The west Michigan hospital system, which is in the process of merging with Southfield-based Beaumont Health, will grant an exemption to those who have a positive PCR or antigen test for COVID-19 plus a positive antibody test from within the past three months, the health system said in a statement Thursday.

The exemption, the first for a major health system in Michigan, was developed "as new research has emerged" on natural immunity.

"While we still recommend vaccination for people with prior COVID-19 infection, according to this new research, there is increasing evidence that natural infection affords protection from COVID-19 reinfection and severe symptoms for a period of time," the statement said. "Current studies are not clear on how long natural immunity protects from reinfection."