The new worrisome variant we wrote about yesterday, now named Omicron, is roil­ing the world today.

B.1.1.529 was first identified in Botswana, in southern Africa, based on four cases in fully vaccinated people. Another six cases were soon spotted in South Africa, and it was that nation, with its more developed genetic surveillance network, that alerted the world to the potentially dangerous variant. (One case in Hong Kong was directly linked to travel from South Africa.)

The very large number of mutations appearing all at once led researchers to speculate that B.1.1.529 may have emerged in a single patient with an undiagnosed case of AIDS.

Since the online briefing yesterday organized by South African public health authorities, the following de­vel­op­ments have occurred:

• Detections in other countries — Israel has seen one confirmed case of B.1.529, in a traveler from Malawi, and two other suspected cases; according to its new president the country is “entering [an] emergency sit­u­a­tion.” One case has been detected in Belgium. The variant has not been seen yet in the UK or the US.
• WHO actions — The international body urged nations not to impose travel bans (though a number had already done so — see below), saying the world should favor a “risk-based and scientific approach.”

   
  The WHO convened a closed-door meeting in Geneva of an expert panel, which was to hear from sci­en­tists in South Africa about what is known of the new variant. The meeting kicked off six hours ago at 11:00 GMT. The variant has now been given the Greek designation Omicron. The WHO skipped over nu, as I suspected they might, as it could lead to “Who’s on first“-level confusion.

  The WHO has upgraded Omicron to a Variant of Concern.

• Travel bans — The UK was first to impose a ban on travelers from southern African (affecting South Africa, Botswana, Eswatini, Lesotho, Namibia, and Zimbabwe). This was quickly followed the EU’s invocation of a non-binding “emergency brake” on travel from the region. At this writing the list of nations imposing such a travel ban includes Austria, Czech Republic, Germany, Ireland, Israel, Italy, Netherlands, and Singapore. Japan is not yet open to foreign travelers, but that country has imposed a quarantine requirement on nationals returning from the southern African region. Various observers (besides the WHO) are pointing out that travel bans have never been effective in the past at containing the pandemic, and will likely be futile this time because Omicron is already on three continents.
• Stocks plunge — Markets moved sharply lower overnight in Europe and Asia on the variant news. The US stock marked dropped by 800 points in pre-opening trading and at opening suffered the worst Black Fri­day losses on record. Markets were led downward by airline stocks, which are being punished on news of the travel bans. Oil prices have fallen by 10%.

You might want to follow Dr. Eric Feigl-Ding on Twitter. He has been tweeting timely pandemic news since January 2020. Dr. Feigl-Ding noted that Omicron may be 5x more infectious than the original Wuhan strain (vs. a bit less than 4x 1.7x for Delta). Early indications are that Omicron has an R₀ value around 2.

Here is an interview on video with Dr. Fauci from this morning. Good summaries of the developments to date are provided in these videos from the BBC and Deutsche Welle. (Here is DW’s update in text form, if you prefer that.)

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[ Note added 2021-11-26, 14:28 CDT: ] An hour after this post went live the US joined the parade of nations im­pos­ing travel re­stric­tions on eight countries in southern Africa, beginning Monday. The restrictions apply to the six countries listed above for the UK’s ban, plus Malawi and Mozambique.

[ 17:01 CDT: ] In the penultimate paragraph I corrected the relative transmission advantage of the delta variant.

[ 18:35 CDT: ] Here is an Omicron tracker that the creators say will be updated several times per day. Thanks to Mark Gibbs for the tip.