Almost two years into a pandemic horrible uncertainties remain, yet “the knowns” about how Covid-19 behaves are considerable. Responsiveness to emerging variants is much improved.

The Omicron variant arising in countries of southern Africa has rung alarm bells much more promptly, while better international collaboration between scientists and health authorities means a global response is being scaled up rapidly – even if travel bans are of limited benefit.

This is familiar territory, given the way Alpha and Delta variants behaved, but precautionary measures kicked in a lot quicker. Compared with early Covid waves, the scientific evidence for the effectiveness of masks, social distancing, reducing contacts and ventilation has strengthened.

Hospital Report

These are sensible precautions even if they will not stop Omnicron spread. They will slow it, generating time to learn more about the variant while increasing booster uptake.

Coalition leaders to discuss Omicron variant with Nphet on Monday

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Q&A: As people queue for booster vaccines, when can I get mine?

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Third case of Omicron coronavirus variant detected in UK

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Omicron symptoms mild so far, says South African doctor who discovered it

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This is prudent as the Northern Hemisphere faces into winter when flu and other respiratory viruses are prevalent. Clearly, another surge of Covid cases risks tipping health services over the edge.

Omicron is likely to be distributed widely across the planet – including Ireland – already and so a counter strategy with that in mind is wise.

What we know about the Omicron variant?

This variant has a large number of mutations: 50 overall; 10 on “the receptor binding domain” of the spike protein. This suggests it emerged from a persistent infection in an immunocompromised person.

A high number of mutations does not mean the variant poses a greater threat, though it may make it more likely to look different to the immune system. If it fails to recognise it, there may be “immune escape” with people who have recovered from a previous Covid-19 infection, or who have been vaccinated, failing to recognise the virus and becoming ill despite prior immunity.

The variant is rapidly increasing in Africa, suggesting it is more infectious than previous strains, or that there is less immunity to it. Even if vaccines work just as well, we would need to have more people vaccinated and immune in order to achieve herd immunity to a more infectious strain.

What is unknown about Omicron as of yet?

The main concern is we don’t know how transmissible it is, and if vaccines will be less effective especially in curbing severity of disease.

Frantic efforts are being made to answer the transmissibility question. So far, current vaccines have worked well against the predominant Delta variant to reduce severe disease and death – though they are less effective in preventing infection/reinfection.

If vaccines are shown to be less effective, they can be adjusted within days but new versions will require clinical evaluation and regulatory approval.

The other big unknown is if there are particular circumstances associated with where the variant has emerged. Immunisation status in Ireland and much of Europe is more favourable than in Africa, where there has been low vaccine uptake.

So far, Europe is only seeing “imported cases”. When there is local spread within a population – not linked to international travel – we will see how much transmissibility there is in a typical European population.

Will this new variant change this balance? Data gaps mean that answer is not yet available, so reimposing restrictions is warranted.

One stark indication, however, stands out. The world has done a poor job in ensuring poorer countries are vaccinated. In that scenario, conditions are perfect for new more dangerous variants to emerge.