Why the Coronavirus could be spreading exponentially
The Australian Government continues the argument that ‘Case numbers of Covid-19 in Australia are dropping’ and that we are ‘flattening the curve’ of transmission. Until we can test everyone with symptoms this is a potentially dangerous message that needs to be stopped. Exponential curves always appear linear in the beginning, or in plain English, at the beginning of any pandemic, the spread initially can look slow but the numbers can be secretly growing and we don’t realise it until our health systems are about to be overrun (America, especially New York, is the best current example). I have outlined below why Covid-19 is such a tricky disease to monitor the spread of in the first few months of the pandemic arriving on Australian soil:
- There is a large lag time between infection and symptoms and very large lag time between symptoms and death. It takes on average 7 days to become symptomatic after a person has been exposed to Covid-19, but they can spread the virus for 48 hours before they become symptomatic. It may take another 7 days after symptoms to get sick enough to require hospitalisation and it can take 3-6 weeks after symptoms have developed to die.
- In Australia we currently have a testing criteria confirmation bias. Until only a few days ago, the testing criteria was that to be tested, you had to have recently returned for overseas, been in contact with a known Covid-19 sufferer or be sick enough to present to hospital. This means a raft of people with mild symptoms do not meet the testing criteria.
- The test for Covid-19 is an antigen test. It lets you know if you have an active infection. This test will be negative after you have fully recovered from the virus. Australia needs to make a huge amount of these tests available, along with the antibody test that can tell you if you have had the virus and are now likely immune. Only the antibody test will tell us how many people actually had the disease and went completely undiagnosed.
- Asymptomatic carriers: Carriers can have a wide range of experiences, from being asymptomatic, to mildly unwell, to acutely unwell to needing intensive care treatment. Asymptomatic carriers can be moving around in the community, spreading the disease completely unaware.
- The disease is spread in respiratory secretions as aerosol contact and spread in faecal material. This means that a carrier can spread the virus in their breath and spit (including cough and sneeze). If they touch their mouth, their hands are contaminated. They can also spread the virus in their stool which has huge implications for childcare centres, where children are toilet training or having nappies changed. Even primary school aged children are generally not capable of having the hand hygiene required of them to not spread the virus to their classmates and friends (and families)
- Infected people may infect on average 2-3 people, but some people are super spreaders and others may spread it to nobody. We know that children tend to be asymptomatic or have mild symptoms only. For example, an asymptomatic toddler at day-care could potentially infect the whole room they are in during the (approx.) 7-14 days they are shedding the virus, in turn, every infected child from that day-care facility would infect their whole household.