In the Sydney morning Herald.
By Professor Mike Toole AM and Professor Brendan Crabb AC
In the past two weeks, Sydney has recorded 125 new locally acquired cases of COVID-19. This is more than each of the Crossroads and Thai Rock clusters. While far from being a second wave, the cluster that began in Avalon (or maybe Belrose) remains of concern. New infections have been acquired outside the northern beaches at pubs in Erskineville and Circular Quay, a workplace in the CBD and a cafe in Paddington. The potential for further transmission is real.
The impact of this outbreak on the lives of Sydneysiders has been significant. As of Sunday, the NSW Health website lists 164 exposure locations and 40 public transport routes where people may have been in close contact with an infected person. The economic impact, such as reduced CBD Boxing Day sales and interstate travel, is likely to be substantial. And, of course, it may continue for some time.
So how does the response to this outbreak rate against the hard lessons we’ve learned in Australia and overseas? The quick restriction of movement in the northern beaches compares favourably with Victoria’s tardy reaction to the emergence of a second wave in late June. However, it rates as “lockdown-lite” compared with the South Australian government’s response to the Parafield cluster. The actions of that government, although based on some misinformation, did limit the Adelaide cluster to just 22 people.
As we await the rollout of a vaccine, what interventions do we have in the toolkit to manage an outbreak like we’re witnessing in Sydney?
Broadly speaking, there are two strategies. The first is an effective test-trace-isolate system. Clearly, this is working well in Sydney with record numbers of daily tests, reaching almost 70,000 on Christmas Eve. That essentially means that all infected people who get tested are isolated and so are unlikely to spread the virus. But no jurisdiction, including NSW, which justifiably has great confidence in its capacity, relies totally on this approach.
Everyone adopts a second strategy that involves preventing transmission between people who are not self-isolating and may not have symptoms. It includes hand hygiene, physical distancing, improving ventilation where people meet, and mask wearing. Physical distancing is the most effective. This can be achieved by implementing restrictions on movement and interaction.
A study published in the Medical Journal of Australia by Burnet Institute researchers demonstrated that the introduction of Stage 3 restrictions (similar to those now in place in the northern beaches) on July 8 in metropolitan Melbourne reduced the effective reproductive rate from 1.75 to 1.16 just prior to the introduction of stricter measures in late July. This equated to preventing around 20,000 new cases.
If the rolling 14-day average of new cases in NSW (currently 9) does not decline in the coming days, consideration should be given to extending stay-at-home restrictions of this sort to Greater Sydney.
Professor Raina MacIntyre has precisely described in these pages potential super-spreading events during Christmas and New Year celebrations. The impact of interactions during the Christmas period on transmission is not yet known. New Year’s Eve poses a special challenge, not so much through outdoor events but from gatherings inside hospitality venues that can still accommodate up to 300 patrons. As we know, there will be a lot of chanting and the traditional loud singing of Auld Lang Syne at midnight. If Stage 3-like restrictions aren’t extended to Greater Sydney, caps on indoor venues should be reduced significantly especially on New Year’s Eve – even if the rolling 14-day average declines this week. Outdoor celebrations should be strongly encouraged.
And then there are masks, which the NSW government has resisted mandating despite calls from many public health experts. Respected health agencies like the World Health Organisation and the US Centres for Disease Control and Prevention now recommend that the public wear masks when there is local community transmission. To be fair, NSW Health is supportive of masks and strongly encourages their use. It is the matter of mandating that has not been adopted.
A Burnet Institute study found that mandating masks in Melbourne led to mask usage increasing from 43 per cent (when recommended but not mandated) to 97 per cent.
This was associated with a decrease in the rate of infections by between 22 and 33 per cent. Mandating masks was not only highly effective, it was introduced without a punitive attitude and with little pushback. Very few fines were issued for non-compliance – 8 per cent of all COVID fines in the second wave and half of those were issued at anti-mask rallies. Police were more likely to give the non-wearer a mask than a fine. Peer pressure was the main driver of compliance.
The COVID outbreak in Sydney is at a delicate stage and the city is not yet out of the woods. Scenes of tightly packed revellers on Bronte Beach on Christmas Day and unmasked crowds in indoor suburban shopping centres on Boxing Day highlight the ongoing risk. While NSW Health authorities are clearly supportive of both movement restrictions and mask wearing, our view is that neither has yet been used optimally to complement their testing regime.
With what we know is effective in the Australian context, there is every chance that a short four-to-six day, Sydneywide “Stage 3-like” restriction, plus the mandating of masks, if implemented a week or more ago would have seen this outbreak largely ended by now.
Short-term pain for longer-term gain. Instead, the outbreak rumbles along, bringing with it ongoing movement restrictions, economic disruption and the ever-present threat of a substantial second wave.
The magnificent efforts of NSW contact tracers and the outstanding response of the NSW community have averted the worst so far. But there is more that can be done to douse the Sydney spot fires and minimise the risk to health and economic disruption. Starting with an immediate mask mandate.
Professor Mike Toole is an epidemiologist at the Burnet Institute. Professor Brendan Crabb is the Director and CEO of the Burnet Institute.