No strong rationale for face shields

As public health practitioners, we support the government’s efforts to encourage public health protocols like mask-wearing, just as we endorse the slow — but improving — vaccination campaign. However, we must speak out against the IATF’s insistence on face shields in all settings. Indeed, leaving aside the curious fact that we’re the only country with this policy, we believe there is no strong rationale for it.

“Rationale” is not just about blindly accepting expert opinion or overconfidence in one or two papers. Every paper, regardless of where it is published, requires thoughtful consideration in terms of how evidence is applied in different contexts and how potential benefits can be weighed against harms and risks, especially for something as far-reaching as a universal mandate.

Based on the above, the IATF and its health experts have failed in meeting their own standard of “science-based policies.”

The two papers they frequently cite offer weak evidence. The first one, Chu et al. (2020), suggests that eye protection may offer some benefit in preventing COVID-19 on the basis of a systematic review and meta-analysis. A closer look at the studies included in the review show equivocal results, and most of them involved health care settings during past outbreaks that did not consider the possibility of airborne transmission. The paper also does not consider the joint effects of mask-wearing and eye protection, and the IATF’s experts have incorrectly multiplied their individual efficacies from the paper as if the impact of mask-wearing is completely distinct from the impact of eye protection.

Superficially, the results of the second one, Bhaksar and Arun (2020), seem compelling: Before wearing face shields, 12 out of 62 health workers contracted COVID-19, but after wearing face shields, the rest did not get infected. The IATF’s experts have mistakenly assumed this exploratory evidence from a methodologically weak before-after study design as conclusive findings from a randomized trial. This paper at best supports recommending face shields in health care contexts, but not requiring them universally, and certainly not outdoors.

Of course, stronger evidence may emerge to support the benefit of face shields, but just because there’s benefit for something in some settings doesn’t mean it should be required in all contexts. Following this logic, we should also ban cars in cities (because Chen et al. 2020 says air quality is a determinant of COVID-19 survival) and require people to go vegan (because Kim et al. 2020 says it decreases likelihood of moderate-to-severe COVID-19).

To be fair to the IATF’s health experts, we don’t think they are acting out of political or economic self-interest, and we find the ad hominem attacks unacceptable. Indeed, we think they genuinely believe that face shields work and that, in any case, “there’s nothing to lose” with this extra layer of protection, especially with the rise of the Delta variant.

But we strongly disagree that there’s nothing to lose.

First, we risk environmental damage, with millions of face shields that will take 500 years to decompose. Already, our country is wallowing in plastic waste, and this has only been exacerbated by the pandemic. Will the IATF take responsibility for this environmental impact?

Second, we subject Filipinos to unnecessary cost, inconvenience, and in some cases, even abuse of law enforcement, as in the case of the poor doctor arrested for cycling without a face shield.

Thirdly, face shields detract attention from measures that actually work. If, as the IATF experts acknowledge, the problem is we can’t control ventilation, shouldn’t we be trying to solve it instead of enacting measures with little basis? Addressing the pandemic requires structural policies that minimize community transmission and encourage healthier behaviors, rather than force individual responsibility on people despite unaddressed structural challenges.

Finally, the insistence on face shields undermines the credibility of public health expertise in general. We want our people to trust public health, but we risk compromising even our credibility on other important matters like vaccination if we insist on something as indefensible as a universal face shield mandate.

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Jason Haw is an instructor at the Ateneo de Manila University currently completing his Ph.D. in epidemiology at the Johns Hopkins Bloomberg School of Public Health. Gideon Lasco is a physician, medical anthropologist, and Inquirer columnist.