Re:Delta Variant
by lamontcg on Tuesday July 13, 2021 @01:20PM
(#27823555)
To be clearer: it makes no sense that delta would have higher transmissibility, that it would be due to spike protein mutatations and that its mechanism would be higher ACE2 binding and higher viral load (and faster time to symptoms) and yet it would be less virulent/deadly. Those statements are in conflict, so if all the preceeding facts are correct then its most likely that the low IFR is due to vaccination and natural immunity from last year.
> By far, the most widely studied trade-off involves transmission and virulence (Anderson and May, 1982; Frank, 1996; Alizon et al. 2009). Transmission and virulence are linked by within-host replication: increasing parasite abundance increases the likelihood of transmission, but also increases the likelihood of host death; mathematically, this assumption can be formalized by making transmission rate β an increasing function of parasite-induced mortality rate ν. Nearly all of the literature we summarize below assumes this trade-off.
The trade-off hypothesis should apply in this case specifically because the proposed mechanism is via improved spike binding to ACE2 and that it has been claimed that increased viral loads have been observed.
This wouldn't be a worry for anyone vaccinated, of course, but for still immunologically naive people (antivaxxers in the first world, and those without access to vaccination elsewhere) then Delta should be of greater concern.
> By far, the most widely studied trade-off involves transmission and virulence (Anderson and May, 1982; Frank, 1996; Alizon et al. 2009). Transmission and virulence are linked by within-host replication: increasing parasite abundance increases the likelihood of transmission, but also increases the likelihood of host death; mathematically, this assumption can be formalized by making transmission rate β an increasing function of parasite-induced mortality rate ν. Nearly all of the literature we summarize below assumes this trade-off.
https://www.cambridge.org/core/journals/parasitology/article...
And also all of:
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1420-9101....
The trade-off hypothesis should apply in this case specifically because the proposed mechanism is via improved spike binding to ACE2 and that it has been claimed that increased viral loads have been observed.
This wouldn't be a worry for anyone vaccinated, of course, but for still immunologically naive people (antivaxxers in the first world, and those without access to vaccination elsewhere) then Delta should be of greater concern.