I expect that, like most people, I am very concerned about the possibility of contracting the COVID-19 disease from the SARS-Cov-2 virus. The death rate for my age group (60-69) is about 3.6%1, and many people in that age group have underlying medical conditions which increases their risk. While I have cheated death a couple of times over my life, once as a baby with gastroenteritis, and once as an adult with septicaemia, I don’t want to push my luck, nor I imagine do many others. So, to try to minimise the risks, I thought it best to find out about how this virus is transmitted from person to person.
A recent study from Germany, which tried to work out when those who are infected can infect others, has helped explain the rapid and efficient way in which the virus has spread. They monitored the viral shedding of nine people infected with the virus. In addition to tests looking for fragments of the virus’s RNA (parts of its genome), they also tried to grow viruses from throat swabs, sputum, blood, urine and stool samples taken from the patients. This type of testing — trying to grow viruses — is critical in the quest to determine how people infect one another and how long an infected person poses a risk to others2,3.
The researchers found that they could not grow viruses from throat swabs or sputum from people after they had shown mild symptoms for 8 days. This is unusual, in that there are some people who have recovered from the illness, but are still testing positive for the virus. These tests are based on the use of Polymerase Chain Reaction (PCR) and may only be finding viral debris, rather than viable, infectious virus. Unfortunately, the researchers also found very high levels of virus emitted from the throats of patients from the earliest point in their illness, while they were still going about their normal lives. In people who had more serious illness, the viral shedding was more intense and lasted longer, up to 10 or 11 days after symptoms showed2,3.
When infected people sneeze or cough they shed coronavirus in droplets of sputum, and it was initially unknown how long the enclosed viruses remain infectious. A study done by the National Institute of Allergy and Infectious Diseases’ Laboratory of Virology in the Division of Intramural Research in Hamilton, Montana has apparently answered this question. The researchers used a nebuliser to blow coronaviruses into the air and found that the virus could remain infectious for up to three hours4. However, the droplets don’t tend to linger in the air for that amount of time; they usually fall onto a surface. If these droplets of sputum land on a copper surface, a recent study has found that the virus can remain infectious for up to four hours, up to 24 hours on cardboard and up to two to three days on plastic or steel4.
The virus enters the body through the mucus membranes of your face. These are the ‘wet’ parts of your face – the eyes, nose and mouth. The droplets containing the virus may go directly into your eyes, nose or mouth if someone coughs or sneezes nearby. Conversely, the droplets may have fallen onto a surface, or have been put onto a surface by an infected person coughing or sneezing into their hands and then touching the surface. You pick the virus up on your hands when you touch that surface. Then, if you rub your eye, scratch your nose, or lick your finger, you can ingest the virus. So, it is exceedingly important to avoid touching surfaces you do not need to touch. You can also catch the virus from an infected person directly by kissing, sharing eating utensils, drinking glasses, cups, straws or waterbottles5.
So, if you cannot stay at home and therefore out of the way of sputum projectiles, then avoid sharing utensils and tongue sandwiches. In addition, you should also wear a mask when out in public and, if possible wear safety goggles to prevent entry of the virus via the eyes. While many people seem to wear surgical masks, which are loose-fitting, these are not sufficient. The Department of Health and the Royal Australian College of General Practitioners recommend that, when collecting samples from infected people, medical staff should wear the tight-fitting P2 or N95 masks6. We have a couple of N95 masks left over from when the smoke from the black summer bushfires covered our city; we only used them for a few minutes when outside, preferring to seal ourselves inside the house until the smoke cleared.
Apart from masks and goggles, it is important to wash your hands with soap and water as often as possible, or use a hand sanitiser (containing alcohol). After every trip to the supermarket, pharmacy or doctor, when we hop back in the car, out comes the hand sanitiser and we give the hands a quick rubdown. The difficult thing before we get to the car is trying not to touch any surfaces, and not to touch your face. This is something I have caught myself doing without thinking; scratching my nose, rubbing my eye or fondling my earlobe. When we get home, the first thing we do is wash our hands. This is relatively easy for us, and hopefully it will be successful and we will avoid becoming infected. However, we have it easy, living alone in our bungalow with a fully stocked fridge and pantry, masks and not having to go out to work in essential services, supermarkets, pharmacies, surgeries, hospitals etc.. In addition, there are many people who are worse off than us. For instance, how would we cope if we were homeless, as over 116,000 Australians are7? How can we, in one of the wealthiest countries in the world condemn people to live on the street, in tents, or in temporary or emergency accommodation? As the infection rate in Australia skyrockets exponentially (now at 1715 cases8), how many of the homeless will be condemned to contract COVID-19, and possibly die because of it?