While two Sentinel readers were correct in finding the flaw (case/death “growth rates” not numbers) in Gwynneth Kelley’s assessment of the CDC study (“What if masks only protect us by 2 percent?” March 22), we should exercise more critical thinking about such poorly-designed studies.

1. Though the CDC study (https://bit.ly/3u6Qiym) claims a March-December timeline, in reality almost all US restaurants reopened in May, meaning the “100 days” studied would have extended into July/August. In May, daily new cases/deaths fell slightly nationwide, then began to rise, then plateaued. Surprise: this same progression was found in the study.

2. The study did not account for the natural progression of the virus from northern to southern latitudes. States continuing restaurant closures were mostly in the north, well after the curve had bottomed out, which completely biases the CDC data.

3. Case counts have been notoriously unreliable as PCR cycle thresholds used by most states led to a rash of false positives. The WHO took until in December to admit this (https://bit.ly/3mzo1xZ).

4. The study does not control for:

a) Any of the known drivers of COVID-19: population density, age, comorbidities, Vitamin D deficiency, particulate pollution levels, etc.;

b) The large variations in mask-wearing norms or compliance rates;

c) The effect of lockdowns, where cases and deaths are not avoided but simply postponed.

Even The New York Times noted, “the study does not prove cause and effect” (https://bit.ly/3cIuByQ).

On May 20, 2020, the CDC published a study of all the evidence around mask-wearing for flu (similar size/transmission as SARS-CoV-2) and found no support for mask-wearing for healthy people in community settings (https://bit.ly/3217dX6). Two large studies show that the widespread claim of asymptomatic spreaders is weak to non-existent (https://bit.ly/3rUxXDG, https://go.nature.com/37cZgRw). On 6/5/20, the WHO announced it had no direct evidence that masking healthy people prevents SARS-CoV-2 infection (https://bit.ly/3wKV9rg). On 12/1/20, the WHO admitted there was “limited and inconsistent evidence for masking” (https://bit.ly/3mwzHS5). Other studies claiming mask effectiveness have been widely panned for their poor design and biased conclusions.

Denmark ran the only large randomized control trial of SARS-COV-2 and masking (https://bit.ly/39AHrNp), finding no statistically significant advantage for mask-wearers. State and county-level comparisons confirm this (https://bit.ly/2ZfVgvc). OSHA experts agree plus warn of numerous harms (https://youtu.be/IX3UeyBCaSk).

Common sense should tell us if masks worked as was proclaimed all last year, they wouldn’t now be recommending we wear two or three. It’s time people consider the political motivations behind the never-ending mandates.