Los Angeles, California - Phoebe Bridgers is the latest star to bar unvaccinated individuals from attending her performances as the highly contagious Delta variant of Covid-19 continues to spread across the United States.

On Monday, the Motion Sickness hit-maker announced that all forthcoming shows on her fall Reunion tour have been relocated to outdoor venues. Tickets already purchased for indoor events will be permissible at their outdoor equivalents.

Additionally, fans will be required to provide proof of vaccination to attend Bridgers' concerts in states where such a requirement is allowed. Elsewhere, attendees will need to produce proof of vaccination or show a "negative test result (PCR preferred/Antigen accepted) within 48 hours prior to" entry.

Refunds are available for those unwilling to comply with the updated health regulations. Planned indoor sets at the Anthem in Washington, D.C., and the Orpheum Theater in New Orleans have been postponed indefinitely.

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"In the interest of safety, I've decided to only play outdoors for the upcoming tour," the artist wrote on Instagram.

"We are moving all previously scheduled indoor shows to outdoor venues and we've needed to postpone shows in a couple cities so please check the updated schedule. At my request, there are updated health and safety requirements ... And please wear a mask. I love you. See you soon."

Among the other musical acts demanding evidence of immunization at their US shows are Foo Fighters, the Eagles, Phish, Dead & Company and Maroon 5. And several performers have canceled or postponed tour dates altogether as COVID-19 cases continue to spike.