What do we know about the new coronavirus variants?
The strain discovered in the UK is more contagious and the one from South Africa may be more difficult to neutralize with antibodies from recovered patients
BarcelonaThe coronavirus, like all other viruses, is constantly mutating, but not as quickly as the AIDS or flu viruses, for example. If new variants are emerging, the virus circulates a lot, replicates a lot and therefore has a lot of opportunity to mutate. "Every day variants are appearing", Joaquim Segalés, professor at the UAB and researcher at the IRTA's Centre for Research in Animal Health, explains, "but they start to worry us when there are some that are found more frequently than normal". This is what is happening with the variants discovered in England, South Africa and Brazil.
In terms of the pace at which scientific research is advancing, these variants are very recent and there is still little data on their characteristics. For the moment, the one that has been studied the most is the so-called British variant. Epidemiological studies in the United Kingdom indicate that the number of positive contacts among those infected with this variant is 40% higher than with previous variants. In addition, data from the United Kingdom itself and from Denmark show an increase in the percentage of those infected with this variant. This suggests that it is about 40% more transmissible than previous ones. "These are solid data obtained by different research teams and indicate the same thing", Julián Blanco, head of virology and cell immunology at the Institute for AIDS Research (IrsiCaixa), says.
As for the lethality, British Prime Minister Boris Johnson announced on Friday that this variant would be causing 30% more deaths than the previous ones. However, the British government's scientific advisor, Patrick Vallance, explained that the mortality data were still uncertain. In the same manner, the WHO attributed the excess mortality observed to the saturation of the British health system.
Vaccine resistance
In addition to being studied epidemiologically, the British variant has also been subjected to neutralisation experiments to find out whether the immunity it confers once the infected person is not ill anymore, or after receiving the vaccine, is sufficiently effective. It seems that in both cases, disease and vaccine - it has been tested with Pfizer/BioNTech and Oxford/AstraZeneca - the immune response generated by the body is capable of neutralizing the variant with an effectiveness almost equivalent to that of the previous ones. This does not mean that it is not a concern: a more contagious variant can cause more deaths than a more lethal one, because it can cause cases to increase much faster. However, experiences such as Denmark, where the percentage of British variant positives is increasing but the overall case rate is decreasing, indicate that the variant can be contained without a vaccine. Thus, "these measures should not only be maintained but reinforced", Blanco said.
As for the variants detected in South Africa and Brazil, there are still few data. However, they are more worrying. To begin with, they share many mutations with the British variant, so "it is possible that they share a higher transmissibility, although there are no solid data on this yet", Blanco explains. There is also little data on the resistance of these variants to the immunity generated by the disease or by vaccines.
The only study that has been done indicates that antibodies in the blood of people who have overcome the disease would not be able to neutralize the South African variant as effectively as the British or previous ones (of the Brazilian variant there are no data yet). However, as Blanco points out, "translating these results into the response generated by the vaccines is difficult".
According to Maria Bernabeu, head of a research group at the European Molecular Biology Laboratory (EMBL) in Barcelona, "it is possible that because immunity produced by vaccines is better, they can prevent infection by this variant, but this is not yet known". Beyond these considerations, it is interesting to note that antibodies that block viruses are not the only defense that vaccines provide. So-called T-cells are also created, which are able to detect and destroy infected cells and thus stop viral replication.
"Perhaps this cellular immunity is capable of neutralizing this variant", Segalés points out, but he makes it very clear that this possibility remains to be confirmed experimentally. If it were found that current vaccines lose effectiveness against these variants, they would have to be modified. Fortunately, Pfizer's and Moderna's RNA-based vaccines can be adapted in a matter of weeks. In any case, "there is still a lack of data on whether the vaccination strategy needs to be redefined", Blanco explains.
More sequencing
On the British variant, the EMBL issued a statement this week directed towards public health officials and European governments warning that restrictions that may work to reduce the incidence of less contagious variants may not be helpful in stopping the spread of this new variant. In this sense, Bernabeu considers "it is essential that sequencing efforts are increased in order to know which variants are circulating and to apply the appropriate measures". "From the EMBL we have already offered to advise governments and help them implement comprehensive sequencing strategies", she explains.
Beyond the frenetic activity in the field of research, experts stress the importance of maintaining security measures. "As the pandemic is taken under control, the pace of new variants will slow down", Segalés concludes.