WHO Director-General's remarks at the launch of the through-the-air-transmission report – 18 April 2024

Chair, Professor Kang,

Co-Chair Professor Li,

Dear colleagues and friends,

Thank you all for joining us today, and greetings from Washington DC.

I thank our chairs and all the members of the technical working group for lending their time and expertise to this significant report.

I also thank the four centres for disease control and prevention - from Africa, China, Europe, and the United States - for their commitment and partnership in this endeavour.

In the early days of the COVID-19 pandemic, it became clear that different scientific disciplines used different terms to describe the transmission of pathogens through the air.

These differences had the potential to cause confusion about how COVID-19 was transmitted, and who was at risk.

Like the debates over vaccines, masks and lockdowns, there was a strong debate over how to describe transmission of COVID-19.

Unfortunately, that debate was sometimes polarised, negative, over-simplistic, and hampered constructive scientific discussion.

As I've said previously, it's not who is right, but what is right.

A constructive discussion was needed, because while the science of transmission through the air had advanced significantly, the terminology had not.

This discussion is relevant not only for COVID-19, but for other respiratory diseases including tuberculosis, influenza, measles, SARS and others.

While the new terminology included in this report are being published by WHO and partners now, WHO has provided advise to reduce all transmission types.

To bring the terminology in line with updated science, two years ago WHO established a Technical Consultation Group of 41 experts from all regions of the world.

They represent a wide range of disciplines including epidemiology, microbiology, clinical management, infection prevention and control, bioengineering, physics, air pollution, aerosol science, aerobiology, public health and social science, as well as disease experts.

As per normal WHO practice, all members of the group were screened for conflicts of interest, and no relevant conflicts were identified.

The expert group met multiple times, both in person and virtually.

WHO consulted extensively within these and other fields, and received more than 500 separate inputs, which were all considered.

Incorporating these diverse perspectives was crucial, as we worked to reach consensus on common language across scientific disciplines.

The discussions were complex and challenging, and demonstrated the diversity of views and uses of terminology. This was far from a simple issue.

But with persistence, patience, robust debate and goodwill, the advisory group was able to reach agreement.

It's also highly significant that the four CDCs have endorsed this report.

This is a major step. For the first time, we have globally agreed-upon terminology for how pathogens transmit through the air.

In addition, WHO and CERN have developed a robust risk assessment tool for indoor airborne transmission.

This tool is aimed at improving our understanding of COVID-19 airborne transmission risk in indoor space in order to design and utilise mitigation measures to reduce this risk.

But this is not the end of the process - it's just the end of the first stage.

This revised terminology must now be used by WHO and other public health agencies across different pathogens and in different settings.

Once again, I offer my deep gratitude to the chairs and members of the Technical Consultation Group and the four CDCs for their collaboration and partnership in this vitally important project.

It's a project that demonstrates the essence of WHO's work: bringing together leading experts from across disciplines and geographies, to study the evidence and provide a common approach that everyone can use.

I also thank my colleagues in the WHO Secretariat for their hard work in facilitating this process over such a long period of time.

In the end, this process is not about semantics - it's about giving scientists and public health experts the tools they need to do their jobs, and save lives.

I thank you.

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