Do Face Masks Reduce COVID-19 Spread in Bangladesh? Are the Abaluck et al. Results Reliable?

Here, I review the methods and results of that study by Abaluck et al. (2021) published as a working paper by Innovations for Poverty Action (IPA): “The Impact of Community Masking on COVID-19: A Cluster-Randomized Trial in Bangladesh”, 01 September 2021.

Summary

The cluster-randomized trial study of Abaluck et al. (2021) is fatally flawed, and therefore of no value for informing public health policy, for two main reasons:

I.                    The antibody detection was performed using a single commercial FDA emergency-use-authorized (EUA) serology test that is not suitable for the intended application to SARS-CoV-2 in Bangladesh (not calibrated or validated for populations in Bangladesh; undetermined cross-reactivity against broad-array IgM antibodies, malaria, influenza, etc.). 

II.                  The participants (individual level, family level, village level) in the control and treatment arms were systematically handled in palpably different ways that are linked to factors established to be strongly associated to infection and severity with viral respiratory diseases, in particular, and to individual health in general.

These disjunctive fatal flaws are explained below. Either one is sufficient to invalidate the results and conclusions of Abaluck et al.

Furthermore, the Abaluck et al. symptomatic seroprevalence (SSP) results are prima facie statistically untenable. The treatment-to-control differences in numbers of symptomatic seropositive individuals are too small to rule out large unknown co-factor, baseline heterogeneity, and study-design bias effects. In addition, they are at best borderline significant, in terms of purely ideal-statistical estimations of uncertainty. Finally, the practice of using whole households while reporting on an individual basis, introduces unknown correlations/ clustering, and vitiates the mathematic assumptions that underlie the statistical method.