On one hand, all of these vaccine trials excluded people who already had COVID, so we don't fully know what the effect would be in large numbers. However at lea

On one hand, all of these vaccine trials excluded people who already had COVID, so we don't fully know what the effect would be in large numbers. However at least one person with COVID immunity accidentally got into the Oxford Phase 1/2 trial (according to earlier published results), so we at least know it didn't hurt them. On the other hand, it is generally thought that vaccines can trigger immune reactions that are often much stronger and longer lasting than just being infected, so you would expect there to be a benefit to getting vaccinated even if you already had it. But only time will tell for sure. No one really knows how long immunity of either type will last - we just have to wait and find out!