LONDON — A global study of more than 12,000 coronavirus mutations has found that none of them appear to have made the virus that causes Covid-19 spread more rapidly.
Researchers at University College London assessed coronavirus mutations in over 46,000 samples taken from people in 99 different countries and concluded the mutations all appeared to be neutral when it comes to speeding up the virus' spread.
The peer-reviewed study, published Wednesday in the Nature Communications journal, identified a total of 12,706 mutations. Of those, 398 strains of the coronavirus were found to have occurred repeatedly and independently.
The researchers decided to hone in on 185 mutations which had occurred at least three times independently during the course of the pandemic.
"Recurrent mutations currently in circulation appear to be evolutionary neutral and primarily induced by the human immune system via RNA editing, rather than being signatures of adaptation," researchers of the study said.
"At this stage we find no evidence for significantly more transmissible lineages of SARS-CoV-2 due to recurrent mutations," they added.
The results of the study come as drugmakers and research centers scramble to deliver a safe and effective vaccine to help bring an end to the coronavirus pandemic.
British pharmaceutical giant AstraZeneca said Monday that an interim analysis showed its coronavirus vaccine had an average efficacy of 70%. The news followed strong results from Pfizer-BioNTech and Moderna regarding the effectiveness of each of their vaccine candidates.
Viruses naturally mutate and scientists have previously said they have observed minor mutations in the coronavirus that have not impacted its ability to spread or cause disease in any significant way.
However, earlier this year, a much-discussed mutant variant of the coronavirus known as D614G was thought to enhance viral transmission. It prompted White House coronavirus advisor Dr. Anthony Fauci to warn the newly-discovered variant might help the pathogen spread more easily.
"Mutations that are fairly common all seem neutral for the virus carrying them. This includes D614G, which according to our analysis is more of a stowaway that got a lucky ride on a successful lineage, rather than a driver of transmission," said Professor Francois Balloux, director of UCL Genetics Institute and one of the study's authors.
"This raises the question why #SARSCoV2 is so well adapted for transmission in humans. A plausible answer is that we missed the early window when it adapted to humans," Balloux said via Twitter on Wednesday.
To date, more than 60.5 million people have contracted the coronavirus, with 1.4 million related deaths, according to data compiled by Johns Hopkins University.