[Avodah] Vaccinations - Rav Asher Weiss

[Zev Sero]

On 8/1/19 12:59 am, Alexander Seinfeld via Avodah wrote:
> He uses the example of a makaa (fence around a place where one could 
> fall). How effective is this fence, assuming it is built and used 
> correctly? Can we agree that it is 100% effective at its job of 
> preventing falls? (Excluding building errors or misuse such as climbing 
> over it)? The vaccination is not like that – even when made and used 
> correctly, we still expect about 1 in 1,000,000 children to die from it. 
> That’s pretty scary, and the ma'aka mitzvah does not readily and 
> obviously apply here. The essence of a ma’aka is that it is a 100% 
> protection against a possible danger (nobody knows the level of danger 
> without a ma’aka, I propose 1 in a thousand (.1% percent as a good-faith 
> estimate). To repeat, a 100% protection against a 0.1% risk. But as I’ve 
> already shown, a vaccination is not a 100% protection and the risk is 
> low but not zero.

Nothing has zero risk, or a zero failure rate.

As you point out parapets have two modes of failure: defective 
construction, and people climbing over them; however uncommon these are, 
that's a non-zero failure rate; not the 2% of the MMR vaccine, but let's 
suppose 0.02%. (Against that, consider that the risk to the person whom 
the remedy fails is much higher for the parapet than the vaccine; the 2% 
whom the vaccine fails to protect will, *if exposed*, catch one or more 
of the three diseases, with a >99% chance that they will survive with no 
lasting injury, whereas the 0.02% -- or whatever the true number is -- 
whom the parapet fails stand a >99% chance of injury or death.)

Parapets also carry a minuscule risk, e.g. from people striking their 
heads against them, which is almost certainly significantly *higher* 
than the corresponding 1/1M risk from the MMR vaccine.


-- 
Zev Sero            A prosperous and healthy 5779 to all
zev at sero.name       Seek Jerusalem's peace; may all who love you prosper