Dar es Salaam. Over 200 scientists have written an open letter to the World Health Organization (WHO) pushing it to recognize evidence that the disease can be airborne.
The scientists say that Covid-19 can be transmitted through breathing out, talking and coughing and poked holes in WHO’s assertion that aerosolised transmission is limited to hospital settings.
WHO says it is reconsidering emerging evidence indicating that Covid-19 can be transmitted through the air.
According to the WHO, this form of transmission is limited to aerosol generating procedures such as endotracheal intubation, bronchoscopy, open suctioning, administration of nebulised treatment.
Others are manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, non-invasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation.
The agency agrees with two forms of transmission of Covid-19 – through saliva droplets from an infected person and touching of contaminated surfaces. But the scientists argue the virus can also be transmitted through the air. In the letter published on Monday by the Journal Clinical Infectious Disease (Oxford Academic), the scientists said it is time to address airborne transmission of Covid-19.
“There is a significant potential for inhalation exposure to viruses in microscopic respiratory droplets at short to medium distances (up to several metres, or room scale),” they wrote.
They argued that studies they carried out “demonstrated beyond any reasonable doubt that viruses are released during exhalation, talking and coughing in micro-droplets small enough to remain aloft in the air and pose a risk of exposure at distances beyond two metres.
The experts explained that retrospective studies conducted after the Sars-CoV-1 epidemic showed that airborne transmission was “the most likely mechanism explaining the spatial pattern of infections”.
They therefore undertook retrospective study on Sars-CoV-2, the virus that causes Covid-19, and established the same pattern.
The experts cited a Chinese restaurant where people got infected despite having no direct or indirect contact between them.
Another study on the same issue published on Tuesday in the Journal Emerging Infectious Diseases of the Centres for Disease Control and Prevention (CDC), experts argued that the most probable route of the virus transmission was droplet diffusion “prompted by air-conditioned ventilation.”
The Oxford researchers, led by Lidia Morawska and Donald K. Milton, also based their argument on studies done on the spread of other viruses including respiratory syncytial virus (RSV), the Middle East Respiratory Syndrome coronavirus (Mers-CoV) and influenza, which show that “viable airborne viruses can be exhaled and or detected in the indoor environment of infected patients.”