Covid – Omicron: why are the XD and XE variants compared to measles, the most contagious disease in the world?

The crisis of Covid-19 is it behind us? Yes, according to the lifting of restrictive measures pretty much everywhere in the world. Not quite if we go by the figures of the contaminationwhose passage of the peak requires confirmation in the coming days.

Another reason for concern: new variants. The circulation of virus indeed allows him to mutate and give birth to new versions. But also two variants to associate. This is particularly the case of XDalso called Deltacron (hybrid of Delta and Omicron), and XE, hybrid of BA.1 and BA.2, “10% more contagious than BA.2”according to scientists from the UK Health and Safety Agency (UKHSA).

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Two variants that are gradually spreading around the world. Several hundred cases of XE have been identified in Englandin Indiabut also in Thailand or even in New Zealand. the variant XDtoo, was detected in France until Australia the last days.

Dr Adrian Esterman, a former epidemiologist for the World Health Organization (WHO), also states in the columns of the Canberra Times that Deltacron is “1.4 more contagious than BA.1”the original Omicron. “This was already the case with BA.2 and it is most certainly also the case with the XE variant. Which makes them very close to measles, the most contagious diseases we know”.

Omicron BA.2 is about 1.4 times more infectious than BA.1. The basic reproduction number (R0) for BA.1 is about 8.2, making R0 for BA.2 about 12. This makes it pretty close to measles, the most contagious disease we know about.

—Professor Adrian Esterman (@profesterman) March 10, 2022

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