How will the pandemic end?

Elimination. Border incursions. An outbreak. A lockdown, which takes us back to elimination. Rinse and repeat for two or more years, until the whole population receives a proven safe and effective vaccine. That’s the pessimist’s view of the near future for New Zealand.

Contrast that with the optimist’s view. A less porous border meaning fewer outbreaks. Better targeted lockdowns, with less social and economic disruption. And (hopefully) the earlier availability of a vaccine. 

There is actually little difference between these two views. Both are similarly bleak. I think they are missing something important. To illustrate, let me tell you about my experience of getting off the couch. 

An inconvenient truth

“You’re getting too cuddly. You need more exercise.” Something small can lead to big changes in one’s life – in this case it was an unwelcome comment from my partner about my couch potato lifestyle and body shape. This wasn’t new information (the scales hadn’t been lying to me) but I did take notice. I took up running, built up to 5km; kept at it, and finished about halfway through the field of a half-marathon. And, just a couple of years after that, I found myself at the start line for my first ultra-marathon (80km) trail-running race: the 2005 Cradle Mountain Run.

The trail run went unexpectedly well

“Well” meant I finished. Alive and sore but not broken. And “unexpectedly” meant a more-than-respectable time of 9 hours 57 minutes, and equal 5^th place. A perfect opportunity to retire on a high and retreat to the couch. But my innate persistence (or a deep-seated personality disorder – take your pick) led me back to the start line the next February, and almost every year since.

Naturally (or is that unnaturally?) I wanted to improve my time. I was inexperienced, so there was lots of scope to improve. And many sources of potential improvement: knowledge, gear, nutrition, hydration, pacing, training and mental attitude. At different times I held great hopes of finding and cracking one of these, leading to a surge in speed, endurance, comfort and, of course, a better placing. But while the single magic sauce proved elusive, my times kept improving year-on-year. By 2011, I managed 8 hours 45 minutes and 2^nd place. The following year squeezed off a further 30 seconds, this time for 1^st place.

It is not clear to me what I’d actually done to improve. The reality, I think, was a little improvement on every item on my list. Nor was it clear when I crossed the line from cuddly couch potato to endurance athlete.

Knowledge, technology and learning-by-doing

I attribute my running improvement to knowledge, technology and learning-by-doing. Collectively, these things allowed me to steadily, incrementally improve my performance. And, “magic sauce” vaccines aside, it’s these factors that I think are missing from the views of both pessimist and optimist on COVID-19.

Here’s my list of potential improvements in our collective ability to deal with the pandemic over time. 

1. Better treatment of COVID-19, reducing the severity of the disease. This would be visible as reduced hospitalisation rates, shorter hospital stays and lower case-fatality rates. (The recent news on remdesivir and dexamethasone is promising.)
2. More effective PPE and infection-control processes in high-risk environments (eg, hospitals, nursing homes, planes, quarantine facilities).
3. Better (ie, risk-adjusted, less costly, more effective) public health interventions.
4. Improved tests for active infections (ie, lower false negatives).
5. Improved tests for immunity (ie, lower false positives).
6. Better border control and quarantine (including risk-adjusted targeting).
7. Improved contact tracing (ie, lower cost, more comprehensive, increased compliance).
8. Emerging herd immunity (in the hardest hit places and populations).
9. A likely (though by no means guaranteed) reduction in the virulence of the virus.¹
10.  Early vaccines (partially effective or deployed with limited coverage).

Not with a bang, but a whimper

There is a real possibility that the pandemic will fizzle out over time because the combined effect of multiple improvements, each insufficient to deliver a killer blow. Not all of the improvements in my list would be necessary; nor do any of them need to be perfect.

If treatments improved so that COVID-19 was no more lethal than influenza, then a regular health system response may be more appropriate than a pandemic one. With improved testing technology, effective border control and quarantine measures would be less crucial. Better isolation of those in high risk environments would support differentiated rather than universal social distancing, which could reduce infections and enable less strict lockdowns for lower-risk groups. Improved contact tracing would reduce both the likelihood and extent of any outbreaks, and support the narrower targeting of policy measures including lockdowns. And even an imperfect vaccine could lower the likelihood of catching the disease, or moderate its severity.

Such improvements, supported by a careful, well-informed mix of policy measures, should be able to keep the reproduction number of COVID-19 below 1, allowing the pandemic to slowly fizzle out.² The task of finding such a mix should get easier over time. We are seeing unprecedented efforts across the world to pursue knowledge, technology and learning-by-doing, and as they advance the problem gets easier, one small step at a time.

When and how?

People, myself included, are attracted to concrete stories. X precedes Y. A causes B. When C arrives, D will closely follow.

That makes it hard to argue a case for my fizzle out scenario. I cannot say which of these improvements will happen, when they will happen, or by how much they need to improve to make a difference.

The world is complex. Economists along with other social scientists typically use a very useful assumption: ceteris paribus or “other things equal”. This assumption is a very powerful tool in understanding how the world works. Looking backwards, it allows a researcher to isolate a single factor and understand its effects on outcomes of interest. Looking forwards, it allows researchers to confidently make predictions with a standard caveat: “as long as nothing else changes”.

For all of us, it is mentally easier to hold almost everything constant, and make success conditional on a single big fix with a direct causal effect. A vaccine is the big fix in both the pessimists’ and optimists’ view. But as my running story illustrates, you can win without a big fix.

Pandemics invite wartime analogies. Hunkering down, personal privations and death tolls closely fit those analogies. However, there is nothing that requires a pandemic to end with a clear victory and a ticker-tape parade. Taking the wartime analogy in a different direction, war is a great spur for technological improvement. The SARS-Cov-2 virus got an early lead, but the humans are closing quickly.

My take outs

• Difficult situations are sometimes resolved without a decisive victory attributable to a single, clearly defined cause.
• Small improvements on many fronts are likely in the “war” against COVID-19. No single improvement may be decisive, but the combined effect of these improvements may tip the balance.
• A repeating cycle of outbreaks and lockdowns broken only by a vaccine is not inevitable. There is a very real possibility the pandemic will fizzle out. This will happen in different places at different times, without a clear date or cause.

Notes
1. Evolution pushes pathogens towards being less virulent over time (at least until selection effects increase the host populations’ resistance), because live healthy hosts are better (on average) at spreading the pathogen than sick or dead ones.
2. We now know that not-so-careful mixes of high- and low-cost policy measures can lower the reproduction number below 1, and keep it that way. (That is, of course, conditional on the country having a functional government). Control is possible but expensive using the mixes of policy measures adopted to date. Costs can (and likely will) fall as countries learn from their own and others’ experience.

Photos
From cradlemtnrun.asn.au