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People who have the Omicron Covid variant tend to have symptoms for a shorter period of time, a lower risk of being admitted to hospital, and a different set of symptoms than those who have Delta, the research found.

As the highly transmissible variant of Omicron became dominant towards the end of last year, it emerged that although it is better at dodging the body’s immune responses than Delta, it also produces less severe disease.

Now, a large study has not only backed up the findings, but has confirmed reports Omicron is linked to shorter disease duration and a different set of symptoms.

The study comes just days after the NHS added nine more Covid symptoms to its existing list of fever, new and persistent cough and loss or change in taste or smell. The researchers found that people who had Covid when Omicron was prevalent were about half as likely to report having at least one of the last three symptoms as those who had Covid when Delta was rampant.

“It’s a lesson that we need to be much more flexible in thinking about what the virus is and how it’s going to present itself than we have been, certainly in the UK,” said Professor Tim Spector, co -author of the research from King’s College London, adding that the team showed the government about five months ago data showing that a sore throat replaced loss of smell as a symptom.

The study, which is to be presented at the European Congress of Clinical Microbiology and Infectious Diseases and published in the Lancet, is based on data from 63,002 Zoe Covid study participants.

The researchers matched nearly 4,990 participants who had a confirmed Covid infection between June 1 and November 27, 2021 – when Delta was the most prevalent variant – with 4,990 people who reported an infection between December 20, 2021 and November 20, 2021. January 17, 2022 when Omicron was dominant, with matching by age, gender, and whether they received two or three doses of the vaccine. The experiences of the two groups were then compared.

The team found that participants’ symptoms lasted an average of 6.9 days during the Omicron-dominant period, compared to 8.9 days when Delta dominated, with infections during the Omicron period being related to a likelihood of admission to the hospital 25% lower.

The results suggest that only 17% of people who had Covid when Omicron was dominant lost their sense of smell, compared to 53% when Delta was dominant. However, a sore throat and hoarseness were both more common in the former.

Spector said the symptom recording approach used in the research was an invaluable tool. “[It] should alert us to what to watch for when there is inevitably the next variant,” he said, adding that the action should be faster in the future.

“We need to be much more responsive in public health messaging,” he said.

Dr David Strain, a clinical lecturer at the University of Exeter Medical School, who was not involved in the study, said the results are consistent with what hospitals experienced at the start of the l year when the BA.1 Omicron variant was dominant. But the Omicron BA.2 variant has since taken over – and in his experience the situation has changed again.

“People in hospital stay in hospital longer and staff test positive longer, so it takes them longer before they can return to work,” he said.

The research came as the React-1 study found the average Covid prevalence across England was at the highest level on record. Meanwhile, the UK Health Security Agency reported on Thursday that 15.3% of people aged 75 and over have received their Covid spring booster so far.

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