Will Zika fears cause a population gap?

Will Zika fears cause a population gap?

Imagine a full year, or two, during which a nation’s old people die but no new people are born. Picture an elementary school with empty first- and second-grade classrooms. Look further ahead to the years no new workers join the labor pool.

How would a two-year collapse in the birth rate rattle a nation? We might be about to find out.

The immediate worries about Zika virus— which the Centers for Disease Control and Prevention has determined can cause microcephaly and other brain damage in newborn babies — are obviously medical in nature. Where should pregnant women not travel? How quickly can a vaccine be developed? At the same time, in an attempt to stave off...