On 25/02/2021 22:19, bert wrote:

Totally illogical. If you have been vaccinated what have you to fear?

Several things;

Vaccination will not necessarily prevent you being infected, all it can
do it improve the bodies response, making it faster and more effective.
The aim being to prevent serious illness, hospitalisation, long term
complications and/or death. The immune response can only do its thing,
once it has already been "invaded" by the pathogen. So is still likely
that a small window of time could remain where you could transmit the
infection on. Hence vaccinated people tooling about like they are now
captain Teflon are a liability for everyone else.

Mutations are a continued and natural part of the lifecycle of a virus.
Since mutations are random, a few will improve the virus' ability to
survive and reproduce, but many will lower it. Normally when there is
already a dominant and successful strain in broad circulation, even
potentially successful mutations may still not actually succeed since
too many of the hosts they reach already have a sufficiently similar
infection from a another strain[1], that they can't compete.

This does however make the start of a vaccination program a particularly
risky one since it will drive down the reproductive rate of the current
dominant strains, giving more scope for variants to gain traction. If
these also happen to be less well targeted by the vaccine, then you can
quickly find yourself back at square one. The way to minimise the rate
of production of viable mutations, is to reduce the number of infected
hosts.

That means that all the non vaccine protective measures need to stay in
place for longer than may at first glance appear necessary in order to
keep driving the overall number of infections down as low as possible.


[1] It has been demonstrated that it's possible to contract two
different COVID 19 variants at the same time, although this is thought
be very rare.


--
Cheers,

John.

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