How careful is too careful after a second COVID-19 vaccine?

In days of yore, when someone told me to “be careful,” what I should do next was crystalclear.

I should stop in my tracks before I stepped in front of the car that I had not seen coming. I should tighten my grip on the sharp knife I had been handling too casually. I should quit making disparaging remarks about the medical profession when one of my dining companions was a noted physician.

In March of 2021, the exhortation to “be careful” is about to lose its clarity.

After my second Pfizer shot takes hold, when someone tells me to “be careful,” I will be forced to respond, “I have no idea what you mean by that.”

For a full year, I have been the walking definition of carefulness and caution. I have resolutely kept my distance from sources of possible infection, even though this has meant shunning the company of the complex organisms that I had habitually designated as “my friends.” My only form of incorrigible risk-taking has been going to grocery stores, where the other shoppers and I have been equals in our reclusive, introverted, and antisocial behavior.

But soon, when I am fully vaccinated, “be very careful” will begin to evolve into “be a little less careful.”

What will that mean? Unquestionably, a vaccine with 95% effectiveness offers a degree of liberation from worry and anxiety. And yet important questions set limits to that liberation. How long does the vaccine work? How will I know when the duration of its effectiveness begins to peter out?

Even more unsettling is the recognition that a vaccinated person, even while suffering no symptoms herself, might still be capable of spreading the virus to others. So, if I were to make a merry return to restaurant-dining, my proximity could mean a steep decline in merriment for the people at tables near mine, in the days that followed.

Now for the riddle that no expert can solve for me: of the innumerable changes that I have made in my conduct, and the countless restrictions that I have put on my activities, which of those changes and restrictions did the trick and protected me from infection?

Wouldn’t it be great if I could keep practicing the changes that kept me safe while loosening up on the constraints that never made much difference anyway?

And wouldn’t it be even greater if I could tell which was which?

For human beings, calibrating what it means to “be careful” is an enterprise in decision-making that we perform in a swirl of subjectivity, as fear and complacency, trust and suspicion, dread and confidence, compete for our allegiance.

If we can trust Mark Twain (and, a good share of the time, we can!), cats have a significant advantage over human beings when it comes to figuring out how to

“be careful.”

“If a cat sits on a hot stove,” Twain said, “that cat won’t sit on a hot stove again. But that cat won’t sit on a cold stove either.”

The experienced cat knows that stoves can be trouble and therefore chooses not to venture into an experiment that could go badly.

For the short term, I am OK with the feline level of wisdom.

Sometime around mid-May, I plan to upgrade to the human.