This work was done by an exceptional team of virologists at UTMB. It's rigorous and shows pretty clearly that G614 increases infectivity in human lung cells & primary airway cultures.— Dr. Angela Rasmussen (@angie_rasmussen) October 26, 2020
Increased infectivity means the virus can enter host cells and replicate more efficiently.
They also tested this in a hamster model of COVID-19. The hamsters had higher levels of infectious virus in their nasal washes compared to the lungs, suggesting a possible mechanism for how D614G may be more transmissible as previously hypothesized. pic.twitter.com/2ONJR5eAYf— Dr. Angela Rasmussen (@angie_rasmussen) October 26, 2020
Further tweets in the stream:
If hamsters are shedding more virus in their upper respiratory tracts, then they are more likely to be contagious by producing infectious droplets and aerosols with higher concentrations of infectious virus. This is the type of data we need to get to understand this question, BUT
Transmission itself wasn't tested. Ideally, they would have set up two hamster cages in the same room or in cages with shared air to see if G614 was transmitted more efficiently or to more animals than D614 virus.
Since transmission studies weren't part of this paper, ultimately whether or not D614G increases transmissibility remains unknown. No doubt those studies are in progress. Ideally these will be performed in multiple transmission models to confirm the findings.
The good news: at least in hamsters, this mutation didn't appear to confer any observable differences in pathogenicity. The virus may be mutating—because that's what RNA viruses do—but it's not becoming more virulent.
The second good news: serum from hamsters infected with D614 virus neutralized G614 virus in culture, suggesting that vaccines (all designed against D614 spike) will work against either variant.
My take home: while the jury's still out on whether this variant is more transmissible in the real world, it still can be neutralized by antibodies against all the vaccine candidates. It's not mutating into something more dangerous or pathogenic. It's behaving like a normal virus
Ultimately it doesn't matter whether D614G is more transmissible or not: the message to everyone is avoid getting EITHER variant of SARS-CoV-2.
Stay the course and stay safe, so that you can be protected against all known variants when a safe, effective vaccine is ready.