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.

Listen  to Catherine chat about all things COVID in a special episode of the Healing Health podcast, presented by Deakin's Institute for Health Transformation.

Discover more about Catherine’s research and career

Read all of Catherine's articles for The Conversation.

For the most up-to-date evidence-based comments and analysis, follow Catherine on LinkedIn

Read more about vaccine rollout

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Stopping the spread

Restrictions and lockdowns

  • 17/8/2021: The unlinked “mystery” cases keep coming in Melbourne and we are still finding a third of new cases only after they are infectious. Add those two things together and it translates to even more exposure sites – and that means more cases. This is the vicious cycle created by the speed of transmission of the Delta variant. It is awful to confront the idea of yet more weeks of lockdown — even more so as they come with added layers of rules and enforcement — but the reality is we are confronted by a very different version of the virus than that which led to our lockdown this time last year. Delta has shifted the goalposts and only a team effort can beat it
  • 12/8/2021: Delta danger means lockdown extension crucial to contain spread
  • 7/8/2021: Victorian lockdown likely to be extended as cluster sources remain unknown "We must close these two loopholes in the management of primary close contacts. This is more critical than ever with Delta making it unlikely that primary close contacts can be identified and isolated before they become infectious.
    In Victoria last month those people that we know contracted the virus by attending an event or game that a case was at were infectious for 1.7 days on average before starting quarantine.
    The same would apply to any “silent cases” that went undetected among the 1/4 or more of primary contacts who quarantined but did not get tested. If there were public exposure sites linked to these missed cases, then they were missed too.
    All household contacts of primary close contacts are automatically quarantined. But by quarantining with an untested primary contact who is actually a case, they are very likely to become infected too, lagging some days behind.
    Household contacts of a primary contact who hasn’t tested positive, or hasn’t tested at all, won’t be tested at the end of quarantine if the primary contact has a negative test then - which they will even if they were a “silent case” as it would now be more than 2 weeks since their exposure and they will have cleared the infection. Their household contacts are then released… untested and potentially still infectious.
    All primary contacts must test at the start to ensure they are were not infectious whilst in the community. We are told this might be a barrier and discourage contacts from coming forward, but surely 14 days of quarantine is the greater deterrent. That said we should make testing easier, via home visit, given the enormous potential cost of missing a case.
    Secondly, all household contacts of a primary close contact should also be required to test on day 13. Even if the primary contact does always get tested, then there is always a chance a primary contact is still incubating at test 1 so the test result is negative, and then the infection has cleared by day 12 so they test negative again, but infected their household contacts in the meantime.
    We risk unrecorded exposes and transmission opportunities at both ends of quarantine if we don’t get this right. If thousands of people are going to do the right thing by quarantining.. let’s make it count."
  • 5/8/2021: Victoria will enter its sixth lockdown from 8pm on Thursday in response to the emergence of new mystery cases of COVID-19 in recent days. Contact tracing is no longer enough to contain an outbreak of the Delta variant – people who have contracted the virus just can’t be found fast enough. Lockdown six needed to tackle mystery cases
  • 2/6/2021: Tough but necessary measure to tame the beast
  • 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

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Community transmission and contact tracing

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Masks and face coverings

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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.

More details about the international picture

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.

Click here to view the graph

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.

Click here to view the graph

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.

Click here to view the graph

‘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