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Could the UK and South African variants be more dangerous?

COVID-19 has already caused the deaths of more than 2,6 million people across the world. Ending the pandemic means developing effective vaccines and drugs. Therapeutic antibodies are currently used to treat patients and there is a worldwide race to vaccinate people after the rapid development of different vaccines.

The therapeutic antibodies and the vaccines approved by various national and international health authorities have proved highly successful against the initial version of SARS-CoV-2 that appeared in 2019 (SARS-CoV-2-2019). The recent emergence of UK (B.1.1.7) and South African (B.1.351) variants is worrying because of the ease with which they are transmitted and have spread throughout the world.

Researchers in New York have recently shown that the UK variant, although resistant to certain antibodies, remains responsive to vaccines. But results obtained from the South African variant are more worrying: it may be resistant to the majority of therapeutic monoclonal antibodies and relatively resistant to different vaccines.

Researchers firstly tested plasma from 20 convalescing patients capable of neutralizing SARS-CoV-2-2019 in spring 2020. Of these 20, 16 had 2.5 times less neutralizing activity against the South African variant while their defences  against the UK variant were intact. The South African variant’s resistance can be explained by the presence of the E484K spike mutation, as already explained in a previous letter (see letter March 1-7 2021).

The researchers also tested these plasma samples against pseudo-viruses, each carrying one of the 8 individual mutations of the South African variant, or all of these 8 mutations (UK 8), or all 9 mutations of the UK variant. The UK 8 pseudo-virus, which has the UK variant spike, gave different results from those obtained with the whole UK variant.

They then evaluated the capacity for neutralization of the serum of 12 participants in trials of the Moderna vaccine, and 10 participants from Pfizer trials, against SARS-CoV-2-2019, the UK variant and the South African variant. Overall, the neutralizing activity against the UK variant was essentially the same for the 2019 virus (SARS-CoV-2-2019), but weaker against the South African variant (12,4 times weaker with the Moderna participants, and 10,3 times weaker for the Pfizer participants).

These results show that current vaccines should still be effective against the UK variant. On the other hand, it would be 10,3 to 12,4 times less effective against the South African variant, which confirms the results of a previous study (See newsletter 1-7 March 2021). This would seem to be worrying in the light of recent reports indicating that the Novavax and Johnson & Johnson vaccines may have shown substantial falls in effectiveness in South Africa. It is therefore imperative to stop transmission of the virus as quickly as possible, using preventative measures as much as possible and accelerating vaccine rollout.

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