Inside Story

Means to an end

When can we say an epidemic is over?

Daniel Reeders 14 December 2022 1364 words

Incidence versus impact: an outdoor exhibition by photographer Phoebe Powell acknowledging the work of staff at Melbourne’s Parkville Biomedical Precinct. James Ross/AAP Image

China has finally taken decisive steps to end its zero-Covid policy, which mandated lockdowns and quarantine wherever Covid-19 was found. (Everywhere, that is.) Despite widespread opposition when the policy was in force, the sudden reversal has provoked a degree of whiplash, with residents staying home to avoid being caught in the wave of infections that will inevitably follow.

China was the last country to pursue a zero-Covid policy, and its reversal poses an important question: when can we say an epidemic is over?

If social media trends are anything to go by, the answer is “not yet.” The hashtag #CovidIsNotOver is still doing solid numbers. A vigorous movement is calling for a return to #ZeroCovid, including mask mandates and lockdowns. One key “Zero,” Burnet Institute head Brendan Crabb, recently described Victoria’s Covid policy as “pro-infection.”

The tone is passionate, often verging on hyperbolic and occasionally crossing over into outright toxicity. An opinion piece by Broome physician David Berger suggests only the Zeroes perceive or indeed care about the ongoing harms of Covid.

The Zero discourse is framed in two ways. The first is a justice claim: that the pandemic is not over until and unless we fully protect the most vulnerable people in society, particularly people with frailty, disability or chronic illness that increases their risk of severe illness and death from Covid-19.

The second frame rests on the risk of long Covid, which can strike people who are young, healthy and otherwise non-disabled. Advocates of this frame claim that repeated Covid infections increase the risk of long Covid, which means that everyone should be doing everything in their power to avoid exposure.

As a public health practitioner I have a lot of time for the first frame and serious doubts about the latter. It’s clear that our state and federal policy of “learning to live with Covid” privatises the risk of severe illness for a significant minority of the population. People in this group can only do so much to protect themselves.

We need to have an honest conversation about the sacrificial logic of “living with Covid” and its implicit view that the convenience of the many outweighs the right of the few to life itself. Although commonly described as “eugenics,” this policy is less about who gets to reproduce and more about necropolitics — governmental power and policymaking over death and dying.

The difficulty here is that “ought implies can,” and we just don’t have strategies to reliably protect vulnerable people from exposure, infection, serious illness and death. As China demonstrates, highly infectious strains like Omicron can circulate even amid aggressive lockdown and quarantine practices.

Studies of mask use in the real world, meanwhile, show relatively modest efficacy — nothing like the efficacy rate assumed in modelling studies. To reduce the risk of severe illness in immune-compromised people we may need better vaccines and widespread pre- and post-exposure strategies using monoclonal antibodies, antiviral medication and other treatments.

That said, one of the biggest causes of excess deaths from Covid-19 is the failure to fully vaccinate. Most people benefit from vaccination — including many people conventionally described as immune compromised. (Covid vulnerability is concentrated among people on B-cell depleting therapies.) Victoria’s chief health officer reports that 40 per cent of recent deaths occurred among the 2 per cent of the state’s population who are wholly unvaccinated.

Many of the remaining deaths, particularly among the elderly, involve people who have not received boosters. Booster provision remains stubbornly slow in Indigenous communities, particularly in remote and regional Australia. We are not making the most of the proven protective strategies available to us.

This is where many Zeroes lose me. In their efforts to promote renewed mask mandates and lockdowns, some have chosen to call vaccine efficacy into question. Given the clear evidence that full and up-to-date vaccination is highly protective against severe illness, it’s hard to imagine a more dangerous rhetorical strategy.

These Zeroes claim that vaccines don’t work because they don’t prevent infection. Yet vaccines were designed and tested for a completely different purpose — not to prevent transmission but to reduce the risk of severe illness once infection has occurred.

This doesn’t reflect a lack of ambition on the part of vaccine designers. They took this approach because the evidence shows that coronaviruses as a family can easily evade immune defences against primary infection — which is exactly what we’ve seen with the Omicron strain. The ongoing transmission of Covid-19 is evidence vaccine designers got it right.

Calling vaccine efficacy into doubt serves to stoke fear of Covid infection. In a sense, the zero-Covid debate reflects a disagreement about the pragmatic value of alarm — whether it is useful for the general public to perceive a continuing sense of crisis. This is what that second frame comes down to; it suggests that everyone should perceive themselves as being at continued risk from Covid-19. And here I would point out that alarm is not a renewable source of energy.

It’s helpful to distinguish between the end of the pandemic and the end of the crisis. Crises end when we collectively and implicitly decide they are over. As the American economist Anthony Downs’s theory of the issue-attention cycle suggests, these decisions reflect patterns in media coverage rather than trends in scientific data. The theory predicts a drop-off in attention as people acclimatise to pandemic life and, in particular, once people come to believe the problem largely affects a numeric minority.

I’ve been through this once before with a different epidemic — the HIV/AIDS crisis. In the mid 2000s many people assumed the advent of effective HIV treatments meant the crisis was over. Almost overnight, prevention practitioners went from being seen as heroes in a valiant battle to being considered failures for not preventing continuing transmission.

Covid policymakers have undergone a similar humiliation. Early in the crisis Australia picked a policy of flattening the curve, postponing the bulk of infections until the health system was prepared to cope and vaccines had become available. Although it wasn’t without significant problems, including the slow rollout of vaccines under the previous government, this strategy was for the most part a resounding success.

But the zero-Covid movement seeks to move the goalposts, redefining success as the prevention of transmission altogether. They depict a successful strategy as a failure, or worse — as “pro-infection.”

A way does exist for describing what an end to the pandemic would mean in biological and epidemiological terms. It would happen if three conditions are met:

1. A new variant causes relatively mild disease.

2. The variant is highly infectious and therefore outcompetes other variants that cause more severe illness.

3. Infection with this variant generates enough immunity to stop people from getting it again within the space of a year or so.

If these conditions were met, the experience of Covid-19 would become just like the experience of cold and flu. In effect, Covid-19 would become just another coronavirus among the many that circulate globally and locally.

Omicron meets criteria #1 and #2, but whether it meets the third criterion is still an open question. The Zeroes mobilise plenty of anecdata about people getting Covid six weeks after their last bout; but prior infection clearly does confer some degree of immunity for some time — it’s just not clear how much or how long. While we wait for more data, based on the justice claim and the epidemiology I have to conclude that Covid-19 is not yet over — but the sense of crisis has certainly passed.

We may never end the incidence of Covid-19, but we have proven our ability to reduce its impact. To succeed fully in this strategy, we must also protect groups of people who are more at risk of severe illness. We need to be clearer about which groups are actually at risk — it’s not everyone with immune deficiency or disability generally. We need scientific advances in vaccines, monoclonal antibodies, and antiviral medications, not to mention development of more sensitive rapid antigen tests. But we might also need to accept changes in our everyday way of life that are intended to reduce the risk to people we know and love. •