black lives matter protest
There was much consternation over political mass gatherings during the pandemic. When President Trump began holding campaign rallies in June of 2020, health officials described the move as "extraordinarily dangerous".

Around the same time, a group of 1,000 public health 'experts' signed a letter calling for authorities to let Black Lives Matter protests go ahead - on the grounds that "white supremacy" is a "lethal public health issue". As one epidemiologist put it: "In this moment the public health risks of not protesting to demand an end to systemic racism greatly exceed the harms of the virus." Okay...

Those who supported the Black Lives Matter protests were in turn accused of hypocrisy by conservatives - given that only a few months before they'd been calling for lockdowns and bans on mass gatherings.

A new paper, published in the prestigious journal Nature Human Behaviour, suggests that all this consternation was misplaced (well maybe not the accusations of hypocrisy, but the rest of it). Eric Feltham and colleagues studied political mass gatherings in the United States, and found that they had no impact on the course of the epidemic.

While many papers have studied political mass gatherings, this one looks to be more rigorous than most. The researchers examined "essentially all" such gatherings that took place in 2020-21 (including Trump's campaign rallies and the Black Lives Matter protests) at the level of US counties. They focussed on daily deaths as an outcome measure, due to the shortcomings of cases data.

And they carefully matched each county where a gathering took place to a 'control' county that was similar in other relevant respects. In particular, they matched counties not only on socio-demographic characteristics, but also on the cumulative death rate up to the point where the gathering took place - thereby adjusting to a large extent for the size of the susceptible population (an inverse correlate of the cumulative death rate).

As noted, there was no evidence that political mass gatherings affected the course of the epidemic. This was true for all the types of gatherings they looked at, and for alternative outcome measures like daily cases.

As to why they had no effect, Feltham and colleagues speculate that it may be because attendees spent much of the time outside and/or engaged in social distancing, and because they were usually required to wear masks. Needless to say, I do not find the second of these suggestions very plausible. (And note: even the mass gatherings that involved indoor voting had no effect.)

The paper's findings would seem to have quite far-reaching implications: if even mass gatherings don't affect the spread of the virus, it seems difficult to believe that Western lockdowns had much of an impact. Indeed, the findings are consistent with a model where the course of the pandemic is determined by factors like population structure, with 'NPIs' making little or no difference.

Interestingly, the researchers themselves avoid this conclusion, noting that their null result "stands in contrast to the sizeable effects estimated for some other non-pharmaceutical interventions". Make of that what you will.