Editor’s note: Two new strains of the coronavirus that cause COVID-19, called B.1.1.7 and B.1.351, have been found in the United Kingdom and South Africa and are considered more transmissible. In this interview, David Kennedy, a biologist studying the evolution of infectious diseases in Penn State, explains how these new strains differ, what “more transmissible” means, what they mean to the public, and whether the vaccines against them will be effective. .
What are the two new variants of the SARS CoV-2 virus?
There are actually a few different variants that appear that you have probably heard recently. Two of the most common things that people talk about and that they are most worried about are the B.1.1.7 and B.1.351 variants. They were first detected in the United Kingdom and South Africa. They appear to have been circulating at least since October, but this was only noticed in December. The concern about these variants is that they may have differences in how transmissible they are and how the immune system views them.
What does ‘more transferable’ mean when it comes to these variants?
The data suggest that both of these variants are more transferable. Most available data are especially for the British variant. It is still not clear how much more transmissible it is, but current estimates are that it is between 30% and 80% more transmissible than the original strains that were there.
How did scientists come to these numbers? When nails in cases in the UK caused concern, they followed up the virus during the nails out of the cases. They saw that there was this new variant. They look at the frequency of this variant further back in time and see that it increases in frequency over time. It was therefore very rare after very common. And based on the increase, they estimate that it was about 70% more transmissible than the original virus.
The second way they have determined that it is more transferable is through something called the ‘secondary attack rate’. What they do is that if they know someone is infected, they can see how many of their contacts have become infected. And so they can do it for people infected with the original strain of the virus, and they can do it for people infected with this new variant. What they saw was that people with this new variant were more likely to infect their contacts, and that the increase was about 30% to 40%. This therefore means that this new variant is more likely to be transmitted to other individuals.
How does a more transferable variant translate into risk? How does this affect people’s daily risk levels?
The first thing I have to say is that there is no evidence that the disease is worse because of these variants. So it does not seem to be more harmful now. But the concern is that more people will become infected, and thus more people will become ill overall.
But the reason it’s so worrying is that you’re twice the increase in portability. First, more people will be infected, so you are more likely to be with someone who is contagious. And secondly, the virus is more contagious, so every infected person is more likely to transmit it to you.
With that said, the basics of how we are supposed to live our lives and how we should control them are unchanged. The mitigation measures we have in place, things like social distance, wearing a mask, avoiding indoor shared spaces, reducing unnecessary risks, are still the best measures to try to control it. At least until we all have access to vaccines.
What does this new variant mean for vaccine effectiveness?
If we look at the smallpox vaccine, we have never seen resistance to it develop. It’s the same for measles, polio and most vaccinations we have. We never have to update them, and they just keep working.
But there are vaccinations where we need to update them because resistance has developed. And such a part of the concern about these new variants is that there may be resistance to the vaccines currently being developed.
The reason why people are worried is that many of the mutations in these new variants are in the place targeted by the vaccines, something called the peak protein. But just because we see changes in the protein of these variants does not necessarily mean that it will undermine the vaccine.
What researchers have seen is that one of the mutations that occur in the UK and South Africa variants has no effect on how our immune system sees the virus, so that’s good news. But another mutation found in the South African variant has an impact on the way our immune response sees the virus.
We have learned that if you are taking blood serum from someone who was previously infected with the old version of the virus, and you are trying to use the serum to stop the virus containing this new mutation, you will need a higher concentration of the blood serum neutralizes the virus. This means that there is a difference in the way our immune system sees the virus. This does not necessarily mean that the vaccine will be less effective. But it is definitely something that needs to be studied more.
These are two of the mutations. There are many more mutations in these variants, which scientists need to study.
The summary here is that at least one of the mutations seems to be relevant, but there is no good evidence to suggest that the vaccines will not be effective. Vaccines tend to be strong against evolutionary change. And so is my hope and my expectation that the vaccine protection will be strong.