Covid-19 second wave could be prevented if 50% of people do this

As communities ease restrictions in an effort to reboot some semblance of normal life, over a dozen states have reported record highs of Covid-19 cases this week. This resurgence in infections could contribute to the second wave of coronavirus, experts warn.

Luckily, this boomerang effect isn't totally inevitable or out of our control. Public health experts stress there is a cheap but powerful tool in our arsenal to prevent a second wave: face masks.

According to two new comprehensive mathematical models, routine face mask use by at least half the population keeps the coronavirus reproduction number under 1.0.

This would allow for less stringent lockdown measures and flatten future disease waves: The reproductive number is the number of individuals infected by the introduction of a single infectious individual to an otherwise susceptible population. If the reproductive number is below 1.0, Covid-19 infection is theorized to slow and eventually die out.

The modeling analyses provide support for the "immediate, universal adoption of face masks by the public," the researchers write.

These findings were published Wednesday in the journal Proceedings of the Royal Society A.

Masks aren't perfect, but they are one of the most effective, practical tools to beat back Covid-19. They're especially vital in resource-strapped areas of the world, the study's authors say.

"In the developing world, where there are very few options for preventing spread, masks can be a useful tool to help slow the spread," study lead author Richard Stutt, a researcher at the University of Cambridge, tells Inverse.

Stutt and his team's sweeping projections offer a roadmap for policymakers advising the public on when and how to use face coverings most effectively.

There are no "one-size-fits-all" recommendations, as the timing of a potential second wave varies country to country, and community to community. But the research shows face masks can dramatically curb Covid-19 cases and should be used continually until an effective treatment or vaccine is available.

“If widespread face mask use by the public is combined with physical distancing and some lockdown, it may offer an acceptable way of managing the pandemic and reopening economic activity long before there is a working vaccine," Stutt says.

Masks work by physically blocking viral droplets from spreading through talking, coughing, sneezing, and singing. These sneaky droplets are the primary mode of Covid-19 transmission, so containing them is crucial to curbing the virus.

To determine exactly what level of face mask adoption is needed to manage Covid-19's spread, Stutt and his team modeled a vast array of scenarios, projecting a gradient of face mask use (from zero to total use) across the population at various stages of infection and transmission via air and surfaces.

They factored in how effective a particular type of face mask or covering would be (homemade vs store-bought vs medical grade) as well as the effect of social distancing measures. They also looked at potentially negative aspects of mask use such as increased face touching.

The results are striking: In all modeling scenarios, routine face mask use by 50 percent or more of the population effectively "flattened the disease curve," reducing spread to a reproductive number less than 1.0.

Wearing masks whenever one is in public is predicted to be twice as effective at reducing viral transmission when compared masks only worn after symptoms appear.

Even homemade masks with limited effectiveness can dramatically reduce transmission rates if worn by enough people, regardless of whether they show symptoms, the researchers report.

Importantly, masks don't give the public a green light to resume "business as usual" social interactions, Stutt explains.

"People should keep following the guidelines for social distancing as they come out of lockdown," Stutt says. "We believe that mask use will help, but the best results will be achieved when people are using masks effectively and combining this with careful social distancing."

In the models, 100 percent mask adoption combined with intermittent lockdowns prevented any further disease resurgence for 18 months — time that could prove to be crucial, while we wait for an effective vaccine.

While we wait, Stutt recommends we wear masks of "good design and well fitted" to ensure effectiveness.

Abstract: COVID-19 is characterized by an infectious pre- symptomatic period, when newly infected individuals can unwittingly infect others. We are interested in what benefits facemasks could offer as a non- pharmaceutical intervention, especially in the settings where high-technology interventions, such as contact tracing using mobile apps or rapid case detection via molecular tests, are not sustainable. Here, we report the results of two mathematical models and show that facemask use by the public could make a major contribution to reducing the impact of the COVID-19 pandemic. Our intention is to provide a simple modelling framework to examine the dynamics of COVID-19 epidemics when facemasks are worn by the public, with or without imposed ‘lock-down’ periods. Our results are illustrated for a number of plausible values for parameter ranges describing epidemiological processes and mechanistic properties of facemasks, in the absence of current measurements for these values. We show that, when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, Re, can be decreased below 1, leading to the mitigation of epidemic spread. Under certain conditions, when lock-down periods are implemented in combination with 100% facemask use, there is vastly less disease spread, secondary and tertiary waves are flattened and the epidemic is brought under control. The effect occurs even when it is assumed that facemasks are only 50% effective at capturing exhaled virus inoculum with an equal or lower efficiency on inhalation. Facemask use by the public has been suggested to be ineffective because wearers may touch their faces more often, thus increasing the probability of contracting COVID-19. For completeness, our models show that facemask adoption provides population-level benefits, even in circumstances where wearers are placed at increased risk. At the time of writing, facemask use by the public has not been recommended in many countries, but a recommendation for wearing face-coverings has just been announced for Scotland. Even if facemask use began after the start of the first lock-down period, our results show that benefits could still accrue by reducing the risk of the occurrence of further COVID-19 waves. We examine the effects of different rates of facemask adoption without lock-down periods and show that, even at lower levels of adoption, benefits accrue to the facemask wearers. These analyses may explain why some countries, where adoption of facemask use by the public is around 100%, have experienced significantly lower rates of COVID-19 spread and associated deaths. We conclude that facemask use by the public, when used in combination with physical distancing or periods of lock-down, may provide an acceptable way of managing the COVID- 19 pandemic and re-opening economic activity. These results are relevant to the developed as well as the developing world, where large numbers of people are resource poor, but fabrication of home-made, effective facemasks is possible. A key message from our analyses to aid the widespread adoption of facemasks would be: ‘my mask protects you, your mask protects me’.