Hi there
This is Arman, the founder:
This API is not deprecated and most of its parts work perfectly fine and it’s going to work at least for 3 or more years.
however, there are some parts in this project that need to be optimized.
But, I don’t have enough time to fix those little issues right now. I planned to do it in the next 4 months.
For now, here is the suggestion:

As you probably know, we keep our database updated with the data, fetched from some APIs or excel files.
Finding these sorts of APIs is easier than you think. Just take a look at postman gathered APIs.
If you have concerns about vaccovid API, you can easily fetch the data that you think is outdated or not accurate, from other sources. And still, use the correct data from this API.

Hope I guided you enough.
Bests 😉