On 26 November the WHO decided to call the B.1.1.529 variant of Covid-19 Omicron, the 15th letter of the Greek alphabet. Which we know as O. They also decided that it was a “variant of concern”. Saying: “In recent weeks, infections have increased steeply, coinciding with the detection of B.1.1.529 variant. The first known confirmed B.1.1.529 infection was from a specimen collected on 9 November 2021.”.

Compared to the original Wuhan version this Omicron variety has about 50 mutations and about 30 of these are in the virus “spike”. This is important because the spike it uses to attack our cells. And it is the spike proteins that the existing Covid-19 vaccines teach our immune system to recognise.

So what does this mean for the vast majority of us who are conscientious and have had the vaccines? It probably means that we are less protected from catching the disease. But still have good protection from becoming seriously ill, hospitalised or dying. Likewise those who already had Covid-19 will probably be susceptible to re-infection, but more mildly.

What is important with new Covid-19 strains is how contagious they are. The Alpha (or Kent) variety was 150% more contagious than the original Wuhan version, so supplanted it, spreading around the world. Then Delta (or Indian) was 40% to 60% more transmissible than Alpha and so replaced it globally as the dominant strain. Omicron was detected when the number of cases in South Africa’s Gauteng province started rising disproportionately. When the virus responsible was sequenced Omicron was revealed. This incident means that Omicron is yet more contagious than Delta and could supplant it to become the most prevalent version.

Also important is how nasty it is. Obviously for each individual that will depend if they are vaccinated, how old they are and upon comorbidities such as diabetes, obesity and vitamin D deficiency. But already we are getting reports from South Africa that it is less severe than previous strains. Dr Angelique Coetzee, a GP in Pretoria, has treated a number of Omicron patients. She says: “Their symptoms were so different and so mild from those I had treated before”. The main symptom she sees is intense fatigue and there is no loss of sense of taste and smell, which previous strains have caused.

Already Omicron has spread all over the world. Countries that haven’t reported it just haven’t detected it yet. Easy when most cases are likely to be symptomless or very mild. Countries globally have banned flights from a number of South African countries. Israel has closed its borders completely and many countries have stiffened their border controls. The UK, for instance, has mandated a day 2 PCR test for all travellers with self isolation until a negative result is received. But really this is bolting the stable door after the horse has bolted. All they can achieve is to slow down the spread of the virus. Buying us more time to learn about this strain.

So what do we do next? If Omicron is as mild as reported (especially amongst the vaccinated and previously infected) and will not overwhelm health services then there is a very good case for doing precisely nothing. Letting it spread through society, rapidly creating herd immunity. Then it will go away and will eventually be replaced by another strain. This would save us from the enormous societal and economic problems that previous government measures have caused.

If governments want to slow the spread down they can reintroduce mask wearing (proven to be effective), prioritise working from home and prevent large gatherings of people, such as soccer games and cinemas. If they want to protect vulnerable people then they should isolate them. Not impose restrictions on the huge majority who are not vulnerable.

All the vaccine companies will already know the genetic sequence of Omicron and by now will have already designed a vaccine for it. This time hopefully more effective against future strains. Whether it is worth putting these new vaccines through testing, licensing and production is another matter. It would probably take about three months and cost a few billion. It might just be worth waiting and using the knowledge when designing next winter’s booster.

Finally Omicron could be a good thing. In the short term it could replace Delta as the dominant strain and, being far milder, cause less harm. Longer term it could point the evolutionary path of Covid-19 into becoming a mild endemic disease, like the Common Cold, or ‘Flu.