Why did Japan’s fifth and biggest wave of the coronavirus pandemic, driven by the supercontagious delta variant, suddenly come to an abrupt end following a seemingly relentless rise in new infections?

A certain mutation in the COVID-19 Delta variant causes infected cells to form disruptive chunks in the lungs and leads to more serious symptoms of the disease, a research team said. If the cells in ...

The Delta coronavirus mutant strain is seen in this electron microscope photo provided by the National Institute of Infectious Diseases. The Mainichi Shimbun answers some common questions readers may ...