Viruses mutate - so what is happening is not surprising.
The mutations seen in South Africa change the part of the virus that the vaccines target.
It means all the vaccines that have been produced so far are likely to be affected in some way.
Trials for Novavax and Janssen vaccines that were carried out in South Africa showed less effectiveness against this variant. Both are currently before the UK regulator.
Therefore the news about the Oxford-AstraZeneca does not come out of the blue.
The fact it now only has "minimal" effect according to reports is concerning - the other vaccines showed effectiveness in the region of 60% against the South African variant.
But we should be careful about rushing to judgement. The study was small so there is only limited confidence in the findings.
What is more, there is still hope the vaccine will prevent serious illness and hospitalisation.
What this once again illustrates is the pandemic is not going to end with one Big Bang. Vaccines are likely to have to change to keep pace with the virus.
Progress will be incremental. But vaccines are still the way out of this - and as things stand they remain very effective against the virus that is dominant in the UK.
BBC News.