This week marks five years since Trump declared a national state of emergency over the COVID outbreak

This week marks five years since March 13, 2020 , the day President Donald Trump declared a national state of emergency over the novel coronavirus outbreak.

Peter Bergen : Five years after the COVID-19 emergency was declared, has more conclusive evidence emerged one way or the other? He says the efficacy of masks alone does not settle the question of mask mandates, which is far more complex.

The BMJ published a review evaluating the role of masks and respirators in preventing respiratory infections in health care and community settings.

The British team noted the difficulty of evaluating studies conducted in the midst of an ongoing epidemic.

A Columbia University study found that individual masking behaviors limit masking efficacy in randomized controlled trials.