Common infections may trigger lasting health problems, studies suggest

• Researchers have long believed that simple infections can lead to long-term problems.
• But solid scientific evidence has only accumulated in the last few years, experts say.
• Understanding how the immune system overreacts and strengthens may lead to better treatments.

In most people, norovirus causes miserable days in the bathroom and is quickly forgotten afterward. And many shrug their shoulders at her COVID-19.

However, a growing body of research suggests that in the unfortunate minority of patients, the immune system overreacts to these seemingly trivial insults, leaving symptoms for years or even a lifetime.