Now that Australia is re-opening, what are the numbers that count?

About a month ago, the Victorian Department of Health made a small but important change – in a tweet.

Around 8:30am, it put out the day’s new COVID numbers. But the text reporting the daily case number was small, and down the bottom of the tweet. Up top, in big bold letters: how many vaccination doses were distributed, the total number of fully vaccinated Victorians, and how many people were hospitalised with the disease (broken down into general wards, ICU and those on ventilators) on a given day.

This change in reporting reflects the state’s abandonment of the COVID-zero strategy, with Victorian Premier Daniel Andrews indicating in early September (when Victoria crossed well into triple-digit case numbers) that health advice had fundamentally changed.

“These last few days have seen a dramatic shift in the nature and the number of cases coming forward,” Andrews told reporters. “We will not see these case numbers go down.”

The focus since then has been to suppress case numbers for long enough to allow Victoria to reach the double-dose vaccination target of 80%, after which the state would ease most restrictions and learn, finally, to live with COVID-19.

Victoria, along with New South Wales (which recently reached a 90% double vaccination rate), is now living with a small number of restrictions, while the rest of the states are staggering their approaches to a full reopening.

The question we have to ask ourselves, after more than a year of tracking COVID through case and death numbers, is: what are the numbers that count now – and how do we choose what to report?

“At a certain point, it doesn’t make sense to focus only on case numbers,” says Associate Professor Sheena Sullivan from the Peter Doherty Institute for Infection and Immunity.

“While case counting when there aren’t many [cases] in the community gives us the ability to do a proper follow-up of each case [i.e., where a person acquires COVID, then their close contacts are called and told to isolate], when you reach 1000 cases a day, you no longer have that capacity.”

Sullivan says that while tracking each individual case may be the gold standard of infection prevention and control (led by America’s Centers for Disease Control and Prevention, or CDC), there is a point where it becomes impossible to keep track of daily infection rates.

Victoria and NSW have both shifted their public messaging towards prioritising hospitalisations and deaths. Yet other states, where COVID remains largely absent, continue to focus primarily on the number of positive cases a day.

“The CDC, who are leaders in terms of control and prevention of infectious diseases, last year conceded that their usual approach of following up every case and contacting each contact was no longer relevant – you just can’t employ enough people to call thousands of cases a day,” she says.

In Australia, Victoria and NSW have both shifted their public messaging towards prioritising hospitalisations and deaths. Yet other states, where COVID remains largely absent, continue to focus primarily on the number of positive cases a day. This, experts say, is not a long-term strategy.

“The possibility of eliminating COVID-19 doesn’t exist at present, and Delta is going to make it hard to break transmission strains,” says Dr Meru Sheel, Westpac Research Fellow in the the Australian National University’s College of Health and Medicine.

“Perhaps in a few years we may be able to see elimination; but now is the time to contain the outbreaks, so they don’t lead to big numbers of deaths and hospitalisations.”

Professor Emma McBryde from the Australian Institute of Tropical Health and Medicine adds that COVID-zero is no longer on the table. So many people are fully vaccinated, she says, “it seems entirely unreasonable to test those who have no symptoms, and who are unlikely to get severe COVID disease or likely to pass it on.”

“If you’re trying to achieve elimination, every case matters – this means counting asymptomatic people and isolating them. This is not where we are at.”

While experts agree that tracking hospitalisations to minimise deaths as much as possible should be the overall objective, focusing on and communicating to the public the details of each individual case is no longer helpful.

“When it comes to raising awareness among the public, we should be communicating how the health system is coping – we don’t need to know if a 12-year-old has COVID or not,” McBryde says.

Modelling predictions have also largely informed what numbers get prominence. At the beginning of the pandemic, it was predicted there would be somewhere between 50,000 to 150,000 deaths from COVID; that New South Wales would drown under thousands upon thousands of daily cases; and that Victorian hospitals would be overflowing, with the Burnet Institute projecting a peak of between 2778 and 6761 cases by 15 December, and 2022 deaths.

“When it comes to raising awareness among the public, we should be communicating how the health system is coping – we don’t need to know if a 12-year-old has COVID.”

– Professor Emma McBryde, Australian Institute of Tropical Health and Medicine

None of that has come to pass, and McBryde thinks that could be because the modelling assumed that lockdowns were working much better than they actually were.

“Most models, including my own, thought cases and deaths would continue to go up when restrictions were eased, but they haven’t,” she says. “It is worth reflecting on why they have been going down: is it that we overestimated the impact of lockdowns?”

Lockdowns only work, she points out, if people who have the virus are following the rules and are not seeking alternative ways to be sociable even within the rules. It’s possible that in “the current environment, with nearly everything open, [lockdowns have] not made as much of a difference as initially thought.”

And while Australia is still shifting out of COVID-zero mode, so far the aim appears to be keeping hospitalisations and deaths down, something that epidemiologists believe will remain the strategy until the disease becomes endemic, like the flu or the measles.

However, as we gradually open our international borders, the public health policy will need to shift to reflect the resurgence of other respiratory viruses, such as the flu and the Respiratory Syncytial Virus, or RSV, which tends to hit children the hardest.

“We need to eventually shift to a public health approach that focuses on more than just one disease,” Sullivan says.

“The UK, for instance, is seeing an increase in cases of the flu, and as people from there start to come here, it increases the chances of it circulating in Australia, where we haven’t detected influenza since April 2020.”

At that stage, Australia will be seeing a dual circulation of flu and COVID-19, and it remains to be seen whether the impact will be substantial. As with other diseases and viruses, epidemiologists will be looking for signs such as ambulance ramping and big spikes in hospital admissions (and even deaths) as indications that things are getting out of hand.

“The situation becomes alarming when hospital capacity is exceeded,” Sullivan says, “which has happened in the past with the flu, after which hospitals were ordered to cease elective surgery.”

Experts predict that jurisdictions that have largely avoided big case numbers (i.e. every state bar Victoria and NSW) have the best chance of a soft landing – but that doesn’t mean no deaths. As the modelling underpinning the reopening of South Australian borders predicts 13 deaths across almost a year, McBryde says the number will be “equivalent to other rare causes of death that happen across every society all the time”.

“There is no one magic number: as epidemiologists, we look at trends and patterns to examine the situation at the population level.”

– Dr Meru Sheel, ANU Research School of Population Health

“Thirty per million people a day die every day, and most of that is of natural causes, but some from homicide, workplace accidents, or even freak events,” she says. “We try to minimise them, but they happen every day.”

Focusing obsessively on daily COVID cases is not conducive to living with the disease, and a move away from contact updates will be more in line with how epidemiologists track all sorts of other diseases.

“We can’t just radically keep changing people’s choices for the worse in order to avoid these extraordinarily tiny risks – there’s got to be a balance,” says McBryde.

The way forward, she argues, is a much more nuanced and targeted approach: rather than testing everyone (and reporting those test numbers) regardless of symptoms and proximity, we need to start focusing on the level of virus circulating in vulnerable communities such as nursing homes, Indigenous populations and the immuno-compromised.

And while tracking incidence still needs to continue, which includes reporting positive PCR tests, McBryde points out that if we reduce the number of tests conducted per day, the proportion of cases that are detected will also reduce – potentially resulting in misleading case numbers.

Because we’re human and we like clear answers, it’s tempting to quantify everything and have a clear priority of which numbers to report. Yet Sheel says that in each setting, the health system, including hospitals, will have a different threshold, a red-line capacity number that it must stay below to cope.

“There is no one magic number: as epidemiologists, we look at trends and patterns to examine the situation at the population level, such as how many cases are there in the community, who is getting infected, who is getting hospitalised, how many are vaccinated, which populations and where the disease is coming from,” she says.