Covid-19 coronavirus: Height factor points to transmission through the air

Healthcare workers test patients in their cars at a coronavirus testing site in Las Vegas. Photo / AP

People taller than 1.82m have more than double the chance of testing positive with Covid-19, a new survey suggests.

An international team of researchers, including experts from the University of Manchester and the Open University, surveyed 2000 people in Britain and the United States, looking at whether personal attributes, work and living practices might influence transmission of the virus.

The team found that taller people were at higher risk, which the scientists said suggested that the virus was transmitting through the air, as height would not make a difference if people were contracting the diseases exclusively via droplets.

Aerosols can accumulate in poorly ventilated areas and are carried by air currents.

Droplets, however, are bigger than aerosols and are thought to travel relatively short distances and drop quickly from the air.

WHAT ARE THE CHANCES?
- 1.82m or taller - 2.2x increase
- Extrovert - 50 per cent increase
- Working with reduced earnings - 2.9x increase
- University degree - 55 per cent decrease
- Shared kitchen - 2.2x increase
- Redundant or unemployed - 5.6x increase

The results suggest downward droplet transmission is not the only transmission mechanism and aerosol transmission is possible.

Professor Evan Kontopantelis, from the University of Manchester, said: "We expected taller men to be more protected when in reality they were not.

"The findings indicate that aerosol transmission is extremely likely and not only that, taller men have a higher risk in the UK, possibly because of their behaviour - 'I am tall and it has crossed my mind that I would be protected if I keep my head high if others sneeze beneath me' - but it seems these particles go up in the air and linger there for a long time, so everyone needs to protect themselves."

The study showed that the baseline risk for anyone testing positive for coronavirus in the study was between five and 10 per cent.

But being more than 6ft tall (1.82m) doubled the risk.

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The survey found that using a shared kitchen or accommodation - a proxy for deprivation - was also a significant factor in both the US and UK but especially in the US, where the odds were 3.5 times as high. In Britain, they were 1.7 times higher.

And the study also found that people with natural science degrees in the UK were slightly less likely to contract the disease.

Although the paper is yet to be peer reviewed, the authors say that it might help people take greater precautions and help to refine shielding guidance.

Professor Paul Anand, a research director at the Open University, said: "Much scientific research has focused on patterns of spread and underlying mechanisms of transmission. But as economies and societies reopen it is important to know more about the role of personal factors as predictors of transmission.

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"Though both are market economies, the US and UK differ in the extent and manner in which they provide access to healthcare and welfare support - and that to some extent is demonstrated by the associations shown by the data."

Rolando Gonzales Martinez, researcher of the University of Agder in Norway, said: "Both structural and individual factors must be taken into account when predicting transmission or designing effective public health measures and messages to prevent or contain transmission."

He added: "But it would be helpful to have repeat observations so more could be said about changes over time."