WHO tracking hybrid Omicron subvariant thought to be more transmissible than BA.2

WHO tracking hybrid Omicron subvariant thought to be more transmissible than BA.2
Photo credit: Ani Kolleshi/Unsplash

As the world attempts to move on from the COVID-19, a global health agency says it is monitoring a handful of new mutations of the virus, including one that is believed to be more transmissible than Omicron BA.2.

The World Health Organization told CHEK News Tuesday that it is tracking two new Omicron subvariants called BA.4 and BA.5, which have been added to its variants of concern page — subvariants BA.2 and BA.3 are already on the list.

“These variants have additional mutations that need to be further studied to understand their impact on immune escape potential. Only a few dozen sequences of these variants have been reported from a handful of countries,” WHO said in an emailed statement. “WHO is working with scientists to better understand their current spread as well as any potential impact they may have.”

While little is known about the two new subvariants at the moment, WHO says it is working with scientists to “better understand” the current spread and is urging countries to continue monitoring the virus.

“WHO encourages countries to continue surveillance of the virus and share data promptly on GISAID. This allows WHO and others to have a better understanding of the virus, including its new sublineages.”

WHO is also tracking two new hybrid Omicron recombinants called XD and XE.

XD is a combination of Delta (AY.4) and Omicron (BA.1) and is currently classified by the WHO as a variant under monitoring. WHO says its spread appears to be limited and isn’t anymore more transmissible than other circulating variants.

XE is a combination of the original strain of Omicron and BA.2 that was first detected in the United Kingdom in January. Around 600

Dr. Maria Van Kerkhove, technical lead for WHO’s COVID-19 response, said in a video posted on the organization’s YouTube channel on April 9 that XE is about 10 per cent more transmissible than BA.2.

“Based on an initial analysis of available sequences, there is a slight growth advantage of this recombinant over BA.2, about a 10 per cent increase in transmissibility,” she said.

Omicron makes up almost all COVID-19 cases

Omicron has become the dominant strain of SARS-CoV-2 ever since the original variant (classified as B.1.1.529) first was reported to the WHO last November.

According to WHO’s April 12 situation report, Omicron accounts for 99.2 per cent of all sequences uploaded to GISAID in the past 30 days, while Delta accounts for less than 0.1 per cent.

“The highly transmissible Omicron variant of concern has rapidly replaced all other circulating variants in almost all countries in which it has been reported, and has become dominant globally,” reads the report.

WHO’s report also stated that the number of newly reported cases and deaths declined for a third consecutive week, with over 7 million cases and over 22 000 deaths reported —
decrease of 24 per cent and 18 per cent respectively compared to the previous week.

However, the WHO continues to express concerns that not all countries are testing enough and has warned that the data in their own reports should be “interpreted with caution” because multiple countries are “progressively changing their COVID-19
testing strategies” which is resulting in lower overall numbers of tests performed and, consequently, fewer cases being detected.

“Unless robust surveillance systems are retained, countries may lose the ability to accurately interpret epidemiological trends, implement the appropriate measures necessary to reduce transmission and monitor and assess the evolution of the virus,” reads the report.

In Canada, many provinces, including British Columbia, have limited access to PCR testing and are providing even less real-time data than before. Currently, Ontario, Quebec and Newfoundland and Labrador are the only provinces providing daily COVID-19 data.

Elsewhere, the United Kingdom has moved to a “living with COVID” plan while many European countries have also eased mass testing, making it much harder to know how prevalent the virus is.

Some scientists argue it’s the right time to accept that “living with COVID” means tolerating a certain level of disruption and deaths, as we do for seasonal flu, while others disagree.

“Blinding ourselves to this level of harm does not constitute living with a virus infection – quite the opposite,” Stephen Griffin, a professor in medicine at the University of Leeds, said in an interview with the Associated Press. “Without sufficient vaccination, ventilation, masking, isolation and testing, we will continue to `live with’ disruption, disease and sadly, death, as a result.”

Julian Tang, a flu virologist at the University of Leicester, said although it’s important to have a surveillance program to monitor for new variants and update the vaccine, countries cope with flu without mandatory restrictions or mass testing.

“Eventually, COVID-19 will settle down to become more endemic and seasonal, like flu,” Tang said. “Living with COVID, to me, should mimic living with flu.”

Cambridge University virologist Ravindra Gupta is more cautious, saying that mortality rates for COVID-19 are still far higher than seasonal flu and the virus causes more severe disease, he warned.

“There’s no reason to believe that a new variant would not be more transmissible or severe.”

With files from the Associated Press and the Canadian Press

Nicholas PescodNicholas Pescod

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