World Health Organization warns of a new recombinant variant, the Omicron XE hybrid, first detected in the UK.
First flurona, then deltacron, and now Omicron XE, it seems like hybrid variants are on the rise across the world. According to the World Health Organization’s (WHO) latest weekly report, the XE hybrid variant first emerged in the UK on January 19th of this year. Since then, approximately 600 sequences of the recombinant variant have been reported in the country. Furthermore, compared to stealth Omicron (BA.2), XE has shown a 10% higher transmission rate. However, current data is too limited to draw conclusions on the variant’s severity, transmission, or disease characteristics.
The UK Health Security Agency (UKHSA) is closely monitoring all recombinant variants in the country. According to Chief Medical Advisor, Professor Susan Hopkins, several recombinants have emerged in the past and have died off without causing any harm. Therefore, health authorities have not stated the variant as a public health concern.
The Omicron variant is currently the dominant strain worldwide, accounting for 99.8% of global cases. Among Omicron lineages, the BA.2 (Stealth Omicron) variant has accounted for 93.6% of new cases. According to the Centers for Disease Control and Prevention (CDC), the Omicron subvariant has also become the dominant strain in the United States. Moreover, the surge in BA.2 cases has led to the renewed implementation of COVID restrictions across China, Hong Kong, and South Korea.
What Are Recombinant Variants?
The XE variant is a recombinant of the Omicron subvariant BA.1 and BA.2. However, XE is not the only hybrid variant to raise concerns during the pandemic. Previously researchers had reported the discovery of deltacron, a recombinant of Delta and Omicron strain. Although it was initially considered a lab error, scientists have since confirmed its existence. Also called XD, the variant first emerged in France in December of last year, but has since not spread at a concerning rate.
But the real question remains: what is a recombinant variant?
According to scientists, recombinant viruses are a common occurrence as viruses evolve with time. It mostly emerges when an individual is simultaneously infected with two or more variants. As a result, the variants interact within the person’s cell, mixing their genetic material and forming a new recombinant strain.
Since the start of the pandemic, several recombinant SARS-CoV-2 variants have emerged, such as XA, XB, XC etc. However, they mostly died off without causing any damage. According to WHO, the high global transmission of SARS-CoV-2 means that further recombinants will emerge in the future. Therefore, they are closely monitoring both XD (deltacron) and XE lineages to provide further updates on the new strains.
The UKHSA is currently examining three recombinants: XF, XE, and XD. Both XD and XF are a combination of Delta and Omicron. While XD cases have mostly occurred in France, XF has caused a little over 30 cases in the UK. In comparison, more than 600 XE cases have emerged in the UK since the 19th of January. Furthermore, countries such as Canada, Japan, China, and Thailand have also reported cases of the XE recombinant.
Reduced SARS-CoV-2 Testing Threatens Detection of XE Hybrid Variant
However, despite emerging cases, experts don’t believe the variant is a cause for concern just yet. Although it is possible the variant can be more transmissible, it might not be as severe. Nor can one predict its effect on vaccine effectiveness. Therefore, the WHO has not yet labelled it as a variant of concern.
According to WHO, there was a 16% decline in new COVID-19 cases between 29th March to 3rd April. The number of weekly deaths also saw a sharp decline, approximately 43%, as compared to the previous week. This global decrease in COVID-19 cases has led various countries to alter their testing strategies. For example, countries such as the United States have closed down several free COVID-19 testing centers; thus, resulting in a lower number of tests performed. In the recent report, WHO reported a 12% reduction in the weekly collection and submission of sequences. Therefore, it believes that the decreased reporting will ultimately affect genomic surveillance of new variants
For now, the best way to predict the course of the variant is closely monitoring its spread and continue to follow COVID-19 protocols such as regular handwashing, practising social distancing, and wearing masks. Since the XE hybrid variant contains the BA.2 strain, scientists believe that it is highly unlikely the recombinant strain will cause considerable damage to vaccine effectiveness. Therefore, they recommend people receive their complete vaccination and booster doses to reduce the chances of co-infections and prevent the emergence of any more recombinant strains.
Source: World Health Organization