BA.2 Stealth Omicron Variant Now Dominant as It Sweeps World, WHO Says

The World Health Organization (WHO) has confirmed that the Omicron variant of COVID that is sweeping the globe is dominated by the BA.2 subvariant, the so-called "stealth Omicron."

In a press conference held on Wednesday, technical lead for WHO's COVID-19 response, Maria Van Kerkhove addressed the question of the BA.2 subvariant's dominance, revealing that it now accounts for the vast majority of cases sequenced by experts.

She said: "About 86 percent of the sequences that are available from the last four weeks are this BA.2 sublineage the rest are BA.1. So we are seeing an increasing proportion of BA.2 being detected.

Asked about whether or not we will see BA.2 sweep the world, Van Kerkhove said: "We're seeing that happen right now. This is not a theoretical.

"Omicron is a highly transmissible variant of concern. BA.2 is more transmissible than BA.1 and what we are starting to see in some regions of the world in some countries is an uptick in cases again."

Executive director of the WHO's Health Emergencies Programme, Dr. Michael Ryan, added that as a result of the BA.2 sublineage of Omicron being more transmissible, in some countries the replication rate of the virus had reached 1. This means for every COVID case, one additional person is expected to be infected.

In a press statement released on Tuesday, the WHO said that after consistent decreases in COVID cases since January 2022, March had seen two consecutive weeks of increasing numbers of infection.

The week of March 14 to March 20 had seen a global 7 percent increase in cases in comparison to the week before.

The Centers for Disease Control and Prevention (CDC) said that despite the dominance of BA.2 globally, the predominant Omicron lineage in the United States was still BA.1.1, though the so-called stealth sub-lineage was on the rise.

As of March 19, BA.2 accounted for over a third of COVID cases in the U.S., after a sharp rise to 34.9 percent from its 23 percent share reported by Newsweek the previous week. WebMD said that the stealth subvariant is more widespread in some parts of the country, such as New England where it now makes up about 55 percent of cases, or New York and New Jersey, where BA.2 accounts for 48 percent of new cases

Both Van Kerkhove and Ryan pointed out that the increased spread of COVID is down to both this the transmissibility of Omicron and the BA.2 sublineage and the fact that many countries are now lifting COVID public health and social measures.

Van Kerkhove said: "Whatever variant is circulating if you lift all of the public health measures that we know can reduce the spread of this virus, the virus will take advantage of that.

"I think all of the countries around the world need to learn from each other and really learn that it's the combination of approaches that need to be put in place."

Ryan added that in countries that had focused on vaccinations, with a particular emphasis on the vulnerable, the uptick in cases had not placed pressure on health services and had also not resulted in an increase in deaths.

The WHO confirmed that despite increasing cases, new deaths were decreasing, down by 23 percent during the week ending March 20 compared to the previous week.

Van Kerkhove said the WHO was asking countries to have rational policies and use the tools that can reduce the spread of COVID like masking, physical distancing, improving ventilation, and avoiding crowds as well as increasing vaccination coverage, particularly focusing on those who are most at risk first.

She concluded: "Vaccines are saving lives so it's that dual approach that we are calling for."

Maria van Kerkhove
Maria Van Kerkhove at an interview with Agence France-Presse in Geneva on October 13, 2020.The WHO expert said that so-called "stealth COVID" accounts for 86 percent of cases globally. RICHARD JUILLIART/GETTY