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At the American Express and (RED) Call a Code (RED) on COVID-19 campaign kickoff event on Wednesday, which was marked by a special performance of Hamilton at Broadway's Richard Rodgers Theatre in New York City, Muñoz tells PEOPLE about the fear he felt when the world went into lockdown in March 2020.
"This isn't just lip service. I feel so grateful to be alive, so grateful to be here. So grateful that the people I love are still here and able to do what we do," he says, adding that being back at the theater where he played Alexander Hamilton feels "like coming home."
Muñoz, who has referred to himself on Instagram as a "doubly immunocompromised" person, explains that the beginning of the pandemic was personally very challenging.
"I did not leave my apartment for three months. And that's not an exaggeration," he says of when lockdown began — and Broadway went dark — early last year.
"I never left the apartment, I was literally in terror about any possible exposure because I'm immunocompromised. I'm HIV positive. And a cancer survivor," he adds. "This is not... there was no chance to be taken."
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The actor and singer says the first time he did leave his home, he was overcome with emotion.
"I remember the first, literally the first day that I dared to leave the apartment, go across the street to the park and sit on a rock," he recalls. "I just I bawled my eyes out, just because of how good the sunshine felt. So that's really how it felt at the start."
"It's not an exaggeration, anyone who is immunocompromised, living through this pandemic, had to be the most careful in every single way," he adds.
"It really is about being so careful. And it's why it's so important to care about masking [and] taking care of yourself, because you don't know who's around you. And what they are living with. Not every illness is seen."
Muñoz, along with Hamilton creator Lin-Manuel Miranda and other stars, attended the Call a Code (RED) on COVID-19 campaign kickoff, celebrating the partnership between American Express and (RED) in supporting equitable access to COVID testing, treatment and vaccines in the world's poorest countries.
(RED), founded in 2006, has historically been an organization focused on the fight against AIDS, but in the wake of the COVID-19 pandemic, it has shifted to deliver private sector money to support the fight against both AIDS and COVID-19.
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