Omicron sufferers may hear that they have the mutant variant before they feel it.
Since coronavirus began sweeping across the globe two years ago, those infected by the potentially deadly bug have reported dozens of side effects.
Like Alpha and Delta before it, Omicron – the now dominant strain in the UK – causes a specific array of symptoms.
Many who catch the highly infectious version of Covid-19 have reported that the first tell-tale signs can be heard rather than felt.
They have found themselves with a croaky, husky voice despite not having sung or shouted.
Often this side-effect, which is caused by a scratchy rather than sore throat, comes before other symptoms such as a bunged up nose, dry cough and pain in the lower back.
Dr Angelique Coetzee, the South African doctor who first alerted authorities to the Covid variant, has said muscle aches, fatigue, a scratchy throat and night sweats are common Omicron symptoms.
Scientists running the Covid Symptoms Study app at Zoe and Kings College found the top five Omicron symptoms were a runny nose, headache, fatigue (either mild or severe), sneezing, and throat issues.
They later found that only 50% of people with Omicron were impacted by the three classic coronavirus symptoms of a fever, cough and loss of sense of smell or taste.
Among the other symptoms that have been reported by those infected with Omicron is a loss of appetite, brain fog and congestion.
Paying attention to your body is important now that the coronavirus situation in the UK is poised on a knife edge.
On the positive side of things, an Imperial College study found people who caught Omicron are up to 20 per cent less likely to be admitted to hospital than those who get Delta.
It also found that the chance of having to stay in the NHS overnight was even lower, with a reduced risk of up to 45 per cent.
However, the number of infections is now so high that hospitals could see pressures similar to last January.
Advisers on the Scientific Pandemic Influenza Group on Modelling, Operational sub-group have told the Government this could be the case even with new restrictions and the reduced potency of Omicron.
Hospitalisations are now rising steadily in places where Omicron first got a foothold in the country.
In London there were 386 new Covid hospital admissions on December 22.
While this is far fewer than the 850 admissions recorded on one day in January last year, it marks a 92% rise on the figure last week.
The last time the Government published case data, on December 24, a record 122,186 infections were reported.
On December 20, when nationwide hospital admissions data was last logged, there were 1,171 new Covid patients in hospitals across the UK.
That is a rise of slightly more than 200 compared to the same day the week before.