SARS-CoV-2: the challenges of mutation and possible strategies

What are SARS-CoV-2 mutations?

Viruses constantly change through variations due to their evolutionary processes and in order to survive. In most cases, these mutations do not have a significant impact on the general population; however, as the mutations multiply, they might provide the virus with selective advantages, such as increased transmissibility. Multiple variants of the virus that causes COVID-19 are circulating globally. Some of the new variants of the SARS-CoV-2 virus (B.1.1.7, B.1.351 and P1) have become more transmissible through favourable mutations.

The first noteworthy new strain identified – B.1.1.7 – was first detected in the United Kingdom in late 2020; the spread of this variant raised concerns as a result of its 30-70% higher transmissibility. Although this variant spreads more easily and quickly than other variants, there is no evidence that it causes more severe illness.

In addition to the variant that appeared in the UK, another significant strain of SARS-CoV-2 – B.1.351 – showed up in South Africa and as of January 2021 had been identified in 23 EU/EEA countries. This variant shares some common characteristics with the variant detected in the UK.

A third variant of the virus – P.1 – emerged in Brazil and contains a set of additional mutations that may affect its ability to be recognised by the vaccine-induced antibody response.

Ongoing studies are investigating whether the disease caused by these new strains differs from the disease caused by other variants, and whether this affects the efficacy of existing vaccines. As the spread of these variants in the EU/EEA countries is high on account of their transmissibility, the European Centre for Disease Prevention and Control (ECDC) assessed the risk associated with these variants as being high/very high.

Impacts on children

According to experts and existing data, the new UK strain of SARS-CoV-2 spreads much more easily than previous strains of the virus. As a result, there have been some suggestions that it has a higher propensity to infect children.

Dr Deepti Gurdasani, Clinical Epidemiologist and Statistical Geneticist at Queen Mary University of London: “Although initial evidence showed a higher prevalence among children in England, this is likely to have been a result of an early spread of the variant at a time when schools were open but the region was in lockdown, with restrictions in place across the UK. The spread appears uniform now, suggesting that children do not have special susceptibility to the variant, but that the variant is 30-70% more transmissible across all age groups.” – Read the full interview of Deepti Gurdasani

Professor Falus, an immunologist at Semmelweis University, agrees and adds that as a result of new variants spreading more rapidly, the proportion of young people becoming infected has recently increased. He also believes that children are less susceptible both to infection and COVID-19 disease and that in absolute terms children are still much more resistant to infection than older age groups.

Impacts of recurrent mutations on existing COVID-19 vaccines

Different types of vaccines against COVID-19 disease have been developed and are currently being developed by scientists. New mutations of the virus raise concerns as to whether existing vaccines will be effective against new strains or not.

Professor Falus believes that the existing vaccines will continue to be effective against new mutations:

Professor András Falus, immunologist at Semmelweis University: “The efficacy of vector vaccines to deliver the genetic code of the S protein into muscle cells is relatively high, and mRNA-based vaccines do not need any vectors in order to achieve the same effect. The probability that all epitopes are mutated simultaneously is very low, so I guess mRNA vaccines will be effective against the variants.” – Read the full interview of András Falus

According to Dr Gurdasani, “Recent data from Johnson & Johnson and Novavax vaccine trials have also shown reduced effectiveness in South Africa, potentially as a result of the variant circulating there, which also carries the E484K mutation. This variant has also been identified in the UK, even in cases not linked directly to travel.”

“We do expect a high degree of protection, but this may be reduced. It is clear that allowing the virus to adapt by allowing high levels of transmission to continue is a risk which may have long-term consequences for pandemic control. The only way to prevent this is to follow elimination strategies, to prevent transmission altogether, as several countries have done.”

🔗 See more opinions of scientists regarding the protection of Covid-19 vaccines against mutations and future coronaviruses in our ESMH article

According to the risk assessment of the European Centre for Disease Prevention and Control (ECDC), Member States should monitor vaccine effectiveness against these new variants and should optimise their use of the limited number of vaccine doses.

The ECDC also recommends that non-essential travel should be avoided and that the testing and quarantining of travellers should continue. The Commission is proposing immediate action to prepare Europe for the increased threat of coronavirus variants. The new European bio-defence preparedness plan against COVID-19 variants – the so-called “HERA Incubator” – will work with researchers, biotech companies, manufacturers and public authorities in the EU and globally to detect new variants, provide incentives to develop new and adapted vaccines, speed up the approval process for these vaccines, and help to scale up manufacturing capacities.

The European Medicines Agency (EMA) also published guidance for vaccine manufacturers with regard to adapting COVID-19 vaccines to SARS-CoV-2 variants.

The Zero-COVID Strategy

Many scientists are calling for a ‘sustainable reduction of COVID-19 transmission’ and as close as possible to zero transmission via strict control measures. These ideas are more popularly known as ‘No COVID’ or ‘Zero COVID’ initiatives.

In November 2020, Dr Gurdasani published, together with a group of 79 researchers, public health professionals and healthcare workers, a call for a sustainable public health strategy for COVID-19.

Later on scientists from across Europe called for an action plan in order to reduce COVID-19 cases in a coordinated manner across Europe.

Dr Deepti Gurdasani : “Half-way measures to contain the spread of the virus do not work, and they lead to repeated lockdowns with devastating impacts on public health and the economy.”

“It may take 3-5 months to fully implement, depending on the initial case numbers in a given country. More transmissible variants make it harder to contain the virus, and it is likely that stricter measures will be needed, including revisions in face-mask and social distancing policies. We will also need better test, trace, isolate and support systems, better mitigation in schools, and effective managed quarantine at borders. Countries that have followed a zero-COVID strategy, such as New Zealand, have won their fight against the coronavirus, have rescued their economy, and returned to normal life,” says Dr Gurdasani.