“I think the important question is: Does it prevent those who get the vaccine from spreading it to others? Confirmed infection doesn’t necessarily mean no infection, could just mean very low (unconfirmed/undetectable) viral load.”
It lowers the probability by more than an order of magnitude.
Low viral load itself also makes those people who are infected, less infectious to others (compared to someone with a higher load).
In turn, when people are infected by an initially smaller amount of virus, their individual outcomes are also better - less likely to have symptoms, serious illness, die or transmit to others.
The virus takes longer to replicate to a high load, and the immune system has more time to respond - further impeding viral growth along the way. It is kind of race between offense and defense, to see which can overwhelm the other with sheer numbers.
Yes, seems the main issue is the slow immunoresponse to CV19 and getting it to ramp more quickly (relative to the virus replication) which is obviously benefited by keeping the viral load as low as possible while the immune system ‘learns’ how to respond to the infection. Also why I am dismayed that the CDC/FDA/NIH didn’t really put much effort into researching possible treatments, instead betting on a vaccine but to the possible detriment of half a million Americans. Most of the research on treatments comes from private sector clinicians and foreign governments like Australia. There was little reason for us not to do both (investigate treatments and develop vaccines) except perhaps money and the risk that a successful treatment would make vaccines not just unnecessary but could undermine statistical purity of the vaccine trials (lots of institutional interest in the mRNA platforms for future drug development, so I suspect one of the reasons to undermine investigation into off the shelf treatments was the desire to expand mRNA research). Thanks for your reply.