EXPERT REACTION: Adelaide baggage handlers COVID-19 cluster

Technically, it could be possible that the baggage handlers picked up SARS-CoV-2 from luggage, but it's much more likely (given what we know about the main transmission routes of this virus) that they have picked up SARS-CoV-2 from a traveller at the airport. This could have either been through large droplets directly exhaled from an infected person, contact with fomites, or contact with infected faeces, for example if using bathrooms shared with the public (SARS-C-V-2 can be found in faeces).

A recent study published in NEJM on March 17 showed that the survival of the virus on plastic and steel in the laboratory was up to 72 hours (three days). In the real world, the humidity and temperature (and the fact that the virus is in mucus rather than buffer made in the lab) may change the survival characteristics, and we don’t fully understand this yet.

Plastic and other hard surfaces are common luggage materials, so we can make an assumption that the virus would survive quite well on these surfaces. If the luggage is made of a more porous material like cloth, I think the virus wouldn’t survive as well.

If travellers want to clean the outside of their luggage, they can wipe it down with hot water and detergent and then wash their hands really well afterwards (at least 20 seconds, lots of soap and water). A diluted (0.1 per cent) bleach solution may be possible but that would really depend on the type of surface, as bleach is very corrosive.

• How long can the virus survive on a hard surface such as a suitcase?

“I think we are still learning and asking questions about the exact mechanism involved here.

Most transmission seems to involve ‘close contact’ of people, but there may be less common cases involving different routes. This includes indirect fomite spread (for instance touching baggage which had virus deposited on it elsewhere days earlier). Transmission from long range aerosols and even the oral fecal route in theory are possible, but there are no examples that I am aware of yet.

There are really only a few papers I am aware of which have examined COVID-19 on surfaces. All these studies should be regarded as indicative only, and reflect what we can do in a lab.

One study found the virus was very stable at low temperatures, 4°C, but not at 70°C for five mins.  In the lab at 22°C it was stable for fewer than three hours on paper, fewer than two days on wood and cloth, fewer than four days on glass and banknotes, fewer than seven days on stainless steel and plastics, and was still active on the outer surface of masks at seven days.

An earlier paper found 1,000-fold reductions in virus titre in 72 hours on plastic, 48 hours on stainless steel, 24 hours on cardboard, suggesting a half-life of around six to eight hours on plastic and stainless steel. The same study found that aerosols which were artificially suspended were viable after three hours.

There was recently a case of virus being found on a cruise ship after 17 days. However, this involved traces of the genetic fingerprint of the virus, not virus which could infect cells or a person, so 17 days survival is likely an overestimate.

It is important to note that the studies are conducted in the laboratory, the virus is in buffers and not mucus (mucus may stabilise it), and the conditions are standardised.

Not all plastics may be the same, but these studies are a good pointer to try to understand what is happening in the real world.  I don’t know if one baggage handler became infected elsewhere by close contact spread, and similarly spread it to colleagues, all chatting in the tea room, or if they touched contaminated baggage.

To me at present all are possible and it is important that we find out as much as we can as soon as we can.”

• What can travellers do if they are concerned their luggage could have been exposed?

“If you have reason to think luggage has been exposed, it could be wiped down with an alcohol sanitiser (check that was safe to use on the material), or warm soapy water. Until we know more about the mechanisms of transmission, routes like baggage and mail are better thought of as possible in theory but unlikely, and in most cases transmission involves close contact between people. So keep your social distance at all times, wash your hands frequently, and make sure that anyone with any symptoms of COVID-19 is fully isolated until checked.”

I arrived on an international charter flight this morning from Poland. At the airport we were met with several staff who were involved in either ushering travellers for mandatory quarantine, COVID-19 screening or border control. 

I can’t speak for how the luggage handlers are being protected, but I can certainly comment on infection control and prevention of the staff deployed at the airport last night.

Face masks and gloves were worn, however on several occasions the staff member (and the same behaviour was amongst the general public) would pull off their face mask with their gloved hands to speak to us.

If the person had touched a metal or plastic surfaces where the virus can remain viable for two or three days, respectively, then it would have transferred to the face mask, which could transfer onto the person's face if the mask is constantly being handled.

If luggage handlers are instructed to load and unload contaminated bags with gloved hands and these gloves are either not used properly or not regularly changed then the risk to exposure is likely.

If luggage handlers or the general public more broadly are using contaminated gloved hands to make phone calls or text on their mobile, this is another potential source of contamination.

Are surgical gloves providing a false sense of protection amongst people who are not trained in regular glove use?

Healthcare staff know that  when gloves are worn they are replaced between each patient and hands are washed. Improper use of PPE (personal protective equipment - i.e. gloves and face masks) is dangerous and counterproductive.

Fomites are objects or material that can carry pathogens. In this case, it is quite possible that the luggage is acting as a fomite, and the baggage handlers have picked up the virus from the bags they manoeuvre. Estimates of how long the Coronavirus stays on surfaces ranges from two to ten days. They should be wearing gloves while working, and preferably a simple surgical face mask. The face mask is not to prevent them breathing in viral particles, but rather to stop them from touching their faces. 

Clearly, passengers are at risk for the same reason. However, passengers can avoid infections by regularly using hand sanitiser on their journey, and rubbing some on to luggage handles before they pick them up.

• Are the baggage handlers likely to have caught the virus from handling luggage, or from contact with people in the airport?

"Transmission of the virus is possible either through direct contact with a person or by touching a contaminated surface.

Our current understanding would suggest that one would be much more likely to have become infected by person-to-person transmission than by touching a contaminated surface.

To get COVID-19 by touching a contaminated surface the following would have to happen: there would need to be virus deposited on the luggage by an infected person, the virus would have to still be viable, the baggage handler would need to get it on their hands, then the baggage handler would need to have touched their face.

However, it is just impossible to know how transmission occurred without further information about the movements and activities of the baggage handlers, and then even then the exact mode of transmission may still not be clear."

• How long can the virus survive on a hard surface such as a suitcase?

"The current evidence seems to suggest that the virus may survive up to three days on hard surfaces such as stainless steel and plastic. It is also appears that it may survive on cardboard for up to four hours and somewhere from a few hours to a day on clothes or fabric. How long it survives on surfaces depends on the environmental conditions, specifically the temperature and humidity. Warm temperatures and a lack of moisture will dry out the virus and inactivate it.

Its important to note that the amount of viral particles decreases fairly rapidly over time on these surfaces, so your risk of infection would also decrease over time. The greater the dose of virus you are exposed to the greater the likelihood of being infected."

• What can travellers do if they are concerned their luggage could have been exposed?

"In this current environment, it would make sense if someone believed that others have handled their luggage and could possibly have contaminated it, then wiping luggage down would seem like a sensible precaution.

However, the key preventative action is to wash hands regularly so that virus that you have come into contact with from any surface is washed off your hands so that if you touch your face you do not get infected."

• Are the baggage handlers likely to have caught the virus from handling luggage, or from contact with people in the airport?

"The most likely scenario is that they caught it from other staff, or from touching surfaces contaminated by passengers or other staff. While the virus has been shown to survive on surfaces for several hours and even days under optimal conditions the likelihood they got it from the bags is minimal, particularly as generally they wear gloves when handling luggage.

• How long can the virus survive on a hard surface such as a suitcase?

"Theoretically, the virus could survive for several hours on a luggage handle. However, that would require someone infected who has contaminated their hands to have directly handled the suitcase handle to contaminate it. This is highly unlikely."

• What can travellers do if they are concerned their luggage could have been exposed?

"Wipe the luggage handle with an alcohol wipe before handling with bare hands."

It is possible that this coronavirus cluster arose from contaminated baggage. But it is also possible the virus was spread amongst the baggage handlers by an already-infected co-worker.

It would be extremely difficult to pinpoint the source of this particular cluster of infection.

Does this mean coming into contact with baggage could spread infection? Yes that is possible under certain circumstances.

All the more reason why we must all be especially vigilant at these times and to the greatest extent as possible reduce contact with others and avoid travel.

Viruses have been found to survive on plastic and other hard surfaces from hours to days, depending on the virus. The strongest viruses are usually ones that infect your gut and give you gastro symptoms. The structure of these viruses help them survive longer without someone to infect.

Recent findings from the National Institute of Allergies in the US have shown that the COVID-19 can survive for about three days on plastic surfaces. The survival of viruses on surfaces depends greatly on the ambient temperature and humidity. If air is drier and hotter than normal, then viruses have a harder time surviving.

For those concerned about hard surfaces at home (durable plastics, stainless steel, stone), current recommendations for disinfection is to use a 0.1 per cent bleach solution and let the solution remain on the surface for 10 minutes before wiping with a disposable cloth or paper towel. However, this can damage certain surfaces.

Hydrogen peroxide and 70 per cent ethyl alcohol-based products are also effective, when used correctly. It is important to use a properly labelled and approved disinfectant (by the TGA or United States EPA) and to follow the manufacturer’s recommendations for use. It is also important to use products that are disinfectants rather than cleaners. Cleaning means removing dirt and grime, but disinfection means destroying microorganisms.

For those concerned about being in contact with the virus, it’s important to follow the current recommendations for hand washing and self-isolation. If you experience symptoms which you think are related to a potential exposure, you should ring your GP or the National Coronavirus Helpline on 1800 020 080 first for guidance.