The Vietnamese study found that cloth masks increased risk compared to medical masks, not compared to no mask. Confusingly, their control group also wore masks,

The Vietnamese study found that cloth masks increased risk compared to medical masks, not compared to no mask. Confusingly, their control group also wore masks, just in fewer situations: > Hospital wards were randomised to: medical masks, cloth masks or a control group (usual practice, which included mask wearing). The first paper doesn't say what kind of mask the control participants wore, but a subsequent paper says only 38/458 control participants wore a cloth mask. I think the implication is that the rest wore medical masks, though neither paper ever says explicitly. https://bmjopen.bmj.com/content/10/9/e042045 https://bmjopen.bmj.com/content/10/9/e042045 That subsequent paper is a subgroup analysis that should be treated with some care, but found comparable performance between medical masks and cloth masks washed in the hospital laundry. That suggests the problem was inadequate hand-washing, not the masks themselves. There is zero evidence that masks increase incidence of disease compared to no mask. RCTs of mask use in public (e.g., DANMASK-19 and earlier flu studies) suggest that the benefit of the mask to the wearer--excluding the benefit of the mask to others nearby from source control--is less than a 50% reduction in disease, with a 95% confidence interval centered somewhere around 20% but including zero. The RCT evidence says nothing beyond that. Public health authorities have indeed spoken with unjustified confidence as to the efficacy of masks. You're doing the same thing here in the opposite direction, though. Given the information above, can you correct your comment?