How do facemasks, distancing reduce the risk of contracting coronavirus?

Following Covid-appropriate behaviour, using non-medical interventions such as wearing a face mask, face cover and maintaining a minimum of six-feet distance, can significantly reduce the risk of transmission of the coronavirus from an infected person, a graphic shared by the Indian Union ministry of health and family welfare on Tuesday showed.

Taking to Twitter, the ministry tweeted the graphic with the text "Follow Covid appropriate behaviour to lower the risk of transmission." The image showed the varying levels of risk of an uninfected person contracting the virus from those already infected, with the highest chance of transmission being 90% risk when no distance is maintained and no face masks or covers are used.

However, the chance of transmission remains the lowest with negligible risk when a facemask and cover is worn and a minimum of six-feet distance is maintained from the patient, the image showed.

The graphic also highlighted that discarding the distancing rule, despite both the infected and the uninfected wearing a face mask and cover, posed a 1.5% risk with a low chance of transmission of the virus. Also, when the uninfected person is without a mask and within six feet of an infected person, the risk increases to 5% with a medium chance of transmission, even if the infected person is masked, the graphic showed.

In the advisory, the health ministry red-flagged two conditions which posed a bigger risk with higher chances of transmission. When an infected person is not wearing a mask, the risk increases to 30% with a high chance of transmission within six-feet distance, in spite of the other person wearing a mask.

The highest chance of transmission is possible when all such safety measures are discarded and both the infected and uninfected do not wear a mask or a face cover and are within six feet distance of each other. The risk increases to 90% in this case, the image showed.

The advisory from the ministry comes at a time when the country is reeling under the second wave of the pandemic. Daily new cases in India remained upwards of the 300,000-mark for the fifth straight day, earlier on Monday, according to official data.