Viruses that were on hiatus during Covid are back — and behaving in unexpected ways

For nearly two years, as the Covid pandemic disrupted life around the globe, other infectious diseases were in retreat. Now, as the world rapidly dismantles the measures put in place to slow spread of Covid, the viral and bacterial nuisances that were on hiatus are returning — and behaving in unexpected ways. Consider what we’ve been seeing of late. The past two winters were among the mildest influenza seasons on record, but flu hospitalizations have picked up in the last few weeks — in May! Adenovirus type 41, previously thought to cause fairly innocuous bouts of gastrointestinal illness, may be triggering severe hepatitis in healthy young children. Respiratory syncytial virus, or RSV, a bug that normally causes disease in the winter, touched off large outbreaks of illness in kids last summer and in the early fall in the United States and Europe. And now monkeypox, a virus generally only found in West and Central...