As VIC and SA join NSW in imposing new restrictions, Australians are reckoning with a jarring repeat of yet another lockdown. In between home-schooling restless children, enduring endless Zoom meetings, and suffering from pandemic fatigue, the uncertainty of this new outbreak has left Australians with more questions than answers.

Today, we provide objective answers to three questions that may be on your mind:

    • Are we in a COVID-19 third wave?
    • How bad could it get?
    • What does this mean for Australia?

Are we in a COVID-19 third wave?

Unfortunately, it seems so. Recent modelling by the University of Melbourne’s Intervention Unit paints a bleak picture, with the NSW lockdown expected to last until September.

Due to the many factors contributing to the scale and duration of outbreaks, COVID-19 is an unpredictable beast. However, we can analyse historical pandemics, such as the Spanish flu, to give us some insight.

The Spanish flu outbreak lasted between 1918-1920 and infected one-third of the world population. While the biological make-up of the Spanish flu and COVID-19 is different, we can draw some parallels:

    • The Spanish flu and COVID-19 transmit via respiratory droplets and the contact surfaces
    • Both pandemics occurred in an interconnected world: COVID-19 happens in a time of globalisation and frequent international travel, while the Spanish flu existed during a period of global war
    • In both situations, governments enforced physical distancing and school closure interventions

These similarities mean that the Spanish flu pandemic one century ago can teach us important lessons about the way we approach this new outbreak.

Analysing the Spanish flu reveals one clear lesson: avoid complacency.

The Spanish flu arrived in three distinct waves (Figure 1), which show that even after the virus is ‘under control’, future outbreaks still pose a potent threat. Worryingly, the first two waves of the Spanish flu eerily mirror what we have experienced with COVID-19 so far (Figure 2).

Figure 1. The three waves of the Spanish flu

Figure 2. Daily new confirmed COVID-19 cases per million people

Therefore, the worse may not be behind us as cases in NSW linger in the triple digits. Australians should remain vigilant in this new outbreak.

In fact, three factors suggest the outbreak on our hands could become far worse than the previous two waves.

How bad could it get?

  1. More contagious Delta variant

The Delta variant is a mutated form of COVID-19 that is 50% more transmissible than the Alpha variant strain. While the evidence about the severity of the Delta variant is inconclusive, some studies suggest that the Delta variant may be correlated with more hospitalisations. Therefore, the Delta strain, which constitutes 93% of Australian COVID-19 cases, presents a significant health threat.

Figure 3. Proportion of different COVID-19 variants in Australia over time

2. Lower levels of adherence to lockdowns

Just as the potency of the virus is increasing, the public’s fear of the virus is reducing. It’s simply human nature, we have lived under the spectre of COVID-19 for 18 months now relatively unscathed. Apathy is setting in for many Australian’s who are becoming tired of restrictions and numbed by the daily coronavirus updates. So as we enter another lockdown, more people are violating the rules imposed by state governments. Violation of the rules that are there to protect us will have obvious consequences for the severity and duration of this third wave.

3. Low immunity levels

Compared to other developed countries, the Australian population has low COVID-19 immunity levels. Therefore, Australian communities are uniquely vulnerable to this outbreak snowballing into a third wave.

Australia’s low immunity levels are due to (1) lower rates of previous COVID-19 infection and (2) a slow vaccine rollout.

Firstly, Australia has lower rates of previous COVID-19 infection because its past suppression strategy has been highly effective at containing infections, hospitalisations and deaths. Australia’s successful suppression of COVID-19 has been a function of fortunate circumstances and effective policy. As an island country with a low population density, Australia is less susceptible to virus outbreaks. In addition, the government took early action on border closures and introduced effective contact tracing, which was necessary to help further restrain the spread of COVID-19. Australia’s suppression of COVID-19 has been especially remarkable compared to the severity of the pandemic in other Western countries such as the UK and the USA.

However, the lower rate of infections also means that many Australians lack natural immunity to COVID-19. This contrasts with the UK, which has high natural immunity levels due to the country’s failure to suppress COVID-19 cases in the first two waves.

Secondly, Australia’s vaccination rollout pales in comparison to many other countries. Only 16.1% of the Australian population is fully vaccinated, compared to the UK and Canada, where more than half of their people are fully vaccinated. Given Pfizer and AstraZeneca are still effective against the Delta variant, low inoculation rates leave Australia in a precarious situation compared to other countries.

Figure 4. COVID-19 vaccine doses administered per 100 people around the world

Figure 5. Share of people who received at least one dose of COVID-19 vaccine

The combination of lower natural immunity and low inoculation means that Australia is uniquely vulnerable to this outbreak of the Delta variant. Compared to Chile and Israel, which were among the first countries to achieve herd immunity, Australia is far from being safe from a third wave.

What does this mean for Australia?

Australia should brace for a longer lockdown. With a more contagious variant, lower adherence to lockdown restrictions, and a low base-level of immunity, there is every chance that this third wave will be longer and more severe than the previous two. Modelling shows that the NSW lockdown may need to run to September to sufficiently reduce community transmission. Therefore, businesses and households should plan accordingly to weather the storm.

We also expect health advice for the AstraZeneca vaccine to change. The government has already begun encouraging younger people to get vaccinated with AstraZeneca, where the Pfizer alternative is unavailable. We expect health officials to echo this advice in the future. This shift is not the result of political pressure but the necessity of public health. As COVID-19 exposure increases, the risks of contracting the virus increase; therefore, being inoculated becomes more valuable to personal and community health. When COVID-19 exposure reaches a sufficiently high level, the benefits of vaccination will greatly outweigh the potential risk due to thrombosis with thrombocytopenia syndrome (blood clots). We predict that the health authorities will adjust their guidance accordingly.

While this dreary forecast may feel like a nightmare-ish episode of déjà vu, there is a silver lining: this time, we have vaccines. As long as Australians continue to get vaccinated and adhere to lockdown measures, we may finally emerge from this outbreak and bid farewell to COVID-19 lockdowns… hopefully, for good.