THE primary symptoms in patients infected with coronavirus (COVID-19) included fever, cough, sore throat and difficulty in breathing.
Doctors said a complete loss of smell (anosmia) and taste may be early warning signs of coronavirus which most patients said they encountered before other symptoms appeared.
The World Health Organization said other indicators include fatigue, aches and pains, a blocked nose, sore throat and diarrhea.
Many people appear not to develop any further signs, making a full recovery without even realizing they had the virus. They are thought to be mostly healthy young adults whose immune systems react sufficiently to the virus to contain it within the nose, preventing it spreading to the lungs, where it can use potentially fatal pneumonia.
New data gathered by ENT (ear, nose and throat) doctors in UK, said the inability to smell — and often taste — may be the very first symptom and can start within hours.
Doctors are advising patients with no obvious explanation for their loss of smell to self-isolate for at least seven days in case they have COVID-19, even though this is not the current government recommendation.
In South Korea, 30 per cent of patients tested positive for COVID-19 have had anosmia as their major presenting symptom.
Up to 40 per cent of cases of anosmia are caused by a viral infection of the airway as a result of a cold, flu or sinusitis — an infection of the narrow tubes in the nasal cavity. But it usually develops after an infection.
Meanwhile, smokers are also at greater risk of contracting the coronavirus.
Smoking - a killer habit known to cause cancer - damages lung health and raises the risk of other respiratory infections, such as the flu.
Scientists discovered that critically ill patients are more likely to be smokers.
Chinese researchers found a quarter of infected patients who needed life support or died were smokers.
Another study by experts in Wuhan - where the pandemic began - also discovered smokers were more likely to see their disease progress.
But another team from the Chinese city was mystified after finding smokers were less likely to catch the deadly virus in the first place. In another twist, it also found smokers were more likely to suffer severe complications.
One group of experts, who trawled through evidence, admitted the data is mostly based on assumptions and called for further trials to clarify the danger.
One major study, published in the New England Journal of Medicine, warned that smokers are at higher risk of severe COVID-19.
Researchers supported by the National Health Commission of China looked at more than 1,000 patients diagnosed with the coronavirus.
The scientists found, of the 913 patients with symptoms classed as non-severe, only 11.8 per cent, were current smokers.
However, 16.9 per cent of the 172 COVID-19 patients with severe symptoms were smokers, according to the analysis.
Furthermore, 25.5 per cent of the patients who needed mechanical ventilation, were admitted to intensive care or died were smokers.
The study also claimed asthma and chronic obstructive pulmonary disorder (COPD) are not risk factors for catching the infection - contrary to the National Health Service (NHS) advice.
Results also showed that hypertension was the most common comorbidity, with 30 per cent of patients having high blood pressure.
Respiratory doctors at The Central Hospital of Wuhan carried out another study that found smokers were more likely to see their disease progress.
They analyzed 78 patients who already had pneumonia caused by COVID-19. All of them were tracked for two weeks.
The experts, led by Wei Liu, found those who use tobacco are 14 times as likely to have COVID-19 progression.
Patients who had high levels of C-reactive protein - a tell-tale sign of inflammation - were 10 times more likely to see their disease progress.
Another study, published in the New England Journal of Medicine, came to a similar conclusion.
Researchers supported by the National Health Commission of China looked at more than 1,000 patients diagnosed with COVID-19. They found of the patients with symptoms classed as non-severe, only 11.8 per cent were current smokers.
However, 16.9 per cent of COVID-19 patients with severe symptoms were smokers, according to the analysis.
The WHO said people with pre-existing medical conditions (such as asthma, diabetes, heart disease) appear to be more vulnerable to becoming severely ill with the virus.
WHO advises people of all ages to take steps to protect themselves from the virus, for example by following good hand hygiene and good respiratory hygiene. (DailyMail)