A really important distinction point to make about the protection afforded by vaccination. This is a general point, but one that is pertinent in the context of COVID-19.
I have seen much of the discussion about the protection afforded to the disease by vaccination as describing it in percentage terms. The numbers around the Pfizer and AZ vaccines are that 1 jab provides about 80% protection which then jumps to over 90% following the booster shot.
With the dialogue being such, it is easy to think that if you went from unvaccinated to 1 shot protected to, finally, 2 shot protected that you have gone from 0% protected, to 80% to 90% +. However, this is not the actual risk faced by you.
The risk to any individual without vaccination varies, but for most of the population under the age of 60, there was a much less than 1% chance of getting seriously ill and dying from COVID-19. Thus, the protection of 80% then 90% (following the first and second doses, respectively) is in terms of reduction of the already small risk that was posed.
The protection in percentage terms issued by the vaccine manufacturers relates to risk of serious illness versus placebo in the trials - not absolute risk. So, of course, the more vulnerable you were to COVID before vaccination, the greater the net effect on your overall protection is from the jab.
For those in the lowest risk groups I think that the argument about getting vaccinated absolutely is utilitarian in value - i.e. societal good. However, I do think this very important point about relative risk reduction is the best argument out there that opposes vaccine passports. Medical interventions (of which vaccines are undoubtedly one) have to be based on the tenet of informed consent. If liberty is restricted if ones choice is 'wrong' then it ceases to be a choice and, as such, genuinely informed consent.
From the outset the problem society has grappled with is being able to perceive and judge risk accurately. The age split in COVID-19 with respect of serious illness shows that as you get further and further down the age ranges, the 'obviousness' of the personal benefit of vaccination drops. The greater the % of the population are vaccinated, the lower the societal utility also becomes for the minority of unvaccinated to become vaccinated. This is precisely where the debate needs to be considered from when we consider whether this needs to be rolled out to children or not.
I offer these thoughts as someone who had their first vaccine - AZ - last week. I also encourage all adults to get the vaccine as the risk of adverse events is tiny when matched against the societal benefits - but, at the same time, we need to understand the risks we are dealing with here in real and tangible numbers.