Generally no.
A few larger companies do.

I’m pretty sure it’s a global Android feature that doesn’t have anything to do with Firefox specifically.

Slightly longer AI summary by Kagi

Researchers have developed a novel vaccine that targets senescence-associated glycoprotein (SAGP) expressed in inflamed brain cells linked to Alzheimer’s disease. When tested in mice, the vaccine reduced amyloid deposits, decreased inflammatory biomarkers, and improved the animals’ awareness of their surroundings. This suggests the vaccine may lessen disease symptoms. The vaccine targets activated microglia cells which play a role in brain inflammation that can worsen cognitive decline. By removing toxic microglia, the vaccine may control inflammation and ultimately repair deficits suffered in Alzheimer’s disease. If successful in humans, the vaccine could be a major step forward in delaying or preventing the disease.