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Opinion: Omicron is sneaky. It could be fatal for us – or for our faith in government

12 December 2021

The week ahead will be pivotal as we track the spread of the new variant and discover its potential legacy, says Professor Francois Balloux (UCL Genetics Institute).

Professor Francois Balloux

The emergence and rapid spread of the Omicron Sars-CoV-2 variant feels like a flashback to last year’s grim festive season when much of the world went into lockdown to avert the worst of the Alpha variant wave. But though the sense of eerie, impending doom feels familiar, the epidemiological and political situations are different from one year ago.

The Omicron wave represents a key turning point in the pandemic. But no plausible outcome looks particularly auspicious – it feels largely like a lose-lose deal. If it turns out to be roughly as severe as previous pandemic waves, it might normalise harsh mitigation measures and render the prospect of a return to post-pandemic normality fairly remote. If it turned out to be milder than feared, this could spell the end of lockdowns with Covid-19 on its way into endemicity. The cost would be a loss of trust in political and public health authorities, which may make it difficult to deal with future threats.

Omicron is a different beast to the Alpha and Delta variants, which emerged in the pre-vaccine phase of the pandemic and spread in largely immunologically naive populations. Their threat came from the increased ability to replicate quickly within their host and their higher contagiousness. Both variants were associated with higher hospital admisssion rates and deaths. However, neither variant was good at escaping immune recognition, although each could cause occasional “breakthrough infections” in immunised people, with high contagiousness allowing these variants to barge through the first-line immune defence.

Omicron is different. Rather than just relying on brute force, as Delta did, it is far better at sneaking through immune defences, thanks to a number of mutations that it acquired in key regions of its spike protein. These reduce the ability of neutralising antibodies to bind to it. As such, it spreads primarily by (re-)infecting previously immunised hosts.

The centre of the Omicron outbreak was Gauteng province in South Africa, which experienced a dramatic rise of nearly 400% in the number of cases in the first week of December. The Gauteng outbreak seems to be receding with its peak expected within a week or so. Other regions of South Africa also show signs of their epidemics slowing down despite no measures having been taken to suppress transmission.

Many countries are seeing rapid rises of Omicron cases, which are recorded as doubling every two to three days in the UK. But there is considerable uncertainty about the virulence of Omicron. Early, largely anecdotal, evidence from South Africa suggested Omicron might be milder. Such data has to be interpreted carefully as essentially all infections start with mild symptoms and there is a time lag before severe disease develops. As additional data has landed in the past two weeks, the hypothesis of the Omicron wave being significantly milder becomes increasingly plausible. Reported deaths and hospitalisations in South Africa, in particular those requiring intensive care or ventilation, have remained far below numbers recorded during previous waves.

Virulence is not just a property of a pathogen but of the interaction with its host. Most populations on Earth have acquired high rates of immunisation through vaccination and prior infection. While Omicron can largely bypass neutralising antibodies, it remains well recognised by T-cells, which do the heavy lifting to control infections that can’t be averted. As such, vaccines largely retain their efficacy against severe symptoms caused by the variant and a recent third dose still seems to provide significant protection against infection.

Irrespective of the relative virulence of Omicron, the large peak of cases anticipated over the coming weeks is expected to add further stress to healthcare services, which no government can allow to become overwhelmed under its watch. A case for harsh mitigation measures based entirely on the protection of healthcare services might be less well received by many nearly two years into the pandemic, in particular given the uncertainty around the severity of Omicron.

The first lockdowns in early 2020 were generally well accepted by the population as a temporary measure in the face of an exceptional threat. Many felt that later lockdowns were justified as a means to delay the epidemic until the population could be vaccinated. A lockdown to deal with Omicron may be a more difficult sell; it comes with no obvious endpoint besides its objective to “flatten the curve” and allow for a marginal increase in the number of people vaccinated or boosted before the peak of the wave.

How to respond to the Omicron wave poses extreme challenges to political and public health authorities globally. So far, western governments have enforced early, harsh travel bans against African countries, which have been widely criticised, including by the World Health Organization. Given the rapid rise in local community transmission of Omicron, those travel restrictions have lost all efficacy they might have had early on. Increasing the rate of vaccination, including third doses, in particular for those most at risk, should make a real difference in terms of morbidity and mortality over the coming months, but time is rapidly running out given the remarkably fast increase in daily Omicron case numbers. Many governments are also taking more intrusive or coercive measures, which could rapidly escalate to compare with previous lockdowns.

How effective those measures are at reducing viral transmission over the coming weeks will largely depend on the population’s willingness to follow the rules. In the absence of a clear sense of fear and a possible loss of trust, adherence may be far lower.

As I noted, Omicron’s legacy could be huge if its impact proves to be especially rough or mild. But even an intermediate outcome might cause additional resentment and further the deep divisions in society.

This article first appeared in The Guardian on 12th December 2021.