COVID-19: how do Omicron symptoms compare to other variants?

First identified in South Africa on 24th November 2021, the new COVID-19 variant known as Omicron has fast become a variant of concern in the UK and worldwide. How do the symptoms of Omicron compare to other COVID-19 variants?

What COVID-19 variants are there in the UK?

Since it was identified in India in early 2021, the Delta virus variant of coronavirus (COVID-19) has become responsible for most COVID-19 infections worldwide. In the UK, Delta remains the dominant variant with the highest rate of infections. Omicron however, although only discovered in South Africa on 24th November 2021 (and declared a variant of concern by the World Health Organization two days later), appears to have a faster transmission rate.

UK Health Security Agency - Top COVID-19 variants in England

Accurate as of 10th December 2021:

  • Delta.
  • Omicron.
  • Alpha.
  • Beta.
  • Gamma.

Omicron prevalence in the UK

Accurate as of 13th December 2021:

The new COVID-19 variant Omicron has a large number of mutations, and has prompted countries around the world to impose travel bans on southern African countries as well as to reintroduce domestic restrictions.

How do Omicron symptoms compare to other variants?

The main symptoms of earlier COVID-19 variants include:


Delta, the current dominant variant in the UK, can trigger these symptoms as well as the following:

As Omicron is such a new COVID-19 variant, experts advise that there are currently not enough data to confirm any new COVID symptoms with any certainty.

With this in mind, there is some early evidence to suggest new COVID variant symptoms. Angelique Coetzee, a South African doctor who has treated patients with Omicron, records fatigue and a high pulse among 'unusual' COVID-19 symptoms. A high temperature, cough, and sore throat were symptoms recognised for other variants and were also reported for Omicron.

Are Omicron symptoms milder?

According to Professor Rodney E. Rohde, a professor of clinical laboratory science and an infectious disease specialist at Texas State University, "At this time [Dec 8, 2021], the Omicron variant is showing less severity in infected patients."

However, Rohde stresses that there is a lack of data and many influential variables to account for at this early stage: "Experts must allow for time [several weeks or more] to determine if it is more severe an infection compared to other variants.

"We also need to remember that the information coming out of South Africa is not a complete picture, since many of the reports of infection are younger individuals. In other words, we need a larger and more diverse sample set to be sure."

As of 14th December, official figures confirm one death from Omicron. The health secretary Sajid Javid reminded the public that hospitalisations and deaths lag infections by around two weeks.

The World Health Organization (WHO) also emphasises that it is not yet clear whether these new COVID-19 variant symptoms cause more severe disease compared with other variants.

Professor Shabir Madhi of the University of the Witwatersrand in Johannesburg, South Africa, pointed out in an interview with the Global Health Crisis Coordination Centre that the South African experience may be unrepresentative. In Gauteng province, the epicentre of the South African outbreak, up to 72% of the population have had previous COVID-19 infection after three earlier waves of the virus. The resultant immune response may be offering protection against severe illness.

WHO also warns that all COVID-19 variants can cause severe symptoms, illness, or death, especially for the most vulnerable groups.

Does Omicron have higher transmissibility?

"Most of the data are from South Africa and are showing that Omicron has a high degree of transmissibility," says Rohde. "But experts and scientists need more time to determine exactly how infectious it is compared to the Delta variant as well as other variants."

Again, a larger pool of data is needed to determine if Omicron does in fact spread at a faster rate. This said, data are being collected and analysed daily as cases rise in the UK and this picture is quickly forming.

According to the latest UK Health Security Agency (UKHSA) report on 13th December 2021, if Omicron continues to grow at the present rate it is predicted to become the dominant variant in the UK within weeks or possibly days. The UKHSA estimates that over one million people will be infected in the UK by the end of the year.

How can the COVID-19 Omicron variant be prevented, diagnosed and treated?

At present, official UK public health advice remains the same for all current COVID-19 variants. The headlines for prevention advice are as follows:

Do PCR tests work for the COVID-19 Omicron variant?

WHO advises that PCR tests continue to detect all COVID-19 infections, including the Omicron variant. However, research is currently underway to determine if this new variant has any impact on other types of tests, including rapid antigen detection tests.

Does vaccination offer protection against the COVID-19 Omicron variant?

Early evidence suggests that Omicron may compromise, but not completely eliminate, immunity protection through vaccination. These initial laboratory studies from South Africa, Germany and Sweden are preliminary and more evidence is needed.

A UK Health Security Agency report suggests that booster vaccination offers up to 75% protection against symptomatic infection with the Omicron variant. It is hoped that protection against more severe infection provided by booster doses will be even higher.

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