Counter points to this show are available:
The homeless weren't affected as much as other segments of the population. This Radiolab episode suggests that healthy vitamin D3 levels from being out in the sun often may be the reason.
A hospital in Spain did a double blind study, solid science. In this study, before any vaccines were available for covid, vitamin D3 made the difference between a 7.6% death rate due to covid, and a 0% death rate with vitamin D3. This YouTube video gets very technical, but tells the story.
Back in the 60s, body temperature's effect on fighting viruses was known, that knowledge was lost for a time because of scientists who spoke out, not knowing the whole story, but in 2003, in the aftermath of the previous covid outbreak, a doctor from China documented the need for body heat to fight off covid. Even so, medical professionals in New York set up a covid triage in Central Park during a season when the daytime temperature was in the 50s, and night time temperature was much colder. Just having a PhD behind your name doesn't make you right.