WHO rethinking how coronavirus spreads in air

There is an emerging but not yet definitive evidence from a group of experts that coronavirus can be airborne.

The World Health Organisation (WHO) is in the process of reviewing evidence by experts that seem to indicate that the virus that causes Covid-19 is airborne in certain settings.

Although the health body says the evidence is not definitive, they indicated that there is a possibility of airborne transmission of the virus in specific conditions that are crowded, closed or poorly-ventilated.

WHO acknowledged they have been in discussions with the various signatories of the research pieces since April 1 to get their contributions towards the growing body of knowledge on the pandemic.

From their engagement with many of the signatories who are engineers, WHO consider this a wonderful area of expertise, which adds to the growing knowledge about the importance of ventilation.

“We have been talking about the possibility of airborne and aerosol transmission as one of the modes of transmission of Covid-19 as well as droplets, fomites, faecal-oral, mother-to-child transmission and animal to human transmission as well,” Dr Maria van Kerhkove, WHO technical lead for Covid-19, said.

From the various research data that WHO receives, a consolidated scientific brief on Covid-19 transmission will be produced by groups of epidemiologists, clinicians, infection prevention and control experts, engineers and mathematics modellers in the coming days.

Emerging evidence

Prof Benedetta Allegranzi, WHO specialist in Infection Prevention and Control, acknowledged that there is emerging evidence in the field of coronavirus transmission like in other fields of the virus.

“We believe that we have to be open to this evidence and understand its implications and the precautions which need to be taken,” Prof Allegranzi noted.

The WHO experts reiterated that the coronavirus is a respiratory pathogen thus a comprehensive package of interventions are required to be able to stop its transmission.

“We welcome interactions from all scientists across the world from many different disciplines,” Dr Maria said.

According to Allegranzi, it will be important to know the different sizes and dose of virus needed in the aerosol or airborne transmission of the virus.

According to WHO’s chief scientist, Dr Soumya Swaminathan, guidelines that are developed are based on a well-established process but in an emergency situation such as the current pandemic, where the organisation gets thousands of new data every day, this evidence is reviewed daily but still has to go through peer review.

Scientists believe that with the number of “research evidence” being presented to WHO, the health body has to balance between what is known about the evolution of the virus and human behaviour to get be able to quantify the risk of aerosols in the air. 

“You can find different sizes of droplets in the air, but the smallest aerosols can last for a bit,” Prof Matilu Mwau, a Deputy Director at Kemri sad.