Covid vaccines: coverage, side effects, second dose. The differences

First dose of anti-Covid vaccine and second: but after how much? Total or partial coverage of the infection: in how long? Symptomatic, and not, struggling with the injection: right to give it to both? And how can they react? Giovanni Maga, virologist, director of the Cnr of Pavia, sheds light on a series of questions that four anti-Covid vaccines with different times and effects are multiplying in the minds of Italians.