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Masks have been on our minds, as health care workers, since the pandemic started. First, we were short on surgical masks, so friends and family made us cloth masks, which we knew were less effective but it was better than nothing. As the COVID threat neared, the N95 mask shortage became a more pressing issue. Three months into the battle and despite all the positive news to the contrary, we are still short and even checking on Amazon for N95 masks.

As the summer migration to Maine commences, health care workers are worried about a different kind of mask problem — the lack of “universal public masking.”

[Our COVID-19 tracker contains the most recent information on Maine cases by county]

When the state reopens, as it should, so that people can put food on the table for their families, silent coronavirus transmission in the community will increase. We should expect this increase in virus transmission to trickle into healthcare facilities.

The vast majority of people are healthy and will likely carry the virus without even knowing, but 15 percent will not be so lucky. These unlucky few are not only the elderly and immunocompromised; the coronavirus has proven capable of causing serious illness even in the healthy and young. Having said that, our nursing home population is uniquely vulnerable as many medically compromised individuals are living in close proximity. This environment is conducive to fast spread and a large number of casualties.

Nursing homes and assisted living facilities have been under lockdown for months, yet they keep falling like dominos as the community spread of the virus increases. The main vector for the virus has been the same people who are working hard to protect the elderly, our staff.

Health care workers who risk their lives to help the elders are now having to live with the guilt that they are the gate the virus uses to get to their residents and patients. That’s why the vast majority of them are highly motivated to wear masks in public when they are off duty. They carry their mask with them even when they go for a jog, in case they stop to talk to someone. They wear their masks as they walk the streets and anywhere else where there are others in close proximity. Their masks are now an important accessory, a first line of defense, for their patients.

The paradox is that the true purpose of the mask is not to protect the person wearing it, it is to protect others in case the wearer is a silent carrier of the virus. If we knew who the silent carriers were, we would ask them to wear a mask, but since we don’t know who they are, we must ask all to wear a mask until the vaccine arrives.

Wearing a mask is an act of courtesy to protect others from oneself for the possibility of having a silent infection. If others do the same in return, then the vast majority of people will be protected, just like with vaccination. The reason most of us vaccinate is so that we won’t carry the disease and pass it on to others who may not be blessed with good health and a strong immune system.

There is no scientific excuse for not taking this patriotic action of mask wearing to help reduce casualties in the COVID war, but that hasn’t stopped some from making flimsy rationalizations, like how masks may cause CO2 retention. To this we can say that a mask is not a plastic bag. We can also point at the example of surgeons who spend much of their lives wearing masks and still have functioning brains despite it.

To those of you who are eager to find ways to help the healthcare workers in this COVID war, we say: “A mask is all we ask!”

Jabbar Fazeli is a geriatrician in southern Maine.