“If doctors could routinely test to confirm who has fought off and become immune to Covid-19, it would eliminate the practical need or rationale for those protected millions to get vaccinated. It would also allow them to avoid even the slight risk of serious vaccine side effects.
Unfortunately, virologists say no commonly-used test can detect with certainty whether a person is immune. A common misconception is that antibody tests can make that determination. But experts say immunity after infection or exposure often comes without a person producing or maintaining measurable antibodies.
Because of that reality, people who have had asymptomatic infections — infections where they suffered no symptoms — have no easy way to know that they’re immune. However, a growing body of evidence indicates that the millions who know they got Covid can be assured they’re unlikely to suffer reinfection, for at least as long of a time period that scientists have been able to measure. Possibly far beyond.”