An analysis of an Associate Professor of Biology at the University of Massachusetts Dartmouth has revealed that the COVID-19 infection can spread within 5 minutes to 50 minutes.
Professor Erin S. Bromage’s analysis of spreading of the Coronavirus infection stated that just more than 10 minutes of exposure to an infected person in a face to face situation can potentially get anyone infected and sharing a space with an infected person, for example, office, for a longer period will get such person or people potentially infected.
Sneezes and coughs of such infected people can infect a whole room of people. That is why, he says, it becomes mandatory for symptomatic people to stay home.
Erin gave an insight into how fast can a person get infected from the virus. In his analysis Erin talks about a formula – Successful Infection = Exposure to Virus x Time
It means that a successful infection depends upon the exposure to a number of virus particles for a particular period of time.
Based on various infectious diseases’ studies, Erin said that some experts estimate that as few as 1000 SARS-CoV2 infectious viral particles are needed to get someone infected.
He agreed that this still needs to be determined experimentally. However, he used the number to demonstrate how infection can occur.
“Infection could occur, through 1000 infectious viral particles you receive in one breath or from one eye-rub, or 100 viral particles inhaled with each breath over 10 breaths, or 10 viral particles with 100 breaths. Each of these situations can lead to an infection,” said Erin.
To understand this, Erin segregated different acts on the basis of virus particles released by different acts and which is the environment that is most conducive for this infection.
Coughing and sneezing:- As per Erin’s analysis, a single cough releases about 3,000 droplets. Most of these droplets drop on the ground quickly but many stay in the air. Droplets through cough travel at 50 miles per hour which means the airborne droplets can travel across the room in few seconds. He further analysed that a single sneeze releases about 30,000 droplets, most of them small and can travel easily across a room at 200 miles per hour.
Erin concludes that droplets in a single cough or sneeze of an infected person may contain as many as 20,00,00,000 virus particles which can all be dispersed in the environment around them.
So, during a face-to-face conversation with an infected person, if he sneezes or coughs it is quite possible to inhale 1000 virus particles easily and get infected.
Even in case of indirect cough or sneeze, the smallest of infectious droplets can fill the room and a person coming into the room within few minutes of such sneeze or cough can potentially receive enough virus through a few breaths to get infected.
Breathing: Erin observed that one breath can release 50-5000 droplets. Citing a few studies he said that influenza can release up to 33 infectious viral particles per minute. But for SARS-CoV2 Erin kept the number at 20.
He said that if every viral particle is inhaled (unlikely), it will take 50 minutes to get one infected.
Erin further observed that speaking increases the release of respiratory droplets about 10 fold which means 200 virus particles per minute. So, while talking face to face if every viral particle is inhaled, 5 minutes of such conversation can be a sufficient dose for infection.