case total lockdown australias lessons world

CASE TOTAL LOCKDOWN AUSTRALIAS LESSONS WORLD FULL

With measured steps, we managed to open up, having successfully eliminated all the community transmission caused by the first wave. Mercifully, though, with the big testing blitz in April failing to detect many more cases, we knew the lockdown worked.

We may never know the true size of the first wave. But the serious cases that did appear in hospitals - the tip of the iceberg that was community transmission - made it clear there was a problem. Health authorities didn’t test for community transmission in the first wave because they were anxious to focus testing capacity on high-risk returned travellers and their close contacts. Some of the new cases came as no surprise - authorities were still wrapping up the Cedar Meats outbreak, after all, and small numbers were continuing to appear, with the odd, refreshing zero-case day. The beginning of Victoria’s second wave was buried in the tail of the first wave. We didn’t know all this at the start of the pandemic, and the clustering transmission only became dramatically evident in wave two. Like the reproduction number, k depends on local population characteristics (demographics, population density, number and size of high-risk transmission settings) and the interventions made by health authorities and governments. SARS and MERS outbreaks, also caused by coronaviruses, featured cluster transmission and in fact had even lower k numbers - and hence greater clustering - than the virus responsible for the current pandemic. Flu, for example, has a higher k value than SARS-CoV-2 (the virus responsible for Covid-19) and spreads more evenly through the population if people aren’t immune. The lower the k value, the smaller the proportion of cases responsible for transmissions. This figure has not been routinely reported in Australia, but it is important for Covid-19 because it describes how much a disease clusters. So we use another metric as well: the dispersion factor, or k.

CASE TOTAL LOCKDOWN AUSTRALIAS LESSONS WORLD FULL

We now know that the number of cases one person infects can vary from zero to one hundred or more, but we also know that an average doesn’t tell the full story. Shorter, stricter lockdowns can work as circuit-breakers in established outbreaks when transmission rates have started to creep higher.Īs a measure of the epidemic, the R number has the drawback of being an average. Generally the advice on lockdowns is to go early and go hard four to six weeks covers up to eight average incubation periods, and is seen as sufficient to close down community transmission while testing facilities are moved to surge capacity and workplaces prepare to operate in Covid-safe ways. We reduce R by putting in place interventions including the individual precautions of distancing, hygiene and masks, as well as population-level restrictions such as closing hospitality venues, retail outlets and other services deemed non-essential. Get R below one, and the outbreak peters out. Once you have 200 cases, you will quickly get to 400 and then 800 within the space of just ten days. Uncontrolled, the R value for this coronavirus is somewhere between two and three, depending on the setting, which means the caseload more than doubles each five to six days. A reproduction number of one means that each case infects one other person on average above one, the outbreak will take off exponentially. As we all know by now, this number captures how many new people each case infects on average, and roughly corresponds to the relationship between the number of new cases today and the number we had one incubation period ago (the five to six days it takes for a person to become infected following exposure). Of the key metrics epidemiologists employ to describe an epidemic, the one most commonly cited is the effective reproduction number, or R. By contrast, most infected people don’t pass on the virus at all. These happen when a symptomatic person with a high viral load is coughing, sneezing or talking loudly in a group of people in a poorly ventilated environment. Between 10 and 20 per cent of cases are believed to be responsible for 80 per cent of infections via “superspreader” events. We need to bear in mind one striking characteristic of this virus: it spreads in clusters.

That makes it a good time to look back at what we learned from the first wave to guide us through the second, and what more we’ve learned from the second lockdown, one of the longest and strictest anywhere in the world.

We are more than one hundred days into lockdown here in metro Melbourne - and it’s been going on even longer in the unlucky postcodes where the virus landed after the hotel quarantine breaches.

Case total lockdown australias lessons world