Although new COVID-19 variants are continuing to emerge around the world, scientists and doctors have already started preparing for the next pandemic to arrive.
And as experts learn more about how climate change can affect the mutation and spread of infectious diseases, it might not be a question of if another will emerge – but when.
“After the end of the recent coronavirus pandemic, the whole world is actually preparing for the next pandemic,” said Zhang Wenhong, director of China’s National Medical Centre for Infectious Diseases.
In 2020, Zhang was appointed leader of Shanghai’s clinical expert team for COVID-19, becoming a household name and central figure in the country’s fight against the virus.
He has published hundreds of papers in the field of public health and infectious diseases. But now he is embarking on a new initiative to address the intersection between two growing threats: climate change and infectious diseases.
While the world is often more concerned by the observable impacts of climate change such as extreme, catastrophic weather events, Zhang said a growing body of research was now examining the indirect impact of a warming climate on the mutation and spread of pathogens.
Research examining this relationship “will become a growing focus globally”, he said.
As the planet’s climate changes, including the expansion of the tropics, the way pathogens evolve and mutate is also changing.
A study published in the peer-reviewed Journal of Geophysical Research: Atmospheres in 2020 found that ocean surface warming in subtropical regions was expanding the width of the tropics.
“The reservoir of bacteria and viruses is expanding as the Earth warms,” Zhang said, adding that this will expose more animals to bacterial, viral and fungal infections as pathogens and their vectors like ticks and mosquitoes obtain more habitable land.
In the United States, the incidence rate of encephalitis and Lyme disease, both spread by ticks, is growing. Meanwhile in China, mosquito-borne dengue fever is increasingly being found in areas where it has not thrived before.
“It has been expanding from near the south – the more tropical areas – towards the north, and now it has also begun to expand to the Yangtze River Basin. So we can now also detect dengue fever in the Yangtze River Basin,” Zhang said.
Across Southeast Asian and African countries “not only has malaria not been eliminated, but the number of cases are at very high levels”, and this was all related to climate change, Zhang said.
The World Health Organization (WHO) has said that in future decades climate change will affect the spread of vector-borne diseases like malaria due to changes in global temperature and precipitation patterns.
There is a hypothesis that the COVID-19 pandemic spread to humans from bats, whose habitats are also expanding.
Plus, as northern regions like Alaska continue to warm, “some species that have not emerged before may enter our human society”, Zhang said, including ancient species of bacteria and fungi.
“So the work we are doing now is actually for the next pandemic.”
But countries will need more data if they are to work together to create global disease management agreements and strategies to respond quickly to another global pathogen.
“(Scientists) mainly need to provide enough data, enough evidence, and provide corresponding suggestions” on how to build global pandemic preparedness, a goal that Zhang and others are now working towards.
As director of the Shanghai Sci-Tech Inno Centre, Zhang signed a memorandum of understanding with the University of Hong Kong (HKU) to work towards that goal at the annual Pujiang Innovation Forum in Hong Kong in late April.
As part of the project, experts in climate change, public health, infectious disease control and public policy will be brought together for research at HKU’s Centre on Contemporary China and the World (CCCW).
Resident and non-resident experts will “pursue original research, establish regular monitoring systems and provide public policy discourse platforms”, according to the CCCW.
“Using this platform, infectious disease experts and microbiologists can work with environmental experts and climate experts to conduct in-depth research on climate change and infectious diseases together,” Zhang said.
With more data and routine disease surveillance, he said, scientists might discover “alarms” for incoming pandemics that could serve as an early warning and trigger quick response actions.