New study: Lockdowns didn't stop the spread of COVID-19 after all

As always, approach all stories that headline the word “study” with some caution. Newsweek’s report on a new study from Stanford published this week in the European Journal of Clinical Investigation should carry the same caveat — one study does not a scientific foundation make. However, the findings in this study of the impact of lockdowns on COVID-19 transmission do seem to fit our own observations, especially in the pandemic’s second and third waves:

The most restrictive non‐pharmaceutical interventions (NPIs) for controlling the spread of COVID‐19 are mandatory stay‐at‐home and business closures. Given the consequences of these policies, it is important to assess their effects. We evaluate the effects on epidemic case growth of more restrictive NPIs (mrNPIs), above and beyond those of less restrictive NPIs (lrNPIs).

We first estimate COVID‐19 case growth in relation to any NPI implementation in subnational regions of 10 countries: England, France, Germany, Iran, Italy, Netherlands, Spain, South Korea, Sweden, and the US. Using first‐difference models with fixed effects, we isolate the effects of mrNPIs by subtracting the combined effects of lrNPIs and epidemic dynamics from all NPIs. We use case growth in Sweden and South Korea, two countries that did not implement mandatory stay‐at‐home and business closures, as comparison countries for the other 8 countries (16 total comparisons).

Implementing any NPIs was associated with significant reductions in case growth in 9 out of 10 study countries, including South Korea and Sweden that implemented only lrNPIs (Spain had a non‐significant effect). After subtracting the epidemic and lrNPI effects, we find no clear, significant beneficial effect of mrNPIs on case growth in any country. In France, e.g., the effect of mrNPIs was +7% (95CI ‐5%‐19%) when compared with Sweden, and +13% (‐12%‐38%) when compared with South Korea (positive means pro‐contagion). The 95% confidence intervals excluded 30% declines in all 16 comparisons and 15% declines in 11/16 comparisons.

In other words, despite the wide variance in types of social interventions, the harsher lockdowns provided no significant improvement in reducing community transmission than did the softer interventions did — social distancing, mask-wearing, and perhaps capacity restrictions. Their conclusion — the cost/benefit ratio for harsh interventions doesn’t justify them:

While small benefits cannot be excluded, we do not find significant benefits on case growth of more restrictive NPIs. Similar reductions in case growth may be achievable with less restrictive interventions.

On one hand, this seems counter-intuitive. How could forcing people to remain at home not slow the transmission rate of a viral pandemic? That’s precisely the logic that led to the lockdowns in the first place. And the answer might be that people didn’t just stay home. Once local and state governments closed all but the “essential” businesses, those businesses might have ended up with more traffic than usual. People also used that time to visit each other in unstructured ways, whereas keeping businesses and social-engagement venues open with better ventilation and structure might have been more wise.

After all, if the necessity is to keep people six feet apart to prevent the spread, there’s no upside to keeping them sixty feet apart, or six miles apart. Lockdowns might have forced the social impulse to get channeled in more dangerous ways than otherwise would have happened.

On the other hand, this does seem to match up with our practical experience. The states with the most draconian lockdowns appear to also have the highest community-transmission spread in recent weeks. California comes to mind especially, where hospitals are at or over capacity, but it applies to New York and a handful of other states, too. Cases are increasing in places like Florida as well but on a much lower amplitude, and it’s at least arguable that the difference could be due to Florida’s allowance for more public social interaction with proper safeguards.

The most recent wave of infections might offer some support in either direction. Did the big spike in travel for the holidays generate massively wider transmission? Or was it the mix of households that did it? Or both?

And on yet another hand (a third hand?), as Newsweek notes, other studies have shown the opposite:

Though this study’s approach did not determine any significant benefits to implementing mandatory lockdowns, others have shown that lockdowns have saved millions of lives.

A study published by researchers at Imperial College London in June found that some 3.1 million deaths had been averted due to lockdowns across Europe early on in the pandemic, Reuters reported. Additional research found that 530 million coronavirus infections had been avoided due to early lockdowns in China, South Korea, Italy, Iran, France and the United States, according to the news outlet.

This Stanford study has undergone peer review and is published in its raw form, so it’s a substantive addition to the scientific debate. Unfortunately, this debate will go on for years, even while we are having to form public policy in the moment. The faster we can roll out the vaccines, the quicker this debate gets quarantined to Academia. Vaccination policy is now far more important to social and economic health, and the public sector has to start acting like it.