The ten fold infectious D614G mutation: What does it mean for COVID spread, vaccine development?

Even as COVID-19 continues to spread globally, Malaysian authorities made a startling revelation yesterday about a 10 times more infectious strain of coronavirus traced back to South Asian countries, the 'D614G' coronavirus strain.

While it's still too early to confirm as to how consequential this novel coronavirus strain could be, it was observed that the person who broke his quarantine carried the same strain and infected as many as 45 people. The revelation spoke of what many experts were afraid of- the worst might be yet to come.

In the past months, the strain has been found to be in circulation in New York and pockets of Italy, which were, at one point one of the worst affected cities globally and also witnessed high hospitalization and mortality rates and now, the infamous strain is gaining popularity for all the dangers it could expose us to. There are also contrasting researches which suggest that much like any other viral strain, D614G could be nothing but a similar viral mutation which could only affect a small group of people. But the actual question which remains at large is- how much of a real threat does it actually pose for humanity?

Here is a detailed explainer which can throw some light on what we can expect about the infamous coronavirus mutation.

The novel coronavirus, much like other viruses undergoes many mutations through its life-cycle. However, till date, the one single strain which was termed dangerous has been D614G.

Malaysian sighting doesn't make it the first time scientists have sounded alarm over the dangerous infection strain. Early reports suggested that as many as 97% of samples collected carried this strain. The virus mutation was first observed in February in some places across Europe when the virus has started to spread to countries across the world.

Technically, D614G is a mutation of the COVID-19 causing SARS-COV-2 virus, present between the virus's spike protein, which is used to enter into the host cells. The naming of the mutation is primarily due to its chemical make-up. According to science experts, the viral mutation changes the positioning of the amino acid at '614' from D (which stands for aspartic acid) to G (glycine). Hence, the mutation is earmarked as D614G.

A study published in the scientific journal, Cell, observed that of 999 samples tested across the UK, patients who were detected with the D614G strain had a higher viral load than others. Another study published in the same journal also correlates to the fact that a higher viral capacity may showcase greater infectivity patterns. As compared to the original strain of the virus 'Wuhan 1', the present viral strain could infect up to 4 cell lines (under lab study) and is 10 times more infectious.

However, it should be noted that while these studies were conducted to study cell culture in a confined lab study, so it could be difficult to correlate actual viral spread in humans as of now. There is no evidence as yet which suggests the same.

Interestingly, while the viral strain has been associated to infect far more people in one cluster than previously observed, scientists have observed that a higher viral load did not correlate with higher disease severity. Hence, while the virus strain may be more infectious than any other strain in circulation, it isn't associated with strong fatality rates.

Other researches conducted in the USA and UK found that the D614G mutation, found in samples across New York and sections of Italy had similar hospitalization rates as previous mutations of the SARS-COV-2 virus.

One of the biggest complexities surrounding the same is about diagnosis and treatment. If the mutation is difficult to treat, it could shoot up fatality rates. However, no such correlation has been observed up until now. While the mutation made no significant impact on hospitalization, it was seen that pre-existing medical conditions and certain factors such as sex and age did increase a person's risk of catching or developing COVID-19.

The same way, most of the experimental or repurposed drugs used till now did not show any reduced efficacy depending on the viral load. More research will be needed before we concluded whether or not this specific mutation is relatively harder to treat or not.

Whenever a virus mutation comes to light, it raises queries about how challenging could it prove to be in terms of vaccine development. For the unknown, vaccines are usually devised out of a more traditional or early isolated strains of a virus. In a timeline like the one we are facing right now, when we don't have a vaccine ready, there are also looming questions whether or not we would now be needing different vaccines for different strains of the virus, making it all the more difficult to get a vaccine ready for the masses.

However, biologists, so far, have been quick to confirm that while the mutation brings about changes to the spike protein structure, no such changes have been observed with the ACE2 receptors, which is a critical target of the immune system and hence, any mutation is unlikely to bring around changes to immunogenicity. This would mean that any vaccine would most probably be effective in fighting the virus.

Again, as long as the mutations aren't aggressive, vaccines could still work in protecting populations from infections and reinfections to a certain extent. It all depends on the vaccine's efficacy rates.

To conclude, the current virus mutation in question, D614G might be far more infectious but whether or not it could mean a definite spike in the viral load in humans is still inconclusive. Novel coronavirus, regardless of what mutation might be in circulation, is still scary and bringing in non-pharmaceutical measures such as social distancing, quarantines and of course, disinfection could help curb the spread of the viral infection by a big margin.