What we know about COVID-19 seems to change daily.
We asked Professor Narveen Jandu, an expert in microbiology, to give us an update on the science of the virus.
What is the current understanding of how the virus spreads?
The transmission of COVID-19 is predominantly spread through respiratory droplets from infected individuals, and can be referred to as person-to-person transmission. This type of transmission is predominantly from direct contact with respiratory droplets from infected individuals during coughing, sneezing, talking, laughing or singing in close proximity others.
There are concerns about aerosol transmission, but in most situations, this type of transmission has taken place in crowded settings. Originally, there were concerns that fomite transmission (contracting the virus from inanimate objects contaminated with the virus) was a potential way in which the virus was spreading in the community, but it appears that most cases of infection are from exposure to the respiratory droplets of infected individuals.
What are the symptoms of COIVD-19 and what fraction of people who have it do not show symptoms?
Most individuals that are infected will experience generic symptoms that are mild or moderate. COVID-19 infection often appears as a fever, dry cough and/or body aches, pains, general malaise and tiredness, and in some cases, there is a loss of smell or taste. Individuals will experience varying combinations of these symptoms. The duration and severity will also vary from person-to-person, as this depends on the age of the individual, the underlying health of the individual and viral load (how much of the virus has entered an individual’s system). Most cases of infection (80 per cent) will be mildly symptomatic or asymptomatic. The remaining 15 per cent of cases will experience severe symptomology, and 5 per cent will become critical.
What is the damage that can be caused to the body by the virus?
In the small percentage of cases in which symptoms are more robust, severe and/or critical, viral replication and physiological damage can go beyond the respiratory tract. Typically, and in the majority of cases, coronavirus replicates in the respiratory tract, which results in the most common symptoms (outlined above). Within the respiratory tract, some individuals may develop pneumonia. In the most severe cases of infection, the virus can cause pathology in other body systems, most notably the cardiovascular system, kidneys and/or the gastrointestinal system.