Diverging Interests: Covid in Australia by David Maywald

posted by Lyric Hughes Hale on August 20, 2021 - 12:00am

There's no doubt that vaccines reduce the harm from Covid and many other diseases. But recent evidence from Oxford University, Israel and the United States has changed our understanding. In terms of individual immunity, the effectiveness of Pfizer and AstraZeneca peaks about two weeks after the second dose - and then it steadily declines during the next few months. Pfizer effectiveness against delta variant infections declines from about 93% post-immunisation to about 78% three months later, and Pfizer effectiveness may be lower than AZ at four months (about 60% which is barely above the minimum effectiveness of 50% from the World Health Organisation)... Hence the drive for booster shots (with an alternative vaccine) in both Israel and the US.

Covid vaccines appear to be very effective at reducing hospitalisation and death. However, there are an increasing number of cases where fully-vaccinated people have caught Covid (referred to as breakthrough infections) and passed it on to other people. The latest data shows that a fully-vaccinated person can have a viral load of the delta variant that is as high as an unvaccinated person.

The delta variant is about 60-100% more transmissible than the alpha variant and the original strain from Wuhan. Viral load is roughly 1,000 times higher in people infected with the delta variant than those infected with the original coronavirus strain. This means that a non-symptomatic person infected with the delta variant may be able to infect others within a day or two of being exposed, but an infected person may not test positive until days 4-6. It seems to be impossible to "get ahead of delta", because it is different to previous diseases...

The NSW approaches of testing, contact tracing and lockdown hesitancy was relatively successful for 15 months. But whack-a-mole has been completely overwhelmed by the reality of the delta strain, hindered by slow implementation of restrictions and a lack of compliance (I was and remain critical of the slow NSW Govt response). Today's new 825 cases in NSW have exceeded the peak from one year ago in Victoria... The fast spread and 61 new cases in Victoria today show that delta is a huge challenge, even for states that "go hard and early". Outbreaks in Dubbo and Shepparton show how quickly delta is spreading in small manageable communities, even though the ACT appears optimistic about containing it's delta outbreak.

The hope that Australia could reach herd immunity and then relax the borders now appears to be a mirage. The national "deal" is predicated on vaccinating 70-80% of the eligible population over 16 years of age, which is about 56-64% of the total population. It will take about three more months to reach the "80% target" across Australia. Imagine the negative impact of another 80-120 daily press conferences announcing Covid cases... Dozens of countries have already exceeded these thresholds, and many of them are seeing an acceleration in both cases and deaths from Covid (take a look at the US, UK, Israel, Canada, Singapore, Portugal, Netherlands and Spain). They have the benefit of high double-dose vaccination in addition to some immunity from Covid cases in the community... Opening up after exceeding the "80%" Australian target would soon see the same acceleration in cases and deaths as these other countries are experiencing now (remember that fully-vaccinated people can catch and transmit delta, and vaccine effectiveness starts falling within three weeks of getting the second dose). The Doherty Institute modelling is based on opening-up from a low base of Covid cases (which is not currently the situation in Australia), and appears to assume static vaccine effectiveness (at odds with the Oxford study and Israel evidence). Herd immunity may be impossible to achieve with delta...

The balance of costs and benefits from lockdowns has changed with delta, because it is extremely challenging to halt it's spread (in the case of NSW the cost of reaching zero cases may be impossibly high for the community to tolerate). Children are missing out on higher quality learning/social/sport experiences, some businesses are being crippled, physical and mental health is being hurt, working parents are being asked to supervise home learning in addition to their full plate, families and loved ones are missing out on innumerable opportunities... where is the modelling to add up all of the costs and lost opportunities from lockdowns?

Delta cases are being spread by younger people, including adults under 40 years old and school children (who have had limited access to vaccines). But there have been very few hospitalisations and deaths for people under 30 years of age. There are diverging interests between age cohorts (old versus young), between different parts of Australia, and between those who bear the brunt of lockdowns versus those who are largely insulated... If the NSW outbreak becomes endemic, within Sydney or across the state, then how long will the surrounding states enforce hard borders to "keep out the risks"? I'd be very surprised if Queensland, WA or SA opened their states to NSW after getting to the "80% target"... There will be more anti-lockdown protests, more seeding events (from quarantine failures and porous borders) and we will see the diverging interests play out.