Why is my calendar full of virus warnings or strange events?

Reviewed answer

These are often unwanted invitations or calendar subscriptions, not a virus diagnosis.

Do not open links or call numbers inside the events.
On iPhone, open Calendar, tap Calendars, and inspect the information button beside unfamiliar calendars.
Delete or unsubscribe from the unwanted calendar. Use Report Junk for an unwanted invitation when available.

Get help if

You followed an event's link and entered information, installed software, or accepted unfamiliar device-management settings.