It’s impossible to be completely certain. However, the first examples of immunity sent occurred in Australia and New Zealand long before they had any Covid-19 circulating. That suggests to me viral interference isn’t necessary to explain the observed phenomenon.
Love your posts, and just to be clear I am a firm believer in the immunity debt hypothesis!
But I'm struggling to see how the described "dose response" actually supports it.
Thought experiment - we have a reduction in transmission due to NPIs that somehow doesn't reduce population immunity. Then we go back to normal disease transmission. Would we not expect the same relationship: bigger reduction in cases leading to relatively bigger rebound, just as a mathematical inevitability?
Looking at the graphs it seems most of the disease types are simply returning to pre-NPI dynamics. The relative increase in the rebound seems to me to be more reflective of how effective NPIs were at reducing transmission of that disease type. E.g. it was very good for reducing transmission of bronchiolitis viruses so cases dropped to almost nothing, and then when they went back to normal that is a massive relative increase. For another disease e.g. tonsillitis where NPIs were relatively less effective at reducing transmission, the rebound was less impressive. We don't need to bring the immune system into it!
I think if there were increases above pre-NPI levels then we would have evidence to suggest another factor at play (e.g. immunity debt). And in reality we did see that, but I can't really see it reflected in the data presented in this paper.
How much of the lower level of other viruses during covid were due to NPIs vs viral interference?
It’s impossible to be completely certain. However, the first examples of immunity sent occurred in Australia and New Zealand long before they had any Covid-19 circulating. That suggests to me viral interference isn’t necessary to explain the observed phenomenon.
Thanks for the clear explanation of immunity debt!
Love your posts, and just to be clear I am a firm believer in the immunity debt hypothesis!
But I'm struggling to see how the described "dose response" actually supports it.
Thought experiment - we have a reduction in transmission due to NPIs that somehow doesn't reduce population immunity. Then we go back to normal disease transmission. Would we not expect the same relationship: bigger reduction in cases leading to relatively bigger rebound, just as a mathematical inevitability?
Looking at the graphs it seems most of the disease types are simply returning to pre-NPI dynamics. The relative increase in the rebound seems to me to be more reflective of how effective NPIs were at reducing transmission of that disease type. E.g. it was very good for reducing transmission of bronchiolitis viruses so cases dropped to almost nothing, and then when they went back to normal that is a massive relative increase. For another disease e.g. tonsillitis where NPIs were relatively less effective at reducing transmission, the rebound was less impressive. We don't need to bring the immune system into it!
I think if there were increases above pre-NPI levels then we would have evidence to suggest another factor at play (e.g. immunity debt). And in reality we did see that, but I can't really see it reflected in the data presented in this paper.
Am I missing something?