I suspected that, sooner or later, the Bloomberg story with the headline “Malaysia detects new coronavirus strain that’s 10 times more infectious” would go viral. It would appeal to a lot of people who have heard of virus mutations before and who feel that this validates their belief that the Coronavirus is mutating, vaccines will not work and that we are in an apocalyptic cycle of doom. Popular media loves alarmist headlines, the average person is susceptible to sensational statements and anecdotal evidence, while scientists play catch up trying to educate the masses (and politicians). Stories of Coronavirus mutations have been infecting social media for a long time but Bloomberg is an important news source and it is surprising to see this headline. The contents of the article are OK, but then who reads past the headlines these days?
The D614G variation (also known as the G614 strain) is not new; it has been known for some time and is known to be the dominant strain in most countries, including the U.S. It may be new to Malaysia. It is known to be more resilient and infectious, but not 10x and it is no more fatal or severe than the earlier D614 strain. The 10x number came from the country’s Director-General of Health Noor Hisham Abdullah in a Facebook post without citing any study; he subsequently pointed to this comprehensive article (see link below) that actually debunks the claim and provides important background about D614G with links to many studies, so perhaps his words meant something else.
For that matter who knows what 10x more infectious means; surely, it does not mean that R0, the basic reproduction number, is 10 times bigger.
The article linked above is very comprehensive and informative. Please take a look at it when you get a chance.
This diagram from the paper “Tracking Changes in SARS-CoV-2 Spike: Evidence that D614G Increases Infectivity of the COVID-19 Virus” (by Bette Korber et al from Los Alamos National Laboratory and other organizations) shows that G614 is well-known and has become the dominant strain since March/April of this year. So, what’s new?
The authors summarize their findings as follows —
- A SARS-CoV-2 variant with Spike G614 has replaced D614 as the dominant pandemic form
- The consistent increase of G614 at regional levels may indicate a fitness advantage
- G614 is associated with lower RT PCR Cts, suggestive of higher viral loads in patients
- The G614 variant grows to higher titers as pseudotyped virions
It finds that G614 is more infectious, but does not claim a 10x increase in infectiousness.
This often cited paper “Making Sense of Mutation: What D614G Means for the COVID-19 Pandemic Remains Unclear” by Nathan D. Grubaugh, William P. Hanage and Angela L. Rasmussen, also sheds light on Coronavirus mutations —
The authors state that such studies suggest, but not prove, increased viral transmissibility. Their review noted that:
- Increased viral shedding or RNA does not reflect viral transmission capacity. Also, most human transmissions occur in the presymptomatic stage, and the above study examined patients in their symptomatic stage.
- Cell culture work does not necessarily translate to humans. Because, as they explained, “These assays don’t account for the effect of other viral or host proteins and the parade of biochemical host-pathogen interactions that must occur to support infection and transmission.”
- Does the D614G mutation (or the G614 variant) enhance viral spread? Science has no conclusion yet.
- The authors cited three studies showing that antibodies built from natural D614 and G614 infections can cross-neutralize — meaning that antibodies made against D614 could work for G614, and vice-versa. The D614G mutation is therefore unlikely to have a major impact on the efficacy of vaccines currently in the pipeline, some of which exclusively target the RBD.
Prof. Andrew Rambaut and others have studied this in detail and have yet another preprint publication on the subject — “We do find evidence that D614G increases the rate of transmission even when accounting for potentially confounding factors like founder effects but it is hard to give a precise estimate of by how much. It doesn’t make the virus more (or less) pathogenic.”
The authors conclude -
- Phylodynamic analysis does not show a significant increase in growth rates for clusters with the 614G variant, but population genetic modelling indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage.
- We do not find any indication that patients infected with the Spike 614G variant have higher COVID-19 mortality, but younger patients have slightly increased odds of 614G carriage.
- Despite the availability of a very large data set, well represented by both Spike 614 variants, not all approaches showed a conclusive signal of higher transmission rate for 614G, but significant differences in growth, size, and composition of these lineages indicate a need for continued study.
Epilogue
To summarize -
- This is not a new mutation.
- The G614 strain is already the dominant strain in the world. Most people in the U.S. have this strain.
- It is not 10x more infectious than the previous dominant strain, although it has proven to be more infectious in lab tests.
- There is no evidence of it being any more fatal and it does not cause more severe disease.
- The G614 mutation (and dozens of other mutations) have been studied and documented
- Scientists would be shouting from the roof-tops with a finding of 10x infectiousness.
Stay calm, stay informed, stick to reliable sources, stay safe and stay strong.
P.S. Bloomberg has now changed the title of the article to “Southeast Asia Detects Mutated Virus Strain Sweeping the World.”
