Scientists will vaccinate all the adults in a single city to see whether a COVID-19 vaccine will reduce cases.
The researchers saw "nodules" at the back of patients' eyes, which can be signs of inflammation or direct damage to the eye.
For months, scientists have wondered whether past exposure to seasonal coronaviruses that cause common colds might prevent people from getting a severe case COVID-19.
Known as CAL.20C, the variant now accounts for nearly half of COVID-19 cases in Southern California.
You have likely heard that Pfizer's COVID-19 vaccine efficacy is 95%, Moderna's is 94% and Johnson & Johnson's is 66%. But what do these numbers actually mean?
In a study of 43 men who had recovered from COVID-19, nearly 20% had azoospermia, or the total absence of sperm in semen.
Amid a shortage of vaccine supplies and the threat of emerging coronavirus variants, such an approach might provide an answer for both.
Experts are particularly alarmed by this variant because of its potential to "escape" protection from current vaccines.