Virus

If the info from sberman above doesn’t help, see below:

If running iOS 13, check: Settings - Passwords & Accounts - Accounts - Any rogue entries here? If so, delete the rogue account. 

If running iOS 14, check: Settings - Calendar - Accounts - Any rogue entries here? If so, delete the rogue account. 

The problem that you describe likely being very easy to resolve. You don’t have a Virus!

It is highly probable that an inadvertent click on a website link has “subscribed” an additional (unwanted) Calendar to your device - and this unexpected Calendar is exposing unwanted calendar events and sending you unexpected “virus” or other warnings. 

Given that infecting a non-jailbroken iPad/iPhone with actual malware is incredibly difficult, this technique is employed by malicious Actors to fool or encourage you into doing something untoward - more often than not, parting with personal or financial information leading to fraud or attempted extortion.

Let’s check for what’s out of place...

iOS/iPadOS13 and earlier: Settings > Passwords and Accounts

iOS/iPadOS14: Settings > Calendar > Accounts

Look for an “account” that shouldn’t be in the list of accounts - as this will likely include the Calendar that contains all the unwanted events. When you find the suspect account, tap - then select Delete Account. This should resolve the problem in its entirety.

I hope you find this helpful in finding the source - and in resolving the issue if an unexpected Calendar is found.

You posted in the iPad community.

The place to click on an iPhone is “Calendars” in the bottom center.

Open the Calendar app. Assuming you’re using an iPad, click the calendar-like icon in the upper left. Remove any calendars you don’t recognize.