Thread by @rvenkayya

THREAD: Vaccines & transmission

The emerging, expected evidence that #vaccines reduce transmission is a game-changer, but the focus on herd immunity can give the impression that we won’t see a benefit until most are vaccinated. Not true. 1/ @apoorva_nyc

https://twitter.com/EricTopol/status/1367487223092760576?s=20

This thread describes a world in which vaccines reduce transmission. Early evidence is promising, although more data is needed to understand magnitude of reduction and differences between vaccines. 2/
nejm.org/doi/10.1056/NE…
@mlipsitch @angie_rasmussen
nytimes.com/2021/02/23/opi…

The value of transmission-reducing vaccines begins well before two people make contact. By reducing infections in a community, vaccines make it less likely for either of those persons to be carrying the virus, reducing risk substantially. 3/
@erinbanco
politico.com/news/2021/03/0…

If a vaccinated person IS exposed, they’re less likely to pass virus to others because:
🔹The vaccine prevents them from being infected; OR
🔹If infected, they're less infectious because symptoms are reduced and/or they shed less virus. 4/

Instead of being a link in a chain of transmission, a vaccinated person can be the end of that chain.

The more people vaccinated, the more chains terminated, and the fewer branches on the chains that continue. 5/

And any vaccinated person who is infected is almost certainly protected from severe disease and death.

We don’t need herd immunity or 100% reduction of transmission to see these benefits. 6/

Every time a person is vaccinated, it gets a little harder for the virus to be transmitted through a community, and that reduces the risk of *any* interaction in a community by a small degree.

So every person who is vaccinated is helping to protect the *entire* community. 7/

And just as virus transmission is exponential, so is the impact of a transmission-reducing vaccine on cases in a community. 8/

If this sounds like the argument for wearing masks, it should. Vaccination can protect both the person vaccinated as well as the people around them. But unlike masks, vaccine protection works 24/7 without a person even thinking about it. 9/

Because vaccines are unlikely to be 100% effective at stopping transmission, vaccinated people should wear masks around unvaccinated people as long as (a) a lot of virus is circulating; and (b) many people remain unvaccinated. But this will be relaxed & removed over time. 10/

We need to learn more about the impact of vaccination and individual vaccines on transmission, but any effect will be helpful, and the early evidence and prior experience is very promising. 11/

If we can achieve global equitable access to any of the vaccines that have been shown to be safe & effective, which is our moral obligation, they’ll help us to bring an end to the worst human, economic and societal impact of this pandemic. Everyone has a role to play. 12/end

For those who haven't seen the full thread, these statements only apply to vaccines that reduce transmission.

My goal was to illustrate that these vaccines can have a meaningful impact in the absence of herd immunity or 100% prevention of transmission.

https://twitter.com/rvenkayya/status/1367544907603312645?s=20