Explained: Why the UK’s mutated coronavirus strain may not be an immediate threat to vaccines

How concerning is this new mutant?

Viruses mutate. It’s part of the virus life cycle; it’s part of their evolution. And mutations aren’t all bad. Some mutations can make the virus much more benign, and some mutations can make them more dangerous for humans. The coronavirus, like the flu and measles, is an RNA virus, prone to mutate much faster.

In the UK’s case, the mutated variant of SARS-CoV-2, called B.1.1.7, has come into focus due to its high transmissibility. This variant has 17 mutations, at least two of those mutations are related to the Spike or S protein and can alter the SARS-CoV-2 biology, according to the Covid-19 Genomics UK (COG-UK) consortium, which does large-scale and rapid whole-genome virus sequencing for the UK government.

It’s the Spike protein that binds to the ACE2 receptor on the human cell surface, allowing the virus transmission. The COG-UK consortium, in its report, says the N501Y mutation increases the binding affinity of the Spike protein to the human ACE-2 receptor; making it highly infectious

How did this mutation happen; is plasma therapy to blame?

There are no definite answers for this. But the report by UK researchers titled “Preliminary genomic characterisation of an emergent SARS-CoV-2 lineage in the UK defined by a novel set of spike mutations”, says that high rates of mutation over a short time could be possible due to long Covid-19 infections (2-4 months longer) in immunodeficient or immunosuppressed patients.

“...these patients are treated with convalescent plasma (sometimes more than once) and usually also with the drug remdesivir. Virus genome sequencing of these infections reveals unusually large numbers of nucleotide changes and deletion mutations and often high ratios of non-synonymous to synonymous changes," the report said.

Convalescent plasma is the plasma from a Covid-19 recovered person that is given to Covid-19 patients with high viral loads. The idea is that the antibody rich plasma of the recovered person will help patients suffering from Covid-19 to fight the virus. The report says that the “intra-patient virus genetic diversity increased after plasma treatment was given”.

Implications for vaccines

Most vaccines against Covid-19 are designed based on the Spike protein to induce neutralising antibodies and protective immunity.

Any major mutation or change of the spike antigen could potentially threaten vaccine effectiveness.

“…there have been seven beta coronaviruses so far of which three have had pandemic potential but only one caused a global upheaval. Why? It has mutations that allow it to adapt so well. Should we be worried about mutations? Well, we certainly cannot ignore them,” Davinder Gill, entrepreneur and former CEO of Hillman Labs, said on microblogging site Twitter.

A senior scientist at a vaccine company that is developing Covid-19 vaccines, who did not want to be named, told Moneycontrol that the company was waiting for more information from UK researchers on whether the new mutant has had any consequence on the vaccine.

A quick test can be done by using antisera obtained from animals in response to the Covid-19 vaccine and testing how it behaves against the new variant. “This will help in finding out whether the vaccine is effective or not,” the executive said.

“Vaccines based on the whole virion (the entire virus particle) — whether they are inactivated or weakened — could withstand (mutations) better than vaccines based on a single antigen, which are likely to be susceptible to potential mutations,” he says.