CDC does not recommend quarantine if you recovered from COVID in the last 90 days. Ergo, the CDC does recognize natural immunity to covid.

by Settlemente

From the CDC’s travel recommendations.

Do NOT travel if…

You have been exposed to COVID-19 unless you are fully vaccinated or recovered from COVID-19 in the past 90 days.

So why not get tested for COVID every 90 days? Just keep taking covid tests until one hits positive or argue you have presumptive COVID based on symptoms.