News headlines have carried the alarming claim that COVID-19 has mutated into ‘a new more infectious strain’, just as some countries appear to have passed the peak of the pandemic and vaccine development is making headway.

This new finding follows research that has looked for genetic changes in SARS-CoV-2 (the virus that causes COVID-19) that appeared to be making it more successful at infecting people. The research identified a small change in the genetic makeup of the virus, called D614G, which alters the protein ‘spikes’ on its surface.

Global tracking showed that only about 10% of viral samples contained this change before the start of March, but this rose to 78% by mid-May. People infected with this form of the virus appear to have more virus in their nose and throat, and this might explain how this form of the virus came to be more common.

Reassuringly, this newer variant does not appear to cause more severe COVID-19 disease.

Where did the story come from?

The UK publication The Mirror was among sources to report on the study in question, which was conducted by researchers from Los Alamos National Laboratory and other institutions in the US as well as the University of Sheffield in the UK. It is being published in the journal Cell and has been peer reviewed but has not yet been published in its final format.

What is the basis for the claim?

The genetic sequence of coronaviruses such as SARS-CoV-2 is said to be usually quite stable, but sometimes changes (mutations) may arise. The viruses carrying these mutations may become prolific if the mutations help them to infect more people or ‘get round’ the human immune system.

Identifying this sort of change is important as it could impact how well a vaccine or new treatments might work. Therefore, researchers developed an “early warning” system to look for genetic changes in SARS-CoV-2 that are becoming more common over time.

On 29th May 2020, the researchers reviewed the SARS-CoV-2 genetic sequence database (GISAID) which has collected sequencing data along with geographic location and date of viral sampling since the start of the pandemic.  They identified a change called D614G, which had rapidly become the more common one. This change affects the characteristic ‘spike’ proteins on the surface of coronavirus. These spike proteins help the coronavirus to get into our cells and are the target of most vaccines in development.

Before March only 10% of the viral samples demonstrated this change, but by the end of March, it had become the predominant variant across the globe (with a few exceptions such as Iceland). By mid-May, 78% of viral samples collected globally carried the D614G change.

Researchers in Sheffield looked at clinical data for around 1,000 patients with COVID-19 and which form of the virus they had. They found that people infected with virus carrying the D614G variant had more of the virus in their nose and throat swabs than those infected with the older forms of the virus.

Importantly, there was no difference in disease severity between people infected with the original form of the virus or this new variant. Also, researchers found that the antibodies produced by a small sample of 6 people who had COVID-19 were still able to “neutralise” virus carrying the newer D614G variant and stop it infecting cells in the laboratory.

Further study needs to look into the potential implications of this new variant, including that for vaccine development.

What do trusted sources say?

Understanding changes in the genetic sequence of the virus are important for researchers and healthcare professionals studying the virus and developing vaccines and treatments.

However, the findings do not change national and international guidance for the public regarding infection control measures such as handwashing, social distancing and use of face masks. SARS-Cov-2 is already recognised to be highly infective, regardless of a specific variant.

Analysis by EIU Healthcare, supported by Reckitt Benckiser

 

Citation

  1. Korber B et al. Tracking changes in SARS-CoV-2 Spike: evidence that D614G increases infectivity of the COVID-19 virus. Cell. 2020 Jul 3.

Reading list

  1. Expert reaction to paper tracking mutations in the SARS-CoV-2 virus with possible implications for infectiousnessAvailable at: https://www.sciencemediacentre.org/expert-reaction-to-paper-tracking-mutations-in-the-sars-cov-2-virus-with-possible-implications-for-infectiousness/ (Accessed 9th of June, 2020).