Gates Package — page 1050

in cutting down transmission--no one who was vaccinated could pass the pathogen to other people. Perfecting vaccines to block infection entirely is a long-term goal, and in the meantime, we should also create a new type of drug called a transmission blocker. These drugs could be used in combination with vaccines to protect you completely from infection: The vaccine would give you long-term protection from severe disease, and the drug would provide shorter-term protection from any infection. You would use the drug during intense periods of transmission, but if it didn't work or you didn't take it often enough, you would still have the vaccine's protection from severe sickness and death. Rather than attacking the virus in your blood, transmission-blocking drugs would keep it from getting into your blood in the first place. In your mucus--yes, I'm mentioning mucus a lot!--there are particular immune cells that have four binding sites they can use to grab a pathogen and neutralize it. A blocker would teach these cells to watch out for a particular virus (flu or COVID, for example) and latch on to it. Because they have so many binding sites, these mucosal immune cells can attack viruses much more efficiently than the immune cells in your blood. One unpublished paper I've seen suggests that, in mice at least, these cells might provide ten times as much protection.25 The technology behind these blockers is still in its early days, but if we could get blockers to the point where they can be developed quickly--the way mRNA vaccines now can-- and delivered by nasal spray or pill, they'd be a phenomenal tool for keeping an outbreak at a low level. .