Featured researcher: Professor Catherine Bennett

Delivering the facts without the spin

Professor Catherine Bennett, Deakin’s Chair in Epidemiology within Deakin’s Institute for Health Transformation, is a leading researcher and teacher in public health, with a specific interest in infectious disease epidemiology and community transmission. During the COVID-19 pandemic, she has become a trusted and reassuring voice in the media, clearly presenting the facts around the daily case numbers and reducing anxiety and uncertainty by stripping away the misinformation and speculation surrounding the virus and its impact on our lives.

Her engaging commentary and expertise ranges from analysing and interpreting the numbers, to discussing the reasons why people can’t or won’t comply with restrictions, and the importance of facts over opinion.

Discover more about Catherine’s research and career

For the latest evidence-based comments and analysis, follow Catherine on LinkedIn

The international picture

Overview

These graphs represent the response to the waves of COVID-19 outbreaks around the world and will continue to be added. The dark green curve shows the cumulative cases, while the light green curve shows the daily reported cases. Decisions that affect the whole population or sections of the country are classed into groups – governance, community mitigation, travel and surveillance, as well as the easing of restrictions and, further down the timeline, the vaccine rollout. These graphs allow us to visualise the timeliness and effect of some of the key decisions on the containment of COVID-19 within each country.

Australia (Melbourne)

Between 2 - 9 July 2020, Melbourne entered Stage 3 (stay at home) lockdown, when daily new cases were around 60-140 per day. As daily new cases reached an average of 300 new cases per day, Melbourne entered Stage 4 lockdown, which included a 5km travel limit, and a curfew.

Within two days of declaring Stage 4, the new daily cases began to rapidly fall. The first step of easing restrictions (not counting removal of curfew) – when 5km limit was increased to 25km and some businesses were allowed to reopen - was when Melbourne was at an average of five or less cases a day, in October. Vaccinations commenced at mid-end of February 2021.

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Ireland

Between 18 September 2020 and 5 October, Ireland progressively moved to Level 3 restrictions (outdoor dining still allowed, schools open, hairdressers and some retail open with protective measures). At this time, Ireland had between 250 and 500 new cases per day. On October 21, when there were approximately 1100 new cases per day, Ireland announced Level 5 restrictions (equivalent to Melbourne’s stage 4, except that schools would stay open). Within days of announcing and scaling up the enforcement of Level 5, daily cases began to drop. A planned first step for reopening commenced when new cases were around 300 per day (1 December); small businesses, retail, gyms, hairdressers and public places reopened. Reopening continued progressively leading up to Christmas. By Christmas time (25-29 December), Ireland was seeing over 1000 new cases per day, and climbing. It was around that time that the UK variant of the COVID-19 virus was confirmed in Ireland. Level 5 restrictions were re-introduced on the 30December, and two weeks later the country had its peak of 8227 new cases per day. At the beginning of January 2021, the UK variant of the virus was detected in approximately 25% of COVID-19 tests, but by mid-February this variant was found in over 90% of the tests. Ireland is currently experiencing around 600-700 new cases per day. Vaccinations commenced at the end of December 2020.

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Singapore

Around 7 April, when Singapore was experiencing approximately 60 new cases per day, a circuit breaker lockdown was implemented, which is equivalent to Melbourne’s Stage 3 lockdown. Around 1 June, when the daily new cases climbed over their peak of 860, and began to slowly fall to around 500, the last day of the circuit breaker was announced with a slow and progressive resumption of activities such as religious worship, and small businesses reopening. Clusters that were discovered, would be contained by placing entire households of close contacts immediately into quarantine. Numbers continued to decrease until around July (around 200 per day), increased to around 380 in August and continued to come back down, with no noted country-wide restrictions implemented. At the end of September, when there were around 25 new cases a day, offices returned to work and events of up to 250 people, with safety measures, were allowed. Singapore has maintained approximately 5-40 new cases per day until now, with no large outbreaks. Vaccinations commenced at the beginning of January. Although Singapore did have a nationwide lockdown period, their approach was more localised, with anyone breaching the stay-at-home order having their visa revoked or passport cancelled, businesses not following rules being shut down even during reopening stages, dormitories isolated as clusters were detected there, and heavy fines and prison sentences given out for individuals in violation of COVID safety measures.

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Stopping the spread

Vaccine rollout

Restrictions and lockdowns

  • 31/3/2021: My summary in the Age. Now eight more QL community cases have been announced overnight - five people associated with the nurse and her sister. One other a known contact of the previous male cluster, and two still being investigated. Authorities now believe the nurse did contract the virus from work though are still waiting on genomic results. Brisbane outbreak sends us all a strong warning
    • 30/3/2021: QL update - we have two clusters stemming from two distinct index infection events associated with two returned travellers. Both had the B.1.1.7 variant, but different enough to allow us to distinguish between the two clusters. First it’s worth clarifying that QL does not have hot hotels, health hotels or SHA hotels like other states, all returned travelers who test positive are relocated into hospital instead. The original Princess Alexandria Hospital doctor who was infected on March 9 and tested positive March 12 is linked to the first cluster. In this group we have three close contacts who are PCR negative but have antibodies and so may have recovered from an earlier infection. But we do not know how they physically link back to the hospital. Maybe the latest two will hold the clue. Five cases now linked to the Princess Alexandria nurse cluster. One further new case is linked to a close contact but we don’t know from which cluster. 14 community cases now including that original doctor. Tonight a further case was reported, again linked to the Princess Alexandria Hospital. Today the CHO said they know they haven't any missed cases in the community because all the cases they have found are linked. But they are actively testing contacts so that’s not surprising. If all cases cannot yet be epi-linked to the index case, unknown cases are out there.
    • 29/3/2021: QL lockdown - So much one could say but that’s why they have word limits on articles! Let’s hope that we hear more about actual epi linkages between cases now the genomics have (so far) identified these as one cluster associated with the Princess Alexandra Hospital case from March 9. It’s the epi links, the way cases overlap in person, time and place, that tell us when and where transmission occurred. This also helps map the outbreak and the risk of their being more missed cases. Without this, the 3-day lockdown may be destined to run longer. Testing rates are up the last two days, so fingers crossed any other cases will be found through this and rapid contact tracing. Our hearts go out to all those in Greater Brisbane now, or that have been there in the last couple of weeks. COVID in Brisbane: 3-day lockdown begins as authorities scramble to find missing links
  • 19/11/2020: Experts, including Deakin University Chair in Epidemiology Professor Catherine Bennett say SA got it right, even if the measures seem overly restrictive.
  • 18/11/2020: Epidemiologists say six-day lockdown enough to contain SA outbreak
  • 16/11/2020: Catherine joins the panel to discus the Adelaide COVID-19 cluster: The Drum Monday November 16
  • 14/11/2020: How an Australian state beat its second wave of COVID-19
  • 10/11/2020: Watch as Catherine talks about how Melbourne got on top of the second wave Melbourne Crushes Covid-19
  • 9/11/2020: Victoria's achievement in bringing down daily coronavirus numbers from 700 new cases a day in August to none in the past 10 days has led Ireland and other European countries to seek our experts' advice on how the state did it. Zeroing in on Victoria's suppression success
  • 8/11/2020: “We were more sedate after wave 1 in Melbourne (according to mobility measures and number of close contacts) and will be interesting to see what happens this time. Feels really busy in places already, but to be honest we have all adapted so much to isolation so hard to judge!” After Crushing Covid, Melbourne Emerges Wary and More Sedate
  • 6/11/2020: “Victorians may be rewarded on Sunday after their perfect week of zero coronavirus cases with a more widespread easing of restrictions than had been planned.” After seven doughnut days, Victoria set to be 'much closer to normal'
  • 1/11/2020: Catherine Bennett: Now that Melbourne’s COVID-19 lockdown has ended, what’s next?
  • 31/10/2020: “Victoria may still have some work to do in communications and case management, but in all other respects we are there with contact tracing. And with our numbers down (only 1 new case today, 14-day average at 2.4 and 2 mystery cases in a fortnight), we should now be able to keep numbers down and outbreaks contained so that we never have to test the system at high case numbers again! NSW continues to have low-level community transmission with 20 cases in the last fortnight, averaging 1.4 cases a day. I am not sure why so much emphasis is being placed on “difference” when arguably we are in the same boat, although Vic has the advantage of less risk of wider community transmission for now at least as we emerge from our extended lockdown. Let’s hope both states can close off community transmission.. then we can celebrate together, move fully to prevention mode, and borders won’t be an issue!” Top epidemiologist rates Victoria’s contact tracing as the ‘gold standard’
  • 28/10/2020: Victoria and only a handful of countries have achieved zero from second wave

Masks and face coverings

Testing

Community transmission and contact tracing

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Points of view

    • 20/11/20: A leading epidemiologist has argued workers in hotel quarantine need to be paid more so that they don't work other jobs and risk coronavirus infection. Could higher-paid hotel quarantine workers better protect Australia from COVID-19?
    • 18/11/2020:  “South Australian six-day circuit breaker lockdown: let’s hope it’s enough to ensure they have found the edge of this cluster. The next few days will tell. Five generations of spread in less than two weeks makes it a challenging fight.
      They were not aware of the leak till an elderly second generation case attended an emergency department and the doctor decided to run a COVID test even though the respiratory symptoms were mild. This could have made all the difference.
      Testing the staff at med-hotels would have been better again, picking this up a generation earlier .and there might not be 4000 in isolation or an entire state locked down for six days.
      Let’s hope this works for South Australia’s sake, and because it matters a lot to the rest of Australia. It will also tell us if this short burst of extreme lockdown is a useful strategy to consider when dealing with a point source cluster that is not discovered until there have been a few generations of spread.” South Australia's 6-day lockdown shows we need to take hotel quarantine more seriously
    • 12/11/2020: “Is Victoria a model covid-19 response? Our story is one very different from what is happening in Europe now. We had the first wave contained through early introduction of six weeks of stage 3 lockdown, but we missed the start of the second wave when the virus was reintroduced from hotel quarantine breaches. We then had a large and long second wave largely driven by healthcare outbreaks, especially aged care, whilst Victoria was held in lockdown until these were eventually closed off ... and we had a public health response that could cope with opening up. Add to that a government so concerned about a third wave that it was believed we had get numbers extremely low “to keep them low”. That all ends up looking like 4 months of lockdown... and at what cost? The Victorian response must be judged on the extent and duration of lockdown, and the reasons behind the need for such a long lockdown, .. just the case number outcome.” What is behind Victoria's suppression success, and will it last?
    • 7/11/2020: “Coronavirus could "die out" in Australia entirely if New South Wales and Victoria stay on their current trajectory of low infections, according to two leading epidemiologists.” Coronavirus could disappear in Australia if NSW and Victoria maintain control over next few weeks, experts say
    • 3/11/2020: “Europe is beginning what Melbourne has only just finished: a second lockdown.” Podcast: Has Europe left it too late?
    • 25/10/2020: As coronavirus cases plummet, it's time to ask: Is Australia ready for the third wave?
    • "An opinion piece with colleagues .. we did not come up with the title and of course the comments relate to the title rather than the piece.. but I hope you appreciate the read!" COVID success will only come when Premier trusts the public
  • “Throwing some numbers around... if we have to count anything, then we may as well count in a way that captures where the real risk is (unlinked cases) and the linked cases where there is still some work to do… especially if these are casual contacts who may not yet be in quarantine.” A 14-day rolling average of 5 new daily cases is the wrong trigger for easing Melbourne lockdown. Let’s look at ‘under investigation’ cases instead
  • Doctors stoush over Victoria's extended lockdown
  • With cases stubbornly staying in the double digits, is there any light at the end of the tunnel? What was that about being OK for Xmas? Lockdown life in Melbourne shows no let up
  • “The CHO said today that once a close contact develops symptoms, DHHS will now consider them to be presumptive cases before they receive their tests results, and follow up their contacts immediately. So contacts of contacts will then be notified and asked to isolate as a precaution in case they are infected and heading into their pre-symptomatic infectious period. That’s exactly what’s needed when we have rapid spread with nearly 30 cases in 10 days in first and second level contacts. It sounds like DHHS might do this more extensively in outbreaks now - The real advantage of having lower numbers. The complexity of this outbreak shows what was happening many times over when there wasn’t the clarity or resources to see and investigate outbreaks with cases embedded in amongst 100s of new cases a day. We are in a whole new world now.. still extremely hard work for the department, but much more possible for the health teams to contain these outbreaks.” Victoria enters uncharted waters, urged to trace contacts of contacts
  • "Time to gather the information needed to fuel the difficult but necessary debates about how we live with the virus - we had limited choices when COVID-19 was such an unknown, but all action, and inaction, comes at a cost (lives, health, economic and the myriad of societal impacts), and now we must comprehensively evaluate our strategies." Lockdown is working, but is it excessive?
  • "We know hotel quarantine is not the perfect option, and not just in Vic. WA is a test case for us to determine how safe home isolation is for returned travellers, especially coming from low risk countries. If home isolation was successfully for many of our 20,000 known positive cases in wave 2, and for the quarantine of their close contacts who had a much higher risk of being positive than travellers returning from low risk countries, then this is an option to consider. Let’s hope evaluation of compliance in WA shows this to be a workable option, i’m sure Aussies wanting time come home (even from interstate) will be very relieved if this is deemed safe!" Coronavirus experts cautiously support Scott Morrison's plan for 'safe' international arrivals
  • Health experts question 'incredibly conservative' road map
  • “More modelling? The Burnet Institute team’s nuanced agent-based model calibrated to our second wave in Vic has more to offer. They found a 41% risk of another wave if we had jumped to the final roadmap step yesterday with our 14-day average at 22 (the previous conservative model said 62% for 14-day av. of 25).
    Many are now asking whether we still need the 5km rule. Or when will it be safe to move to step 3, and should the 14-day case count thresholds for this step be updated. These are the kind of scenarios that could be explored using this new model.
  • The cases seeded into the model should reflect the different mix of case risk we have now (92% are linked and most therefore likely to be in isolation/quarantine when tested), but could be really helpful in guiding decisions on thresholds and timing of steps, as well as whether the 5km rule could be lifted. This is stopping some families from meeting outdoors or permitted businesses opening if clients aren’t local.
    It could also help people adapt to the roadmap changes (inc lifting of curfew etc), and help allay fears they may have about opening up. This will be very safe, our detection and response systems too, so we need to bring the people along with us who no longer believe that!” Melbourne's five-kilometre rule: is it really worth it?
  • “Two months ago there was consensus among epidemiologists that to open up we would need new case numbers in low double digits and mystery cases to single digits. Since then it has all gone a bit crazy, but even after the road map was announced, there has been agreement that 5 cases was too ambitious and 10 cases a day is manageable. Over 70% if Vic’s cases are known to be linked when first reported, and therefore in people already in quarantine, and 85% of our cases under investigation are also linked eventually. We by now must have less than one mystery case a day on average (judging from changes in 14 day total). So why is a small number of contained but persistent outbreaks and 5 community cases a week not manageable? Sure we don’t want months of chasing cases like NSW has had to do, but continuing strict lockdown when we have already had 15 or more incubation cycles under it is clearly not the answer. We need to start easing restrictions, keep testing up, have fast and comprehensive case and contact follow-up, and remember the basics - distance, hygiene and masks. Then we can focus on prevention, early warning systems and monitoring to stay safe." What Australia needs to do to avoid a third Covid wave
  • Chatting again about all things Covid-19 with Tass and Fiona on Joy radio’s Saturday Magazine Catherine Bennett, Epidemiologist
  • “Divisive speak is dangerous - true always but particularly so in a pandemic. Opinions are being polarized; open-up completely or strict lock-down, you’re onboard or “you think it’s over because you want it to be over”, this virus is wildly infectious and cant be controlled without complete lockdown or you don’t believe it exists. Anyone with an opinion that doesn’t fit with either extreme is placed in to one to suit the commentator’s argument. These are worrying times. Most recently the narrative at the daily press conference is about regional and peninsula folk being terrified of Melburnians because of their “vastly higher amounts of virus”. Regional Vic’s 12-day av is a very low 1.9 cases/million, and the metro rate is also very low at 7.9 cases/million (half already in isolation). The Health Dept say they can finally see community transmission chains that were there all the time but hidden behind high numbers (data analyses could have shown sooner?). Stage 4 is about suppressing risk of transmission beyond these pockets where infection persists, creating the optimum backdrop for the Dept to do its work. 9 weeks in lock down has not been enough time for this (5-12 incubation periods), let’s hope another couple of weeks is.” - Catherine Bennett's LinkedIn
  • RMIT ABC Fact Check: Were NSW's coronavirus numbers higher than Victoria's thresholds for lifting curfew, as Scott Morrison said?
  • Has Australia really had 60,000 undiagnosed COVID-19 cases?
  • Another week, and we will know more about our October in Melbourne. The Age has taken the lighter moments from today’s press conference to build hope. Also a useful discussion on whether those identified in breach of CHO rules in contact tracing interviews should be fined. Our enforcement strategies have placed us in a difficult situation - respect privacy, open up conversations in order to close outbreaks down, or issue fines. This is part of a bigger public health communication conversation about the way we engage community. Public health communication strategies needs to provide transparency, clarity and certainty, so that people come forward for testing quickly, then have the conversations to allow us to chase any transmission - without rapid testing and information handover, it is that much harder to contain outbreaks. Outbreak control always works better if enforcement is a last resort, and that is something we should try to find ways to avoid going ahead. Premier raises hopes of easing restrictions sooner than planned
  • What is ‘herd immunity’ and what role does it play in a pandemic? Explainer: Reaching herd immunity in a viral pandemic
  • “Think before you voice an opinion — consistent messaging is critical in a public health crisis. Expert debate can be valuable, but publicly opposing current interventions on the basis of opinion rather than fact can reduce efficacy by undermining public confidence, and therefore compliance... both of which are already harder to garner in a second wave.” Latest restrictions became a self-fulfilling prophecy

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About the daily numbers

  • 27 November 2020: "Twenty-eight days without new cases for Victoria, and hopefully NSW will announce today that they have reached 20. Adelaide looks like they have this cluster under control (contacts of contacts pays off yet again) with only one new case reported. Victoria has reported some positive sewerage tests and so we do need to keep our testing rates up, and we need to practice those precautions that mean even if the virus is out there, it won’t have the opportunity to take off quickly. We have this Australia, but we all have to keep actively working on it individually and collectively to hold on to this... the positive wastewater results in our south west are a reminder."

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‘Disease detectives’: The role of epidemiologists during a pandemic

Epidemiology is the study of health and illness in human populations, from the occurrence and distribution of disease and the factors behind to the dynamics of infectious disease outbreaks. Epidemiologists use the information they gather to design and test interventions for prevention and control, promote public health education and inform government policy making.

Epidemiologists are invaluable during a pandemic because of their skills in gathering information about disease in a population and using it to anticipate what’s needed, identify risks and prioritise health and other resources.

Listen to Catherine talk about life as an epidemiologist: So you want to be an epidemiologist?

Become an epidemiologist