Thinking about suppression v. mitigation for India. One issue that came up is breadth of immunity & future corona flare-ups. Suppression relies on vaccine acquired immunity (VAI); mitigation on natural immunity (NI). This may have implications for comparing loss of life. 1/6
By immune breadth I mean the⬇️in probability of infection/harm as you ⬆️ distance between current & next strain in genetic/antigenic space. 2/6
For old time gamers, think of it as the radius of the explosion when you fire at incoming missiles in Missile Command: bigger breadth is better cuz you knock out more missiles. The bigger the immune breadth, the more protected you are against future strains.* 3/6
If breadth is same, the loss of life from future strains is the same with VAI & NI. (Hidden assumption: the distribution of future strains is same under VAI and NI.) If same breadth, mitigation involves more loss of life from COVID. 4/6
If breadth of vaccine acquired immunity is larger, argument for suppressing til vaccine is stronger: save more lives now and later. However, if breadth of natural immunity is larger, suppression has additional cost: loss of lives from future strains. 5/6
My question is: what is the best/latest evidence, if any, on vaccine breadth generally and for coronavirus's specifically? I imagine there is little on coronaviruses, as there are few such vaccines for humans. 6/6
*One complication is that we don't know where in space the next strain will pop up. My understanding is that, if mutations have low rates of infection, they sometimes disappear. But drift can continue in eg bats & w/ zoonosis pop up again somewhere else in humans.
*(continued) By contrast H3N2 seems to move linearly in genetic space in humans.
Israel's experience w/ H1N1, as relayed by @dan_yamin, is what got me thinking about breadth. Apparently, Israel avoided the initial 2009 H1N1 epidemic cuz it was on holiday; but in subsequent years it experienced a heavy burden because people did not have natural immunity. 7/6
That said, it is not clear this sheds light on breadth. While there was a 2009 H1N1 vaccine, Israel had a lower vaccination rate for that vaccine than seasonal flu in the following year (9% v 15%). 8/6
tandfonline.com/doi/pdf/10.416…
tandfonline.com/doi/pdf/10.416…
