A top government scientific adviser has denied that many cases of Covid-19 were missed because taste and smell were not designated as symptoms.
England's deputy chief medical officer Professor Jonathan Van-Tam said very few patients experience loss of taste and smell as a lone symptom of the virus.
He said it is often followed by a cough and fever, two of the key symptoms the government has warned people to look out for.
His comments come after the loss of, or noticeable change to, taste and smell were added to the NHS list of coronavirus symptoms, weeks after experts first raised concerns that cases were being missed.
Experts said that an insistence that only fever and cough were the major symptoms had missed thousands of cases of the virus.
When asked whether the UK had missed diagnosis of coronavirus by failing to add loss of taste and smell to the list of symptoms before now, Prof Van-Tam said they were not always the first symptom.
He added: "What I can tell you is from the Public Health England data set, called the FF100 - the first few hundred cases - there are actually 229 cases in there, all laboratory-confirmed Covid, all of whom have been studied in considerable detail and 0.44% reported anosmia (loss of sense of smell) on its own as a symptom. So, the point about anosmia is it doesn't always come as the first symptom.
"Even if it does, it is followed by the cough, the fever and many of the other symptoms I have talked about, referring to the WHO (World Health Organisation) definition.
"So you don't miss those cases.
"The important thing was to work out if this would add any sensitivity to the diagnostic cluster we were using and the answer is that it makes a small, a very small difference, and we have therefore decided to do it."
In Northern Ireland , SDLP MLA Colin McGrath, who sits on Stormont's health committee, urged people to be aware of the new symptoms. "I welcome the statement issued from the chief medical officers across the UK, which contains an important update on Covid-19 symptoms.
"They now consider anosmia, a loss in your sense of smell or taste, as a symptom. If this applies to you, please follow the guidance and isolate with everyone in your household."
Dr Connor Bamford, a virologist at Queen's University, said the additional information would help inform the public.
"We have known for quite some time that loss of taste and/or smell is associated with SARS-CoV-2 infection and Covid-19.
"This symptom may even be rather specific to Covid-19. It is encouraging to see it being added to the list of relevant symptoms that would lead to isolation," he added.
A study led by Professor Tim Spector at King's College London found that 59% of Covid-19-positive patients reported loss of smell and taste, compared with only 18% of those who tested negative for the disease.
Speaking about the findings on April 1, Prof Spector called for the rules to change, saying those with a loss of smell or taste needed to self-isolate.
On Monday he heavily criticised the government's stance so far, saying infected people had been encouraged back to work due to a failure to track symptoms properly.
He said 50,000 to 70,000 people in the UK with Covid-19 were currently not being told to self-isolate, even though they had the virus.