A group of 300 Chinese intensive-care doctors began to arrive in Italy on Wednesday, one of several Chinese offers to support epidemic-stricken European countries, as China tries to rebrand itself internationally from source of the new coronavirus to a friendly helper.

China’s European relief efforts, while welcome, are small compared with European health-care needs. One temporary hospital in Milan alone will need 500 doctors and about 1,400 nurses for 400 intensive-care beds. But China’s initiatives have been accompanied...