NAD+ (Nicotinamide adenine dinucleotide) is a compound that “can exert both antiviral and anti-inflammatory effects in mice and humans, which might be beneficial during coronavirus disease 2019 (COVID-19) infections.” As we get older, NAD+ decreases and, on top of that, viral infections lessen our NAD+ stores further.
The study explains that “NAD+, as an emerging regulator of immune responses during viral infections, may be a promising therapeutic target for coronavirus disease 2019” and “interventions that boost NAD+ levels might promote antiviral defense and suppress uncontrolled inflammation.”
https://www.sciencedirect.com/science/article/pii/S1471490622000254