If you're in your 40s and you've had Covid, does that give you a certain amount of immunity?

Everyone who is 0 years old to 150 years old who has had covid has "a certain amount of immunity".

It appears that people who are sicker have longer term immunity vs people who are less sick regardless of age. 

YES but it's adaptive so how long that will last is anyone's guess...

N.Shadows

It gives you antibodies, but it's not known how well these protect from subsequent infections or how long they last

Maybe. You'd have antibodies in your system for 2-3 months which would give you some protection. But I think they're advising everyone get vaccinated regardless, so we can reach herd immunity en masse.

Define certain amount?  People have allegedly been reinfected. So I'm guessing they would tell you no. The science is a bit iffy on this one especially when the variants are tossed into the question. I use Chicken pox as a comparison. Some when they had it as a kid, are immune from every getting it again. Some who had it, can still get it. They can test one to know for sure and then, as in my sons case. Can recommend if they should vaccinated that person to give them full immunity. Covid is a different virus, they are still unsure even how long the vaccinations will last. So the default should be, I can still be reinfected until it has been proved one way or the other.