New research conducted by Professor Michael Ward, an epidemiologist in the Sydney School of Veterinary Science at the
University of Sydney, and two researchers from the Fudan University School of Public Health in Shanghai showed that
humidity is an important factor in the transmission of covid-19.
In this first peer-reviewed study of a relationship between climate and covid-19 in the southern hemisphere, researchers
found a link between lower humidity and an increase in locally acquired, positive covid-19 cases.
This indicated the likes of Australia and New Zealand could face a heightened risk of the disease throughout winter,
pharmaceutical scientist Sir Ray Avery says.
Researchers discovered a one percent decrease in humidity could increase the number of covid cases by six percent.
“We have a lot of armchair New Zealand epidemiologists who have advised the government using theoretical statistical
modelling on how to prevent the spread of covid -19 but this is a rare forensic epidemiology study that provides a true
insight into the spread of covid,” he says.
“For more than 30 years my team has been designing hospital high efficiency particulate Air filtration systems in
intensive care units in hospitals in Africa and Asia.
“We quickly learnt that influenza and common respiratory virus have similar environmental survival, but different routes
of transmission survived longer in air and on surfaces and may be transmitted further in dry cold conditions.
In contrast, warm humid climates discouraged aerosol transmission of influenza, by reducing the amount of influenza
virus aerosolised and reducing influenza survival rates.
“The pandemic in China, Europe and North America happened in winter and there is definitely a link between temperature
and humidity and population densities as key determinants in the spread of covid.
“Our government’s lockdown modelling data was based on a set of environmental and demographic conditions prevalent in
the northern hemisphere and irrelevant in the New Zealand and Australian summer settings. Covid just doesn’t like warm
humid environments so transmission rates are low.
“However what we can learn from this latest research and our own occupational health setting data is the infection rate
of covid will increase as we move into our low humidity winter and indoor social distancing will be meaningless as
viruses can travel as far as 20 metres in closed room environments with low temperatures and low humidity.”