Enlarge /. A mask / shield combination offers improved protection.
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One of the biggest challenges of the COVID-19 pandemic is that we just don't know what works against the SARS-CoV-2 coronavirus. Most of the scientific studies on pandemic control have focused on the influenza virus, which is different from the coronavirus in many ways. The coronaviruses we know about – SARS, MERS, and two cold viruses – are vastly different from one another.
We don't have exact data on what works. Do we need two meters of social distance or three? What types of face masks are most effective? We try to collect data on these topics as we implement them. In some good news, we now have some data indicating something that is effective: plastic face protection.
To the subcontinent!
The work was carried out in India using a public health program that began as the pandemic spread in that country. Staff at a research network in Chennai agreed to voluntarily go into isolation and then visit the families of those who tested positive for SARS-CoV-2 to explain things like quarantine, mask use, social distancing, etc.
Before we dive into what happened to these workers, let us step back to admire these people. They agreed to leave their families behind to live in hotel rooms. They were kept completely isolated from their friends and colleagues – meals were delivered to their rooms, and even their transport was a van with a steel divider installed to keep them isolated from their driver. All of her direct human contact has been with people who are likely infected. While the families they visited were asked to wear masks and stay at least three feet away from health workers, compliance was erratic.
And while they were given gloves, surgical masks, and alcohol-based hand sanitizer, it only took two weeks for the first workers to develop symptoms. The program has been suspended and all employees have been tested for the virus. Of the 62 people involved, a dozen were infected. Together they had visited 5,880 homes and came into contact with a total of 222 people who ultimately tested positive for the virus. Fortunately, the partitions in their transport worked and none of their drivers got infected.
When the program was restarted, an additional form of protection was introduced: a clear plastic face shield. The health workers were also given ethanol to clean their masks between home visits. With these measures, workers visited an additional 18,228 homes, where 2,682 people eventually tested positive for the virus.
There were no infections among health care workers.
It is entirely possible that the initial infection may have made employees more cautious about restarting the program. However, it is not clear whether behavior change could be sustained during 18,000 home visits. Thus, the face shields are likely what provided the critical difference.
The authors of the paper describing the results are unsure of what the critical contribution was. The shield could have circulated air around the face or prevented the face mask from becoming contaminated. It would also provide some protection to the eyes, which are a known route of infection. So we can learn more here. However, the results seem sufficient to suggest that those at high risk could benefit from using face shields.
JAMA, 2020. DOI: 10.1001 / jama.2020.15586 (About DOIs).