be undertaken. https://t.co/254m2rwJN5

— UK Health Security Agency (@UKHSA) January 21, 2022

Katelyn Jetelina, an epidemiologist at UT Health Science Centre in Houston, published a “COVID-19 State of Affairs” report on Jan. 24 that said case patterns could change worldwide because of the emergence of BA.2.

“BA.2 lacks the (69-70) spike mutations. This is important, because it means, unlike with BA.1, BA.2 doesn’t have a special signal on PCR tests to tell labs that it is Omicron. All tests now need to go to genetic sequencing for variant identification,” Jetelina wrote.

Genetic sequencing takes time and is costly, so it cannot be done en masse on samples.

Jetelina wrote that studies out of the U.K. showed BA.2 was more transmissible than BA.1 but by way less than BA.1 was compared to Delta.

“On Friday, the U.K. labelled BA.2 a variant under investigation as it’s doubling every four days there which equates to a 120 per cent growth advantage over BA.1. Variant under investigation is the least severe variant classification, but still a signal that we need to pay attention. BA.2 has already started to take hold in places like India, Philippines, Netherlands, France, and Denmark,” Jetelina wrote.

“The consistency of BA.2 growth across several countries means that it’s more transmissible than BA.1. But it’s likely nothing like the huge transmissibility jump we saw from Delta to Omicron.”

She said that early data out of Denmark showed no disease severity difference between the two Omicrons.

“We know this virus will mutate. And BA.2 is an example that it’s doing what we expect. We should keep an eye on this, but I’m not too concerned right now. I’m more concerned about another variant popping out of nowhere like Omicron did.”

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The WHO briefing stated that what caused BA.2 to transmit more effectively than BA.1 — and what its properties were — were under investigation and remained unclear at this point.

The briefing went on to say that current evidence consistently shows “a reduction in neutralizing titres against Omicron in individuals who have received a primary vaccination series or in those who have had prior (COVID-19) infection.”

This means the Omicron is better able overcome vaccines than the Delta variant was — so vaccines are less effective against Omicron — and is able to reinfect people with COVID-19.

“Early data suggest that the effectiveness of studied vaccines is significantly lower against Omicron infection and symptomatic disease compared to Delta, with homologous and heterologous booster doses increasing vaccine effectiveness,” the briefing stated.

“Despite this, followup time after booster doses for most studies is short, and there is evidence of waning of vaccine effectiveness in months following booster doses.”