The emergence and rapid spread of the Omicron Sars-CoV-2 variant feels like a repeat of last year's festive season when many of the world went into lock down to avoid the worst of the Alpha variant wave. The epidemiological and political situations are different from a year ago.
The Omicron wave is a turning point in the epidemic. It feels like a lose-lose deal. If it turns out to be as severe as previous waves, it might normalise harsher measures and make a return to post-pandemic normality very unlikely. If it turned out to be less than feared, this could spell the end of Covid-19 being locked down. It would be difficult to deal with future threats because of the loss of trust in political and public health authorities.
The Alpha and Delta variant emerged in the pre-vaccine phase of the pandemic and spread in largely immunologically naive populations. Increased ability to replicate quickly within their host and higher contagiousness were the reasons for their threat. Both variant were associated with higher hospital admisssion rates. The high contagiousness of the variant allowed it to barge through the first line of the immune defence, although it was not good at escaping immune recognition.
Omicron is not the same. Delta relied on brute force, but it is better at sneaking through immune defences thanks to a number of genes that it acquired. The ability of neutralising antibodies to bind to it is reduced. It spreads by re-infecting previously immunised hosts.
In the first week of December, the number of Omicron cases in the province of South Africa increased by 400%. The peak of the outbreak is expected within a week. The epidemics in other parts of South Africa are slowing down despite no measures being taken to suppress transmission.
Omicron cases are doubling every two to three days in the UK. There is a lot of uncertainty about the virulence of Omicron. Evidence from South Africa suggested Omicron might be milder. All infections start with mild symptoms and there is a time lag before severe disease develops. The hypothesis of the Omicron wave being significantly milder is becoming more plausible as more data arrives. The reported deaths and hospitalisations in South Africa have remained far below previous waves.
The interaction with the host of a pathogen is what makes itulence. Most people on Earth have high rates of immunisation. Omicron can be bypassed by neutralising antibodies, but it is still recognised by T-cells, who do the heavy lifting to control infections that can't be averted. The vaccine's efficacy against severe symptoms caused by the variant is largely unchanged and a recent third dose seems to provide significant protection against infections.
No government can allow healthcare services to be overwhelmed by the large peak of cases anticipated over the coming weeks. A case for harsh measures based on the protection of healthcare services might be less well received by many nearly two years into the Pandemic because of the uncertainty around the severity of Omicron.
It's difficult to sell a lockdown to Omicron as it comes with no obvious endpoint.
The population generally accepted the first lock downs in early 2020 as a temporary measure in the face of an exceptional threat. Many felt that the epidemic could be delayed until the population could be vaccined. It's not clear what the end goal is of a lock down to deal with Omicron, but it's possible that it will allow for a small increase in the number of people who are vaccined or boosted before the peak of the wave.
How to respond to the Omicron wave is a big challenge for public health authorities. The World Health Organization has criticized western governments for imposing travel bans against African countries. Travel restrictions have lost their effectiveness due to the rise in local community transmission of Omicron. Increasing the rate of vaccine should make a difference in terms of morbidity and mortality over the coming months, but time is running out, given the rapid increase in daily Omicron case numbers. Many governments are taking coercive measures, which could quickly escalate to compare with previous lockdowns.
The population's willingness to follow the rules will determine how effective those measures are. Adherence may be far lower if there is no sense of fear or trust.
If Omicron's impact is especially rough or mild, it could be a huge deal. Even an intermediate outcome could cause more resentment and deep divisions in society.
Francois Balloux is the director of the Genetics Institute.
