The Univeristy of Melbourne The Royal Melbourne Hopspital

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24 Jul 2020

Are we nearly there yet? When will COVID-19 case numbers decrease in Victoria?

Written by University of Melbourne Professor Jodie McVernon, Director of Epidemiology at the Doherty Institute.

Just over two weeks into lockdown, Melburnians are understandably disheartened to see daily COVID-19 case counts sitting stubbornly in the hundreds. Compliance with personal hygiene and behavioural recommendations is improving, mobility in the community has decreased and people are staying at home more, as requested. Why aren’t the numbers coming down yet, and what more can be done to bring the virus under control?

Since its emergence in Wuhan late last year and subsequent global spread, we’ve repeatedly seen that COVID-19 is a highly contagious infection that spreads rapidly between people in crowded environments. Modelling undertaken early in the pandemic made it clear that a combination of public health (testing, isolation, quarantine) and social (hygiene, physical distancing, movement restrictions) measures would be needed to suppress transmission to levels that would keep cases within the capacity of the health system.

The virus hasn’t changed, and as we see from other countries like South Korea and Hong Kong where initial control was excellent, it’s challenging to maintain low levels of infection over the longer term as social restrictions are eased. We need to maximise the effectiveness of all the interventions we have at our disposal to beat this virus back.

Early identification and isolation of cases is absolutely critical for an effective public health response, as keeping infected people from mixing in the community means they can’t continue to spread infection. High testing rates are needed to find cases, but not all tests have the same value; so just doing more is not necessarily better. People with respiratory symptoms are much more likely to be positive for COVID-19 than those with no symptoms, but we’re aware that a relatively low proportion of such people are presenting for testing nationally. The key public health message in Victoria right now is to encourage all people with respiratory symptoms to isolate themselves, presuming they might have COVID-19, and to get tested for the infection as soon as possible.

To help people follow this advice, we need to understand the reasons why they may be reluctant to do so. It’s clear that people in insecure employment, or without sick leave entitlements, face significant financial hardship if they comply with isolation requirements. Recognising this, both Queensland and Victoria offer a one-off payment to help cover this period for individuals testing positive for the virus. Victoria has recently added a supplementary payment to cover the window between testing and receiving the result. Other access barriers should continue to be explored to support the public to contribute to this vital public health measure.

Close contacts of an identified case are tracked down by ‘disease detectives’ and required to go into quarantine even if they’re perfectly well. This is because they may be silently incubating the disease and can be unknowingly infectious in the days before symptoms might be observed. Again, the faster these people can be identified and prevented from mixing in the community, the better our chances of preventing onward spread. So it all comes back to finding those cases as early as possible in the first place.

On the social side, the second time around, it’s understandable that there’s a sense of lockdown fatigue in Victoria, but we know it’s an incredibly effective way of reducing COVID-19 spread in the community. All of us with only ‘four reasons to leave home’ can help to protect ourselves and our loved ones by following these simple rules to minimise movements in the community and reduce non-essential contacts. Limitations on social mixing obviously reduce opportunities for infections to spread, but also make tracing contacts a shorter and simpler exercise when cases do occur, as there are fewer to track down.

Maintaining physical distance from other people, hand washing, cough and sneeze hygiene, and environmental cleaning are all proven to reduce the risks of all respiratory infections and are just good general practice. Mask wearing by healthy people in public places has been mandated in lockdown areas this week. Alone, a non-medical grade mask may reduce the risk of infection by about 10-20%, so it’s certainly not a licence to get out there and return to life as normal. But in the context of all the other measures that are in place, it’s the ‘sprinkles on top’, adding that little bit of extra protection that could help us turn the corner.

At the moment, combined public health and social efforts in Victoria have reduced infection spread to an effective reproduction number of about 1. This means that on average, every person currently infected with COVID-19 in the population is making one other person infected. At this rate, case numbers will stay steady, but they won’t go down – making sure people with infections are isolated earlier will make a substantial difference. Each of us has the power to help make our community COVID-safe, and by working together we can drive the rate of infection down and get ourselves back out of lockdown.

Note: This work is licensed and available for republishing under a Creative Commons Attribution-NoDerivatives 4.0 International License.