Vineet Menachery: The quickest answer at this point is: We don’t know yet. The mutations that we think about are twofold: There are mutations that allow the virus to replicate or transmit better. These are worrisome because obviously that just changes how fast this virus can spread. And that’s one of the concerns for these variants. There’s the U.K. variant. There’s a South African variant. And, most recently, there’s a variant in Japan that’s been traced back to Brazil. Each of these have a mutation at a position in the spike protein that are associated with, potentially, an increase in transmission.
Wells: Can you help me visualize it? It’s like the spike is spikier and therefore stickier, or something?
Menachery: The analogy I would make is that it’s like a key. And the spike protein has to fit to its key. Now you can think about a key in a lot of different ways, but the better that key fits, the more efficient and transmissible the virus is going to be. These new variants may actually fit that key better. And that allows the virus to replicate or transmit a little bit better than the previous versions. And that’s what’s concerning.
Wells: So this particular mutation wouldn’t mean that it hangs longer in the air or that it is better at sticking to your skin or something. It just means that, once it is in your body, it is better at actually latching on to the cells that it needs to infect you. It’s not actually that it’s easier to get into your body. It just is more likely to infect you once it’s inside.
Menachery: Yeah, I think it gets back to efficiency. Now, we don’t know anything for sure, but the barriers that are in place [such as] masking and social distancing will still be effective against this. The virus hasn’t changed fundamentally. It’s a small difference in a molecular aspect of the virus that gives it a little bit of an advantage. We think, based on the math, that it does have an advantage over the original, but we don’t know the scale at which it has an advantage. Is it 10 times worse or is it two times worse?
Both viruses, the original and this version, are pretty transmissible. And so if it’s two times worse, you may not be able to see the difference. If it’s 10 times worse, you’ll see that in terms of how quickly the virus spreads.
Wells: How do we figure that out?
Menachery: There are a bunch of different ways, and none of them are particularly great. There are experimental ways. Scientists here, and around the world probably, will take the different variants and put them into animals in direct competition. We’ll take the original and the new variant, mix them together, and put them in animals to see how well they transmit [and] how well they replicate.
Wells: Is that what you’re doing now?
Menachery: People in our group are doing that experiment as we speak.
