a new vaccine resistant virus variant if and when it is generated
how likely is this? Seems like vaccines are essentially as effective against all variants as the "original variant" thus far?
We will only know the risk of a new variant with reduced/possibly no sensitivity to currently licensed vaccines when the first cycle of vaccination has been completed (ie: all those over 18 have been vaccinated) and we can also see the level of daily new infections occurring when this has happened. The other important piece of information that is need in order to model risk with any degree of evidence base to predict the likely time until such an 'escape' variant might appear and start to circulate widely in the vaccinated population because of its selective advantage is what fraction of the total daily new infections are occurring in people previously vaccinated. This is required because although clinical trials of the vaccine gave efficacy values for protection against serious disease and death they were not designed to give a quantative value for protection from infection. Without a reasonably accurate estimate of this value it is not possible to build good predictive mathematical models of the risk of such variants arising over time. Yes you can build models that deal with the extremes ie: vaccination completely blocks infection or blocks only disease with no protection from infection but these are of little value other than engendering extreme anxiety or extreme complacency depending on which of the two you choose to believe. It is known from other viral vaccines it is known that they usually give some protection against infection but the practical value of that in terms of eliminating infection from a defined geographical region, that is changing it from always being present in the region ( a so-called endemic infection) to one that is periodically re-introduced (a so-called epidemic infection) is dependent on the infectiousness of the virus in question. So for example in the case of the poliovirus vaccines, if vaccine coverage of ~50% can be achieved infection can be and has been eliminated can endemic disease from all but two countries (Pakistan and Afghanistan) and hopefully through the sterling efforts of the WHO will be the 2nd human infection to be globally eradicated within the next few years. By contrast the much more infectious measles virus requires >95% vaccine coverage to remove it as an endemic infection hence the problems in the UK after the Andrew Wakefield debacle at the turn of the century when the reduction in MMR vaccine uptake saw measles (a disease that stills kills tens of thousands of children globally each year) continuing to re-occur in the UK with resultant loss of the UK's status as being free of measles infection risk!
Turning to the effectiveness of current vaccines against variants that have already been seen, I am afraid that unfortunately your statement is not correct. There is already data from small and somewhat flawed South African trial that suggests that the Pfizer-BioNtec vaccine has reduced efficacy against the so-called South African variant (B.1.351). There are also lab based data that show antibodies raised by currently licensed vaccines have reduced effectiveness against the so-called Brazilian (P.1) variant. This has prompted the vaccine companies to start work on modifying their vaccines to provide 'booster' vaccines that could be used to improve/maintain efficacy against these variants. Whether such boosters will be needed/used will depend on what levels of these variants are seen in highly vaccinated populations such as the UKs.
Hope these clarifications are informative and useful.
Stay safe
Malcolm
