Explainer | Coronavirus: as infectious strain D614G spreads in Malaysia and Philippines, should we be worried?

A new strain of the coronavirus, believed to be more infectious than the original strain from Wuhan in China, has been showing up in parts of Asia. Known as D614G, the strain was recently detected in Malaysia and the Philippines. Malaysia’s director general of health Dr Noor Hisham Abdullah on Sunday said in a Facebook post: “(The virus strain) was found to be 10 times as likely to infect other individuals and easier to spread by super-spreader individuals.” Here’s a look at what makes this strain different from others, and whether people should be concerned. What is the D614G? Also called the “G” mutation, the D614G is a variation of the original strain of the coronavirus that was first reported in China’s Wuhan city last December. Since then, the virus has mutated several times. A study last month by Italy’s University of Bologna found that there are at least six strains of the original coronavirus which caused the pandemic. Its first mutation – the S strain – appeared at the beginning of this year. The G strain emerged from mid-January onwards. The D614G mutation is now the dominant form in the Covid-19 pandemic, making up about 70 per cent of around 50,000 genomes of the virus uploaded in a shared database carrying the mutation. While it is most commonly found in the United States and Europe, its presence has been increasing in Asia since March. How did it appear? Professor Gavin Smith from Singapore’s Duke-NUS’ Emerging Infectious Diseases Programme said that all viruses create copies of themselves during an infection. Viruses, such as the coronavirus or those that cause influenza, generate mistakes during the replication process. These errors turn up as mutations, Smith said. In the case of the D614G strain, the mutation occurs when the amino acid at position 614 changes from D (aspartic acid) to G (glycine). As a result, the initial D614 variant from Wuhan becomes D614G. What makes it different from others? Research has suggested that this strain is more infectious than other strains. In a July study published in the journal Cell, Dr Bette Korber, a theoretical biologist from the Los Alamos National Laboratory in the US, tested samples taken from patients across Europe and the US. She and her team found that while the D614G variant was rare outside Europe at the beginning of March, it increased in frequency worldwide by the end of the month. “All over the world, even when local epidemics had many cases of the original form circulating, soon after the D614G variant was introduced into a region, it became the prevalent form,” Dr Korber said in a report by research website ScienceDaily. Asia’s vaccine race: who is closest to success? The study found that the mutation occurs in the virus’ spike protein – the protruding portions of the coronavirus that are used to enter human cells. The strain was found to be more infectious than the D614 in cell cultures under laboratory conditions. The team also found that patients infected with the D614G virus carried more copies of the virus than those infected with the D614 strain, possibly explaining why it is transmitted more easily. A separate study in June by researchers from The Scripps Research Institute in the US had also found that the strain was 10 times more infectious than the original strain as its spike protein breaks less frequently. The study was published on the online research site bioRxiv and has yet to be peer-reviewed. However, Professor Smith cautioned that these studies may not translate necessarily to what occurs in humans. Other researchers have also pointed out that these studies merely suggest but do not prove that the D614G strain is more infectious. Is it deadlier? The study by Dr Korber also found that the strain is not deadlier compared to others. It found that hospitalisation rates were more dependent on factors such as age and gender. Professor Smith said that there is no evidence to suggest that the D614G strain is deadlier. He added that the strain has simply become dominant because those with the strain had entered countries where the spread of the virus was not well-controlled. How did it reach Singapore? Dr Sebastian Maurer-Stroh, deputy executive director of research at the Agency for Science, Technology and Research’s Bioinformatics Institute, said it was likely the strain had been brought into Singapore by travellers, but containment measures had prevented the variant from spreading. In an article by The Straits Times on Monday, Associate Professor Hsu Liyang, an infectious diseases specialist at the National University of Singapore, said the mutation had been circulating in Singapore since February, with thousands of infections there likely to be due to the D614G strain. Professor Smith said there was no cause for worry about the infection spreading in Singapore because there were measures in place to control its spread. Why practising good hygiene won’t weaken your immune system “It shouldn’t matter what virus emerges at the moment because we have safe distancing and people are keeping safe with masks. As long as people keep following such control measures, this mutation change means nothing,” he added. When asked if the virus could burden Singapore’s health care infrastructure if this strain were to spread, Professor Smith said that its transmission rate was not dependent on the genetic make-up of the virus alone but that of people’s behaviour. “You can have the most infectious virus in the world, but if it infects a person who just watches Netflix at home, it’s not going to spread anywhere,” he said. “But if it infects someone who likes to go out and meet friends, that’s when it will spread more. “It’s not about the nature of the virus, but the nature of the individual.” Will vaccines still be effective? Professor Smith said that vaccines will still remain effective against this strain because they do not target part of the affected genome. A spike protein has a “stalk” and a “head”. Antibodies from vaccines attach themselves to the head to prevent the virus from infecting human cells. However, since the mutation for the D614G occurs on the “stalk”, this will not affect how the vaccine works, Prof Smith said. This article was first reported on Today Online.