> Do you think some|most|all parents will consent to their children having one or more vaccinations against Covid19 when "the likelihood of children having significant detriment if they catch Covid-19 is very, very low" (quote from UK Health Secretary, Matt Hancock)[1]
How often do those kids see their Grandma?
Even in your grossly optimistic scenario, you're assuming that those parents (and kids) are willing to risk spreading COVID19 to their Grandparents, killing them. There's plenty of grandparents who are unable to receive vaccinations due to high-risk conditions (heck: Pregnancy hasn't been tested yet: so Pregnant parents this year are going to have to go unprotected).
Preventing the spread through the use of vaccines is an obvious win. The studies are pending, but vaccines in the past have prevented spread (even lesser-effective vaccines, like the 2014 flu vaccine).
When we're looking at 95% efficacy against symptoms (Pfizer / Moderna's vaccines), the amount of "prevents the spread" is likely going to be very very high.
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If you have a family of 5, and the mother is Pregnant, the best way to protect the mother (and potential #6 child) is to vaccinate everyone else. The family unit achieves herd immunity (>66% vaccination rate), making it very hard for COVID19 to spread to the mother.
There's a HUGE number of untested people with regards to the vaccine. Everyone who has been proven safe with the vaccine should be vaccinated. For the sake of pregnant mothers, cancer patients, and yes children (for now). Hopefully, when children are tested and proven safe, we can vaccinate them too afterwards.
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Alternatively, we can start testing at-risk patients, like pregnant women and cancer survivors. Which seems like the "greater evil" in my opinion. It makes more sense to test children and inoculate them, than to test higher-risk groups.