One of the biggest challenges of the COVID-19 pandemic is that we just do not know what works against the SARS-CoV-2 coronavirus. Most of the scientific studies on pandemic control are focused on the flu virus, which in many ways differs from the coronavirus. The coronaviruses we know something about – SARS, MERS, and two cold viruses – are very different from each other.
We are sitting without hard data on what works. Do we need two meters social distance if three? What types of face masks are most effective? At the same time, we try to gather data on these issues so that we can implement them. So in a little bit of good news, we now have some data that indicates what is effective: plastic face shields.
To the subcontinent!
The work was done in India and takes advantage of a public health program, initiated as the pandemic spreads through that country. Employers at a research network in Chennai voluntarily voted to go into isolation, then try with the families of those who test positive for SARS-CoV-2 to explain things like quarantine, mask use, social distance and so on.
Before we get into what happened to these workers, we need to step back to admire these people. They decided to leave their families behind to live in hotel rooms. They were kept completely isolated from their friends and peers – food was provided in their rooms, and even their transport was a van with a steel divider installed to keep them isolated from their driver. All their direct contact with people was with people who were probably infected. While the families they visited were asked to wear masks and stay at least six feet away from health workers, compliance was unfair.
And although they received gloves, surgical masks and sanitizer for alcohol, it took only two weeks for the first workers to develop symptoms. The program was shut down, and all workers were screened for the virus. Of the 62 involved, a dozen were infected. Collectively, they had visited 5,880 homes and came in contact with a total of 222 people who eventually tested positive for the virus. Fortunately, the parties worked in their transport, and not one of their drivers got infected.
Restart
When the program was restarted, an additional form of protection was put in place: a clear plastic face shield. The health workers also received ethanol to clean their masks between home visits. With those measures in place, workers visited an additional 18,228 homes, in which 2,682 people eventually tested positive for the virus.
There were zero infections among the health care workers.
It is quite possible that the initial infection increases the sense of caution that the workers took when restarting the program. But it is not clear whether any behavioral changes could be maintained in the course of 18,000 home visits. Thus, the face screens are probably what provided the critical difference.
The authors of the paper describing the results are not sure what the critical contribution was. The shield could have drained air around the face if it prevented the face mask from being contaminated. It would also provide some protection for the eyes, which are a known route of infection. That there are even more we could learn here. But the results seem to be enough to indicate that individuals at high risk could benefit from the use of face shields.
JAMA, 2020. DOI: 10.1001 / jama.2020.15586 (About DOIs).
