The variant took hold in December, after originally being identified by South African scientists in November.
It has since caused record infection figures in the UK. Daily cases have passed 200,000 on several occasions, and hospitalisations have doubled in the last week – though the spike in hospitalisations and deaths is well below the jump in infections.
It is now common knowledge that it is possible to catch Covid-19 twice – but what about getting the Omicron variant twice? Here is everything we know.
Is it possible to get the Omicron variant twice?
At present there is not enough data to tell whether people can get reinfected with Omicron.
This is because most public health bodies define reinfection as two positive test results for the same individual 90 or more days apart.
Residual signs of Covid infection can show for up to three months on a PCR test, so the only reliable way of talking about reinfection is to include a 90-day window between positive tests.
The first Omicron case was only identified in the UK on 27 November, so there has not been enough time to reliably work out whether it is possible for people to get reinfected.
Omicron was first reported to the World Health Organisation (WHO) from South Africa on 24 November — just three days before it was first identified in the UK – so there is no reliable data from there either.
However, the UK Health Security Agency (UKHSA) told i it was “definitely possible” to get Omicron more than once, in the same way that it is possible to get any Covid variant twice – but that UK studies have yet to look into how likely this is.
Dr. Amesh Adalja, senior scholar at Johns Hopkins Centre for Health Security in the US, agreed: “It’s unclear, at this point, what level of immunity occurs after an Omicron infection. I suspect over time, yes, you probably can get reinfected. But we don’t have that data yet because Omicron has only been around since October/November.”
Can you get Omicron after being infected with a different variant?
Yes. UK studies into Omicron have also suggested that previous Covid infection provides poor protection against the new strain.
Researchers at Imperial College London found that the Omicron variant largely evades immunity from past Covid infection or two vaccine doses.
A study of all the PCR test-confirmed Covid cases in England between 29 November and 11 December concluded that patients who had already contracted coronavirus only had around 19 per cent protection against Omicron.
The figure was roughly in line with two doses of a Covid vaccine, which scientists estimated were as much as 20 per cent effective against the new variant.
Ministers noted that the data showed the importance of the booster jab, which is thought to provide protection against around 55 to 80 per cent of symptomatic cases.
Analysis by the UKHSA published in December showed that around one in 10 people with the Omicron variant in England had previously contracted Covid-19.
How serious is the Omicron variant?
Studies have shown that Omicron typically causes less severe illness than previous Covid variants.
Research published by the UKHSA in December suggested that someone infected with Omicron is between 31 per cent and 45 per cent less likely to attend A&E and 50 per cent to 70 per cent less likely to be admitted to hospital than an individual infected with the Delta variant.
However, the WHO has warned against calling the strain “mild”.
WHO director general Tedros Adhanom Ghebreyesus said: “While Omicron does appear to be less severe compared to Delta, especially in those vaccinated, it does not mean it should be categorised as mild.
“Just like previous variants, Omicron is hospitalising people and it is killing people.”