Spread of Omicron variant must be curbed – and fast

If pandemics were easy this one would be long over. Instead, the Covid-19 pandemic has resulted in repeated waves of infection, each one posing a slightly different version of the same challenge.

This time, it is the Omicron variant that threatens to spoil Christmas and clog up the health service with sick patients.

The National Public Health Emergency Team’s (Nphet) proposals to deal with Omicron, particularly the plan to close pubs and restaurants from 5pm each day, were met on Friday with howls of outrage.

The proposals prompted plenty of complaint, along the lines of “how come I can do X, but can’t do Y?” or “how is it safe to do X before 5pm but not after?”

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The commentary was heartfelt and understandable, given the body-blow such a change would represent for many people in the hospitality industry.

But it also missed the point. Something has to be done to curb the spread of Omicron – and fast. Countries all over Europe, and beyond, are facing the same challenge, and responding in ways similar to what Nphet is proposing.

We throw around expressions such as “exponential growth” and “doubling time” sometimes without thinking about what they really mean.

Cases of Omicron are doubling in less than two days in the UK and Denmark. In Ireland, the variant has gone from 1 per cent to over 30 per cent of cases in a week. This kind of growth has to be checked.

Small fraction

It is true that the amount of serious illness matters more than case numbers, but Omicron seems to be so different and so much more transmissible than its predecessors that it warrants action. Even a small fraction of a very big number is itself a big number.

Deciding exactly what to do now is hampered by our lack of knowledge about this phenomenon. That in turn suggests we need to make decisions fast, while building in an element of caution for things turning out worse than expected.

As England’s chief medical officer Chris Whitty said during the week: “There are several things that we don’t know [about Omicron], but all things that we do know are bad.”

If you’re worried about a rapidly spreading disease, one that thrives on human contact, you limit its growth by clamping down on that contact. And you start with high-risk areas involving large numbers of people, or people occupying confined spaces, or people not following other public health measures due, for example, to the disinhibiting effects of alcohol.

Superspreading

Omicron has already been implicated in a number of recent superspreading events, such as a party in a restaurant in Norway where more than half the 120 people present contracted the virus, or a nightclub in Australia with 200 cases. There’s no reason to believe events like these won’t happen in Ireland.

As Omicron becomes dominant here over the next week, the surge will be amplified by increased social contact over Christmas, according to chief medical officer Dr Tony Holohan.

Nphet's previous predictions have generally proved to be on the pessimistic side, but this was generally because they prompted changes in behaviour

Most of us who get infected will experience only a mild illness, of course, though the latest indications from the UK do not support early hopes that Omicron might be less severe than earlier strains.

But with anything between 8,000 and 30,000 cases a day possible, according to Nphet’s projections, the result will be hundreds and possibly thousands of hospitalisations. On top of this, large numbers of health staff will become unavailable due to infection or being a contact.

Nphet’s previous predictions have generally proved to be on the pessimistic side, but this was generally because they prompted changes in behaviour and/or the imposition of restrictions that altered existing dynamics.

Critics can rightly point to the wide variation between the best and worst case scenarios laid out by officials, but this is due to the gaps in our knowledge about the new variant.

Evade immunity

We know Omicron spreads rapidly, probably due to its ability to evade immunity and because it is intrinsically more transmissible. But as Dr Holohan in his letter to Government explains, we don’t know the relative contribution of these two mechanisms.

If it spreads largely by evading the body’s immune defences, this will likely result in milder cases and fewer hospitalisations. But if it is simply more infectious, a larger fraction of infected people will become seriously ill.

There are at least indications the Omicron wave, though high, could be short-lived. If so, the measures agreed by Government might not need to apply for very long.

So while this might seem like Groundhog Day, we are still in a far better position than we were a year ago. The vast majority of us are protected through two or three doses of vaccine, but that still leaves the risk to the health service of being unable to meet the demand from sick Covid-19 patients.