The Covid-19-causing coronavirus is mutating as it spreads around the world in the pandemic, but none of the mutations currently documented appears to be making it able to spread more rapidly, scientists said yesterday. 

In a study using a global dataset of virus genomes from 46,723 people with COVID-19 from 99 countries, researchers identified more than 12,700 mutations, or changes, in the SARS-CoV-2 virus.

"Fortunately, we found that none of these mutations are making Covid-19 spread more rapidly," said Lucy van Dorp, a professor at University College London's Genetics Institute and one of the co-lead researchers on the study.

She added, however: "We need to remain vigilant and continue monitoring new mutations, particularly as vaccines get rolled out."

Viruses are known to mutate all the time, and some - such as flu viruses - change more frequently than others.  Most mutations are neutral, but some can be either advantageous or detrimental to the virus, and some can make vaccines against them less effective. When viruses change like this, vaccines against them have to be adapted regularly to ensure they are hitting the right target.

With the SARS-CoV-2 virus, the first vaccines to show efficacy against the disease it causes could get regulatory approval and begin to be used to immunise people before the end of the year.

Francois Balloux, a UCL professor who also worked on the study, said that its findings, for now, posed no threat to Covid-19 vaccine efficacy, but cautioned that the imminent introduction of vaccines could exert new selective pressures on the virus to mutate to try to evade the human immune system.

The research team from Britain's UCL and Oxford University, and from France's Cirad and Université de la Réunion, analysed virus genomes from 46,723 people with Covid-19 from 99 countries.

Among more than 12,706 mutations identified, some 398 appeared to have occurred repeatedly and independently, the researchers said.