What We Know About the New Coronavirus Variant

There’s still plenty of unknowns, but here’s a few takeaways

Andy Slavitt
Medium Coronavirus Blog
4 min readJan 5, 2021


Credit: National Institute of Allergy and Infectious Diseases, NIH

Here’s the best we know about the impact of the South African strain, and the impact on the vaccine from lots of conversations I’ve had with experts.

To begin with, we are back to assuming a modest and humble position that there’s a lot we don’t know, just like we were early on. When we are in the “there’s a lot we don’t know” stage, I like to air on the side of caution. Risking being wrong is no reason not to act. Acting wisely with the best we know can save the most lives.

What we know about the most significant variances is that they are more infectious. That’s why we noticed them. Important and subtle point I keep hearing: The virus is mutating in less visible and measurable ways that we can’t see as easily and therefore can’t address.

As we vaccinate more people, these other evolutionary mutations are likely to become more visible. But we have to deal with the ones in front of us first. The one first spotted in South Africa has mutated several things at once and there is more nervousness about the vaccines here.

Because we don’t know how much of the virus we missed, we could be seeing a jump in cases compared to no mutations (lowest line) anywhere from the green (we haven’t missed much) to blue (there is a lot more than we know).

So if you look at the curve on the right, the space under the curve between the colored lines and the low lines represents excess deaths from the mutation. It’s a big range — anywhere from 20,000 to 260,000 additional deaths — assuming our current projected rate of vaccinations.

There are many simplifying assumptions here but the magnitude is worth understanding.

Next question — why? Isn’t this not supposed to be more deadly? Think of the virus as being easier to attach to a cell. One way to think about it is if today it normally requires 1,000 particles to cause infectiousness, the new strain requires about 60% fewer or 400 particles.

If the virus spreads more easily, it will infect more high-risk people who will be in need of hospitalization. It also prolongs the spread as the graphs show. It’s fattening the curve not flattening it.

What about kids? Why is it impacting more kids? Kids aren’t actually more susceptible relative to others. They are more active. If the threshold is 60% lower, everyone is more susceptible. So more kids are just seeing a bigger jump.

Now to the most speculative topic. How will the vaccines respond?

There are labs around the world right now with assays of all the vaccines trying to answer that question. They are testing the sustained immune response but aren’t able to test T-cell response.

They require five weeks or so to get definitive answer on how effective the vaccines are, and I have data points that are too early to share. Too unreliable. So best to say we don’t know. But here’s my sense… My sense is that all the vaccines work on the new strain but not at the same rate. And that the vaccine platforms have different levels of effectiveness. But those calculations matter less than some of the important likely conclusions.

  1. If 15 minutes of exposure would cause an infection before, it is safest to assume that spending six minutes around the new strain could have the same effect. Again on the conservative principle.
  2. We should be more careful with kids. They should circulate less or will become vectors. Like mosquitos carrying a tropical disease. Of course they can become sick themselves this way. I’m not sure what I would say about schools besides wishing Trump had built testing up.
  3. We do need to assume that this is far more widespread than we know given how little priority we placed on sequencing. So I’m assuming it’s near me even though we don’t know. I took my son to a store today and went inside briefly. It was pretty empty. But I was 60% more nervous and tried to get out 60% faster while yelling at my son 60% louder through my mask. Zach thinks I’m 60% more annoying.
  4. There will be a sustained battle against Covid-19 that won’t be simple. Our vaccinations need to be good and efficiently delivered and likely continuously evolving. We will need to continually vaccinate in all likelihood.
  5. This raises additional questions — one vaccine for all before two for all, more efficient and different cutoffs. I’m going to stay out of that debate. Others with informed opinions are opining. It is clear we should look at everything.

When everything started I took plenty of criticism for suggesting we should assume this was going to be a public health disaster. I get it. Some on Twitter live to criticize. But human lives once lost are gone. And I for one will take the precautionary principle.

We will learn more. But given where we are right now, being smart, being honest, and adjusting along the way as we learn more is the best way to go. That way we can best meet every challenge.

(This is pulled and lightly edited from my Jan. 3 Twitter thread).