It seems terribly wrong that so fine a spring day should be carrying a deadly danger. The daffodils and cherry blossoms proclaim renewal and hope; the crisp, clear air seems incapable of anything so treacherous.

Yet we walk in fear. We want to scrub ourselves again and again against the invisible attacker; we wonder where to hide, how to escape. What can we give our children to protect them? Should we stock up on food and toilet paper? Can we trust the government, which seems bent on making soothing sounds and putting blame elsewhere?

It’s the spring of 1986, and I’m in Moscow with my family as The Times’s bureau chief. Since April 26, when a reactor at the Chernobyl nuclear power plant erupted and spewed radioactivity far and wide, we have been wrestling anxiously with the unknown — as reporters, trying to distinguish fact from propaganda; personally, trying to cope with a threat that rides silently and invisibly with the wind.

Today’s threat is different, of course. Radioactivity is not a pathogen. The coronavirus can spread from continent to continent as fast as a jetliner can fly and from person to person with an unguarded touch; the fallout from the burning Chernobyl plant traveled only as far as the winds would carry it, and social distancing was useless against its radiation.