Could masks curtail the post-lockdown resurgence of COVID-19 in the US?

The community lockdown measures implemented in the United States, during late March to end of May of 2020, resulted in a significant reduction in the community transmission of the COVID-19 pandemic throughout the country. However, a number of US states are currently experiencing an alarming post-lockdown resurgence of the pandemic, triggering the fear for a possible severe second wave of the pandemic in some US jurisdictions. We designed a mathematical model for addressing the key question of whether or not the universal use of face masks can halt or curtail such resurgence (and possibly avert a second wave, without having to undergo another cycle of major community lockdown) in the states of Arizona, Florida, New York and the entire US. The model was parametrized and fitted using cumulative mortality data from the four jurisdictions. Our study highlights the importance of early implementation of the community lockdown measures. In particular, a sizable reduction in the burden of the pandemic would have been recorded in each of the four jurisdictions if the community lockdown measures were implemented a week or two earlier. These reductions are greatly augmented if the early implementation of the lockdown measures is complemented with a public face masks use strategy. It is shown that the pandemic would have been almost completely suppressed from significantly taking off if the lockdown measures were implemented two weeks earlier, and if a sizable percentage of the residents of the four jurisdictions wore face masks during the respective lockdown periods. If the level of lifting of community lockdown is high (which entails allowing for greater community contacts and re-opening of businesses and social activities, in comparison to what was allowed during the community lockdown period), the states of Arizona and Florida will record a devastating second wave of the pandemic by the end of 2020, while the state of New York and the entire US will record milder second waves. If the level of lifting for the community lockdown was mild (i.e., only allowing very limited community contacts and business activities, in comparison to the lockdown period), only the state of Florida will experience a second wave. The severity of the projected second wave depends on the level of lifting of the community lockdown. For instance, the projected second wave for Arizona and Florida, associated with moderate and high level of lifting of lockdown, will be more severe than their respective first wave. For high level of lifting of lockdown measures, the increased use of face masks after the lockdown period greatly reduces the burden of the pandemic. In particular, for this high lifting scenario, none of the four jurisdictions will experience a second wave if half of their residents wear face masks consistently after their respective lockdown period). A testing strategy that increases the maximum detection rate of asymptomatic infected individuals (followed by contact tracing and self-isolation of the detected cases) greatly reduces the burden of the pandemic in all four jurisdictions, particularly if also combined with universal face mask use strategy. Universal use of face masks in public, with at least moderate level of compliance, could halt the post-lockdown resurgence of COVID-19, in addition to averting the potential for (or severity of) a second wave of the pandemic in each of the four jurisdictions.