“On the balance of probability, it’s very likely that this new variant identified in the UK won’t change clinical outcomes,” wrote Dr Adam Barker and Dr Tara Raveendran in a note.
The variant in question, they said, is believed to have certain characteristics including the loss of part of its genome (referred to as the H69/V70 deletion) and a change in the receptor binding domain (RBD) of the spike protein (referred to as the N501Y mutation).
“Mutation in viruses is inevitable and SARS-COV-2 has so far behaved like other human coronaviruses with respect to its mutation rate. The extent of mutation has established five clades - virus families linked by common mutations - around the world and these families differ to some degree with respect to their geographical distribution. However, despite this variation, none of the mutants that have been generated so far have conclusively been shown to alter transmission dynamics or clinical outcomes,” said the healthcare analysts.
The most studied variant so far is D164G and its influence on transmission properties continues to be debated, they reported.
Recently published research, continued the Shore Capital team, identified thousands of mutations that have occurred independently in multiple parts of the world; the authors of that paper tried to investigate their potential impact on transmission properties.
“None of these variants were conclusively shown to impact the properties of SARS-COV-2. As such, so far, it is seemingly rare that a mutation produces a new 'strain' of SARS-COV-2, if we assume 'strain' reflects some change in the characteristics of the virus. Therefore, on the balance of probability, the variant identified in the UK is arguably unlikely to have altered the properties of SARS-COV-2. Secondly, although the potential for the D164G to influence transmission remains debated, there is hardly any data supporting a link between a virus mutation and disease severity.”
What about vaccines?
The UK health secretary also commented that the strain in question would unlikely be resistant to the vaccines currently being or soon to be rolled out.
“It’s very true that a vaccine-resistant strain of SARS-COV-2 would be less likely to arise in the absence of a vaccinated population. This is because viruses mutate and evolve in response to pressure, and so to escape the effect of a vaccine, the virus has to be exposed to the immune system of people who have been vaccinated, given the immune system is what puts pressure on the virus.
“Vaccines induce antibodies, and other immune cells, targeting multiple sites on the virus and a single mutation is very, very unlikely to be able to escape such a broad immune response. Importantly, if “vaccine escape” variants do arise, we will alter our vaccines accordingly to deal with such strains,” said the Shore Capital team.
Potential vaccines for COVID-19 should not be affected by changes in SARS-CoV-2 seen to date, nor are they likely to need to be redeveloped seasonally, according to Australian scientists in a report on BioPharma-Reporter from October.
Concluding, the analysts said that, so far, there is very little detail on this new variant, and further information is awaited from the public health agencies.
“However, it’s safe to say that all viruses mutate and no SARS-COV-2 variant to date has been conclusively proven to alter transmission dynamics or the clinical severity of illness. Indeed, even the progress of the D164G variant (the mutant most suspected of actually being more transmissible) could have arisen entirely by chance and it may not actually be more transmissible than other strains. The debate continues around this issue.
“All the above being said, it is possible that a new mutant could be formed which is more transmissible and/or can create more severe illness. Even though there isn’t a clear precedent for this during the pandemic, it is down to random mutation and selection and Mother Nature is more than capable of surprising us. There’s no evidence currently that that is the case here, but public health agencies must be alert to the possibility that this strain could be different. “
As such, it is important to be cautious and study new variants of the virus if they appear to be growing at a faster rate than other variants and/or they are seemingly associated with different clinical outcomes, they said.
Reducing transmission
A vaccine reducing onward transmission would help to dampen this issue to a degree, commented the analysts.
“This is also a reason why having a vaccine which reduces onward transmission of the virus (and not just severity of illness) would be beneficial. By reducing the pool of actively replicating virus, you reduce its ability to mutate and hence select more successful variants.”
They noted that future data from the ongoing/completed vaccine trials will help to understand if the current vaccines are capable of doing this. The AstraZeneca/University of Oxford candidate has some preliminary evidence that it can (although from a small sample size) and the Pfizer/BioNTech and Moderna candidates have such a high efficacy, it arguably suggests an impact on ongoing transmission, they wrote. “But more data is needed to confirm these findings.”
