3 ms·

> The (apparent) reality that Delta appears to have a lower IFR and that hospitalization rate for vaccinated people for Alpha or Delta is extremely low do not s

by timr 5y ago

> The (apparent) reality that Delta appears to have a lower IFR and that hospitalization rate for vaccinated people for Alpha or Delta is extremely low do not seem to get the same level of coverage as context for the click/view-generating reporting. Let's be clear: the good data so far is coming from a country with a high vaccination rate. I'm not willing to extrapolate from the UK data to countries who haven't vaccinated their vulnerable populations.

lamontcg 5y ago
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. https://www.cambridge.org/core/journals/parasitology/article/adaptive-evolution-of-virulence-a-review-of-theoretical-predictions-and-empirical-tests/30EC8AB1717BF7A173CF5E051DBB498F https://www.cambridge.org/core/journals/parasitology/article... And also all of: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1420-9101.2008.01658.x 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.

by timr 5y ago

lamontcg 5y ago

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. https://www.cambridge.org/core/journals/parasitology/article/adaptive-evolution-of-virulence-a-review-of-theoretical-predictions-and-empirical-tests/30EC8AB1717BF7A173CF5E051DBB498F https://www.cambridge.org/core/journals/parasitology/article... And also all of: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1420-9101.2008.01658.x 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.