I see no simple solutions or guarantees in this scenario. This includes all of the existing "vaccines" being distributed, apart from policies like wearing masks and social distancing.
That said, the use of masks is just another aspect of loss control. Policy intended to
avoid and/or reduce hazards and casualties through proactive measures. A concept that is neither fool-proof or carries any kind of guarantee. It's just another precautionary measure recognizing there are no absolutes over who or how one contracts- or avoids this virus no different than the medical community's emphasis on preventative care.
A mask won't prevent particles from escaping, but they may prevent them from being aerosolized at a great distance which can potentially infect that may more people. Again, there are no absolutes in such equations. Such policies which are designed to reduce hazards and casualties- not eliminate them entirely.
Though none of this really addresses the phenomena of morale hazards. Humans who choose or advocate to do nothing to protect themselves or others in society. While insurers can find creative ways of dropping them as policyholders, it's a bit more difficult for the authorities. It potentially represents an obstacle in attaining herd immunity, which also has no guarantee.
Infectious disease physician breaks down coronavirus mask myths