Coronavirus: Putting hamsters on plane could test transmission

Placing hamsters on an aeroplane could be one way of examining whether coronavirus can be spread through airborne transmission, an infectious disease specialist has suggested.

Epidemiologist Professor David Heymann said further ‘complex studies’ were needed to see if people could catch Covid-19 through air circulating on planes or through restaurant air conditioning systems.

He said scientists could use animal studies to test for the potential spread of the illness, an approach previously used for tuberculosis research.

Speaking at a Chatham House briefing on Wednesday, Prof Heymann argued that ‘epidemiological indicators’ in some countries where people could move about in public did not point to an ‘increased transmission’ that may occur if the virus was airborne.

Pictured: File photo of a European Hamster crawling from its burrow. A top epidemiologist said today that the virus's airborne transmission potential could be researched using live animal subjects

Pictured: File photo of a European Hamster crawling from its burrow. A top epidemiologist said today that the virus’s airborne transmission potential could be researched using live animal subjects 

A top epidemiologist today said that airborne transmission could be determined using animal test subjects on planes to see whether they became infected through the vehicle's air circulation system. Pictured, people wearing face masks in Thailand, July 8

A top epidemiologist today said that airborne transmission could be determined using animal test subjects on planes to see whether they became infected through the vehicle’s air circulation system. Pictured, people wearing face masks in Thailand, July 8

Professor David L Heymann (pictured) speaks during a WHO press conference in July 2016

Professor David L Heymann (pictured) speaks during a WHO press conference in July 2016  

His comments come after the World Health Organisation (WHO) acknowledged there is ’emerging evidence’ that Covid-19 could be spread through particles in the air.

More than 200 scientists wrote an open letter to the agency urging officials to recognise the possibility of airborne transmission of the virus.

Current guidelines from the WHO focus on the virus being spread primarily through droplets from the nose or mouth, which are expelled when an infected person coughs, sneezes or speaks.

The Geneva-based agency advises precautions to avoid these droplets, such as social distancing and regular hand washing.

But signatories of the letter, published in the Clinical Infectious Diseases journal, have called on health officials to update guidance to include measures which would mitigate the risk of airborne transmission, such as providing sufficient ventilation, to minimise recirculating air, and avoiding overcrowding – particularly on public transport.

Prof Heymann said on Wednesday: ‘What we believe is that there is a possibility that there is this airborne transmission in enclosed spaces, that an air conditioning unit, especially one on the wall, might be able to pick up an aerosol, and then spit it back out, if it’s not filtered, into the room and circulated throughout the room.’

He explained coughing or sneezing can transmit the virus through spreading droplets either directly or if they are propelled as aerosols over a distance of around a metre.

Another type of aerosolised transmission – airborne – could be where droplet particles are moved by other means such as air conditioning units.

But he emphasised that the WHO was waiting to examine the results of ongoing studies in this area.

Facemasks designed to stop the spread by droplets, as was previously instructed by the WHO. Pictured, people wearing face masks while queueing outside Ikea in Dublin, Ireland, June 8

Facemasks designed to stop the spread by droplets, as was previously instructed by the WHO. Pictured, people wearing face masks while queueing outside Ikea in Dublin, Ireland, June 8

‘One of these is to put an animal that can be infected with this virus into various places around rooms in hospitals or wherever, to see if those animals are being infected, and that’s being done with hamsters,’ he said.

‘In the past it was done for tuberculosis with guinea pigs, the hamsters can be infected with this virus, and there are actually cages sitting around in their various parts and experiments that are being done by academic institutions that will give us information as to whether or not this virus is spreading in aerosols, in airborne transmission.’

Asked if there was any evidence of airborne transmission occurring beyond theoretical studies, Prof Heymann said there was ‘some anecdotal evidence’ of physically distanced people becoming infected in a restaurant in China.

‘And one of the hypotheses is that this was the air conditioning unit,’ he said.

But citing examples of countries with low reproduction rates of the virus, such as Switzerland, Prof Heymann said: ‘There’s not been any indication that this is just airborne and spreading in the community so that if you walk down the street you could be infected.’

He warned that if the virus was airborne, people’s eyes would be ‘even more at risk of being an entry point for the virus’.

But Prof Heymann, who works at the London School of Hygiene & Tropical Medicine, said people should not think that wearing a face mask would protect them outdoors from any type of infection, which could only be done through full personal protective equipment (PPE).

‘The message is protecting yourself involves physical distancing. It involves hand washing, and it involves, when you can’t physical distance, wearing a mask to protect others,’ he said.

He also argued: ‘If there is airborne transmission we need to better understand it before we can put interventions in place.’

Prof Heymann added: ‘What we don’t know yet, is whether this virus can get into air systems on an airplane or into air systems, in an air conditioning system in a restaurant for example, but there’s no evidences yet that shows that it does.

‘And so, collecting that evidence over time, maybe doing experiments, maybe putting guinea pigs, or hamsters rather, on airplanes and flying them around with airborne transmission might be a way of showing those things, but these are complex studies which need to be developed in order to understand, and this is observation.’

He continued: ‘Observation will tell us now that airlines are flying again whether or not people are getting infected on airplanes, and it will tell us whether or not people are getting infected in spaced restaurants, in areas like that.’

He said SARS (severe acute respiratory syndrome) coronavirus did not transmit through circulating air, albeit had a different means of reproduction in the lungs, while tuberculosis does not transmit on aeroplanes.

Prof Heymann said that, in the absence of evidence of airborne transmission, individuals should choose to fly based on their own perception of risk and follow airline guidelines.

Prof Keith Neal, emeritus professor of the epidemiology of infectious diseases at the University of Nottingham, said separately on Wednesday: ‘Aerosol transmission cannot be ruled out but we need to know which routes – droplets, aerosols or surface contamination – are important as an infection risk.

‘Until we do, social distancing, cough etiquette and hand washing remain important.

‘We may move to more face coverings indoors but the evidence isn’t there yet.’ 

IS THERE ANY EVIDENCE SARS-COV-2 DROPLETS LINGER IN THE AIR? 

Airborne diseases are those where germs from a person’s breathe, sneeze or cough can linger in the air and travel because the droplets are very small in size.  

Aerosols are so small and can linger in the air for longer and travel further. They include tiny particles like smoke, which can stay airborne for up to eight hours.

There is some compelling evidence to say that SARS-CoV-2 is airborne, despite most of it not being subject to peer review. 

The virus can remain in the air ‘for three hours’

Scientists in the US have shown in the laboratory that the virus can survive in an aerosol and remain infectious for at least three hours.

However, at the time the WHO argued the conditions of the experiment were too artificial and did not represent what happens if someone coughs in real life. 

The virus spread between diners at a restaurant who had no contact 

One study revealed how a cluster of people caught the coronavirus in a restaurant without being in contact with each other.  

Nine people in three families in Guangzhou, China, were diagnosed with the virus after eating at the same restaurant as the ‘source’ patient. But the researchers said droplets from coughing and sneezing alone could not explain the spread of the virus. 

The team, led by Yuguo Li at The University of Hong Kong, measured the ventilation in the room and concluded that ‘aerosol transmission of SARS-CoV-2 due to poor ventilation may explain the community spread of COVID-19’.  

However, the same cluster of cases was studied by a different group who reported their own conclusions in a Centers for Disease Control and Prevention (CDC) journal on April 2.

Jianyun Lu and colleagues from the Guangzhou Center for Disease Control and Prevention said: ‘From our examination of the potential routes of transmission, we concluded that the most likely cause of this outbreak was droplet transmission. However, strong airflow from the air conditioner could have propagated droplets.’ 

The team admitted droplets from coughing and sneezing alone could not explain the spread of the virus. 

The virus can linger in crowded places 

In April, Chinese researchers found that the coronavirus can linger in the air of crowded places and published their findings in the journal Nature.

Experts in Wuhan, the Chinese city where the pandemic began, analyzed air samples from 30 sites across the city – in which coronavirus was first reported – including inside hospitals as well as public areas.

Results showed the virus, called SARS-CoV-2, was too low to be detected in all areas except two ‘prone to crowding’.

Viral particles were found floating in the air of hospital toilets, which had very little ventilation. 

They also discovered especially high concentrations in the rooms where medical staff put on and took off protective gear.

The latter suggests the virus can latch onto clothing and become airborne again when when masks, gloves and gowns are removed.

Researchers behind the study say the findings highlight the importance of ventilation, limiting crowds and proper disinfection.

source: dailymail.co.uk