Realistic goals for COVID containment
This week’s expert:
Prof Raina MacIntyre, Head of the Biosecurity Program at the Kirby Institute, University of NSW
Drawn from Dr David Lim’s interview with Prof Raina MacIntyre on the Healthed Podcast, ‘Going Viral’.
• ‘Eradication’ of COVID-19 is often discussed as an aim for Australia. However, this displays a misunderstanding of the term eradication. By definition, eradication means the global absence of a disease.
• Small pox is the only disease that has successfully been eradicated
• Currently the world has two eradication goals – polio and measles. The eradication of polio appears to much closer than that of measles. Currently there are only a few hotspots where polio has occurred with most countries appearing to have successfully eliminated the disease. However, last year there were huge epidemics of measles in a number of countries.
• Generally diseases suitable for an eradication goal do not have an animal host (such as originally with SARS-CoV-2)
• Also the existence of asymptomatic transmission, as with COVID-19 makes eradication very difficult
• ‘Elimination’ of COVID-19 is another phrase often discussed in the context of what Australia should be aiming for. Again this can be confusing because, as yet, there is no clear definition what constitutes elimination. What is agreed however is that the factors that would make up elimination would include a low incidence of disease, high levels of immunity in the population and an excellent surveillance system. Our low infection rates mean we have no chance of developing herd immunity, and even in those countries with a much higher prevalence of disease, their herd immunity still appear poor. Therefore, for COVID-19 elimination is very unlikely to be possible until we have a vaccine.
• Advocates of a hard ‘elimination-strategy’ are commonly advocating a hard ‘lock-down’ strategy as a means to contain viral transmission where outbreaks occur.
• Until we have a vaccine, this current ‘brakes on, brakes off’ cycle – with strict lockdowns occurring in areas of outbreaks – is likely to continue. This is necessary to try and contain the inevitable exponential spread of the virus in the community, as the majority of the population remains vulnerable.
• Because of Australia’s success in containing the virus initially, it has become more difficult to convince people of the reality of the threat and the need to continue to take preventive measures. Health professionals need to continue to reinforce the necessity of protective measures through advocacy, example and relaying the conviction of how easily this disease could overwhelm our patients’ lives, livelihoods and the health system as a whole.