NEW DELHI : Loss of smell may be the best predictor of Covid-19 among patients with symptoms of respiratory diseases, according to new research.The findings of two new international studies, published in the journal Chemical Senses, show that there is frequent loss of smell in Covid-19 patients which often lasts for a long time.Over 4,500 Covid-19 patients from a total of 23 nationalities responded to the researchers' questionnaire.Also Read | Why server stacks are the new realty playThe studies found that the average loss of the sense of smell was 79.7 on a scale from 0-100, indicating a large to complete sensory loss."This emphasises how important it is to be aware of this symptom, as it may be the only symptom of the disease," said.