8915 is a Series of forms used for disaster reporting. Each is a Cycle of three years. the 8915-C is for disasters in 2018, to provide the info into 2019 and 2020 for that same disaster.

You want 8915-E for covid tax year 2020. That will be 8915-E for the three year cycle: 2020, 2021 and 2020. And, there is always the possibility of a disaster in one year not having that person's three year cycle begin until the following year, so really, they are each good for four tax years. Same form "suffix" for the same one disaster cycle filing, in each year it is filed on.