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Comment by lbeltrame | Hacker News Reader

True asymptomatics are rare in the infected population. Most of people are presymptomatic (=they will develop symptoms), and their peak infectiousness is one or two days before symptom onset, according to published data.

> If millions of people take your early-release vaccine and it's ineffective

Phase 3 studies on Moderna, Pfizer, and AstraZeneca vaccines have shown that they are effective (and nowhere close to an "early release"). Statistics don't lie in that regard.

> This apparently is an issue with the Russian vaccine because of the way it's introduced to the immune system.

I'm not aware of any of such issues. Do you have a primary source I can look up?

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This paper is the specific issue I was talking about [0]. Individuals who were Ad5 seropositive had an immune response to subsequent Ad5-based treatments. They developed an immunity to Ad5 which is just a delivery vector for the viral protein you're trying to introduce.

The CanSino vaccine also uses Ad5 as it's viral vector. An immunity to Ad5 from say Sputnik V would apparently prevent you from being able to get the CanSino one should Sputnik V prove ineffective for you. You'd also not be able to get a booster of Sputnik V later.

There's lots of adenovirus strains and a few other vaccines are using them for their delivery vectors. Ad5 is an edited adenovirus that has it's replication system retarded/removed. There's other articles I've seen but can't find now lamenting the use of Ad5 specifically. There was also the STEP study that showed increased HIV susceptibility in people that had received Ad5 vaccines.

I am not a medical professional but I do understand immunology is extremely complex. Effective vaccines in vitro aren't necessarily effective in vivo. There's also complex issues around dosing which is part of human trials. Even if a vaccine is "effective" it's not necessarily obvious or known what sort of dosing is appropriate for wide deployment in the general population. A completely "effective" vaccine at the wrong dose can end up being ineffective.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756115/

Sputnik is two vectors: Ad26 and Ad5. That looks like the reason why they kept having a high efficacy (today's press release from Gamaleya says 92%).

Dosing is done in Phase 1 trials, which also included antibody level testing. This has been already taken into account in the current trials.

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