It's essentially the exact same metrics as a sales or marketing funnel.
Total traffic is the largest driver and after that it's the conversion rates of the other parts of the funnel
It's pure funnel maths since the top of funnel is growing so fast and the conversion rates all the way down are also growing.
If Facebook and Google ban your campaign, it stops. That is a vaccine or a lock down.
After a while, either growth collapses because all your target market (Total Addressable Market) is saturated (Herd imm.). Pretty difficult as TAM is so big for COVID.
It's what stops fad products like Beany Babies. The TAM gets saturated.
Most campaigns suffer this over time.
See, its not about politics, its just the numbers game.
It also works for pandemics.