BA.4, BA.5 Surge in Europe: What to Know About the Omicron Subvariants

COVID-19 cases tripled in South Africa in the last week, most of them attributed to Omicron BA.4 and BA.5.

Omicron BA.4 and BA.5 are the newest sub-lineages of the COVID-19 Omicron BA.1 variant. 

(Photo: iStock)

Even as many parts of the world relax COVID-19 restrictions and resume life as it was before the pandemic, some ountries are reporting a fresh surge in COVID-19 cases thanks to Omicron's sub-variants BA.4 and BA.5.

Countries in Europe including France, Portugal, and Germany, among others have been seeing a significant rise in cases. According to experts, this rise may be tied to the new sub-lineages of BA.2 Omicron - BA.4 and BA.5.

The two Omicron subvariants are also close to becoming the dominant variant in the US as well. BA.4 and BA.5 accounted for nearly 35 percent of the positive cases reported last week in the country, according to the US Centres for Disease Control and Prevention (CDC).

To top it off, recent studies have also found that prior vaccination and/or infection with Omicron does not provide immunity from Omicron BA.4 and BA.5.

"It looks like COVID19 may be evolving differently and that we may not need a new variant to cause a new wave of infection. We are seeing this with BA.4 and 5 in South Africa and with BA.2.12.1 on the east coast of the USA."

Dr. Tulio de Oliveira, Director, CERI (Centre for Epidemic Response & innovation)

In fact, Omicron was first detected in South Africa, in November 2021, and quickly became the fastest spreading variant of the coronavirus.

So what do we know so far about Omicron's new sub-lineages BA.4 and BA.5?

What We Know So Far About BA.4 and BA.5 Omicron

First off, BA.4 and BA.5 Omicron are not new variants of COVID-19, they're new sub-lineages of Omicron, i.e., mutations of Omicron.

Dr. Oliveira states that prior infection with BA.1 Omicron is NOT adequate to provide immunity to BA.4 and BA.5 Omicron. This means if you've caught BA.1 Omicron, you can still catch BA.4 and BA.5.

Dr. Oliveira adds that BA.4 and BA.5 could potentially escape the umbrella of BA.1 Omicron and create a new wave.

"The growth advantage of Omicron BA.4 and BA.5 over BA.2 and BA.1 is 0.08 and 0.12 per day," he adds.

The new variants are still being studied for severity, to identify whether BA.4 and BA.5 are more severe than Omicron. Omicron was marked by high transmissibility and low severity.

Dr. Oliveira adds that a possible cause for the new variant's emergence in South Africa could be animal reservoirs and chronic human infections creating an environment that's perfect for virus mutations.

"We are all tired of this virus, but he may not be tired of us. We need now to take seriously the decreasing immunity from previous infections and the data shows that vaccination is much more reliable to maintain immunity than only prior infection."

Dr. Tulio de Oliveira, Director, CERI (Centre for Epidemic Response & innovation)