A: YES! As the Nerdy Girls like to reiterate, risk reduction is not all or nothing.
While masks have been encouraged as “source control”- a way of blocking outbound aerosols and droplets as you breathe, speak, sneeze or cough, accumulating evidence suggests that they can provide important protection to the wearer as well.
See our May 2nd post for a refresher on “ingress vs. egress”.
“The good news is that preventing transmission to others through egress is relatively easy.”
“It’s like stopping gushing water from a hose right at the source, by turning off the faucet, compared with the difficulty of trying to catch all the drops of water after we’ve pointed the hose up and they’ve flown everywhere.”
The idea of wearing a mask to protect others has been particularly important in the context of what seems to be a high level of contagiousness prior to the onset of symptoms.
While inbound airborne particles may more easily float around small gaps in a mask, the mask still provides an important barrier that can block virus particles and protect the wearer.
In a recent paper, Dr. Monica Ghandi and colleagues argue that even with imperfect protection, wearing a mask can REDUCE THE INFECTIOUS DOSE of SARS-CoV-2 in the case of exposure, leading to milder or asymptomatic illness.
This hypothesis is consistent with animal evidence from earlier this year from hamsters—yes, “masked” hamsters!
Well sort of….
Researchers housed coronavirus-infected and healthy animals in adjoining cages, creating buffers made of surgical masks for some cages. Many of the healthy hamsters behind the partitions never got infected, and those who did got less sick than their “maskless” neighbors.
While science will continue to further test these hypotheses and inform our prevention best practices, be assured that even imperfect prevention measures, broadly adapted, can have a BIG impact on slowing this pandemic.
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