How much of a threat is the South African variant?

For residents of six London boroughs, as well as those in Smethwick in the West Midlands, the partial relaxation of lockdown rules this week hasn’t quite gone according to plan. They’ve had a day out in the sun, alright, but not necessarily sitting enjoying food and drinks in a pub garden – more likely they have been standing in a long queue to get ‘surge tested’ for the South African variant of SARS-CoV-2, the virus which causes Covid-19.

So how much of a threat is the South African variant? In spite of anecdotal claims from South Africa that the new variant was affecting younger people, there is no evidence that it causes more severe illness. But it has been estimated to be 50 per cent more transmissible than the variants which dominated the first surge of Covid-19 last year. 

Yet that does not in itself necessarily make it a great problem. Britain has already coped with the Kent variant, which is also more transmissible than those in circulation last year. A few weeks ago, deputy chief medical officer Jonathan Van-Tam asserted that the South African variant does not have a transmissibility advantage over the Kent variant and that it is therefore unlikely to become the dominant variant in Britain.

The greater problem is its apparent greater resistance to the vaccines currently in use. A South African study last month found the AstraZeneca vaccine to have an efficacy of only 21.9 per cent against the new variant – compared with an efficacy of 76 per cent measured in US trials (where other variants are dominant). That first figure is way below the 50 per cent efficacy rate required for approval by the US Food and Drug Administration, for example.

As for the Pfizer vaccine, its record against the South African variant has been more mixed. Earlier this month, Pfizer claimed that it had been found to be 100 per cent effective against the variant – albeit in a small trial involving only 800 people, only nine of whom in the control group caught the disease. 

Today, news breaks of an Israeli study which comes to a different conclusion. The South African variant is not prevalent in the country, accounting for just 0.7 per cent of cases of infection among unvaccinated individuals. However, this climbed to 5.4 per cent of cases among those who have been vaccinated – suggesting that the variant is better at breaking through the vaccine than are other variants.

All this said, Pfizer has claimed that its vaccine can be tweaked to deal with any variants, and that this would only take a matter of weeks. Other vaccines, too, continue to be developed to take new variants into account. Therefore, in the longer run, the South African variant should not threaten efforts to control Covid by vaccination. 

But it could mean that those who have already been vaccinated in Britain may have to return for an extra dose of tweaked vaccine later in the year. In the meantime, surge testing should give us an idea of whether Professor Van-Tam was right when he said the South African variant was unlikely to become dominant here.