What you need to know about the new variants of COVID-19

Editor’s note: Two new strains of the coronavirus that causes COVID-19 called B.1.1.7 and B.1.351 have been discovered in the UK and South Africa and are believed to be more transmissible. In this interview, David Kennedy, a biologist who studies the evolution of infectious diseases at Penn State, explains how these new strains are different, what “more transmissible” means, what it means to the public, and whether vaccines will be effective against them. .

What are the two new variants of the SARS CoV-2 virus?

There are actually a few different variations emerging that you have probably heard about recently. The B.1.1.7 and B.1.351 variants are some of the most common that people talk about and are most concerned about. They were first detected in the UK and South Africa. It seems they have been around since at least October but weren’t noticed until December. The concern about these variants is that they might have differences in how transmissible they are and how the immune system sees them.

What does “more transmissible” mean when it comes to these variants?

The data suggests that these two variants are more transmissible. Most of the data available relates in particular to the British variant. It is still not clear exactly how much more transmissible it is, but current estimates are that it is somewhere between 30% and 80% more transmissible than the original strains that were there.

How did scientists arrive at these numbers? When the spikes in UK cases raised concerns, they sequenced the virus from the cases during the spikes. They saw that there was this new variant. They looked at the frequency of this variant further in time and saw that it increased in frequency over time. So it went from very rare to very common. And based on the rate of increase, they estimate that it was about 70% more transmissible than the original virus.

The second way they determined that it was more transmissible is by using what is called the “secondary attack rate”. What they do is if they know a person is infected they can look and see how many of their contacts have been 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 who had this new variant were more likely to infect their contacts, and that increase was around 30% to 40%. So this means that this new variant is more likely to be passed on to other people.

How does a more transmissible 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 severity of the disease increases due to these variants. So it doesn’t appear to be more harmful now. But the problem is, more people are going to get infected, and therefore in total more people are going to get sick.

But the reason this is so concerning is that you are struck twice by the increase in transmissibility. First, more people will be infected, so it is more likely that you will interact with someone who is contagious. And second, the virus is more infectious, so everyone who is infected is more likely to pass it on to you.

Having said that, the basics of how we are supposed to live our lives and how we are supposed to control it are essentially unchanged. The mitigation measures we have in place, such as social distancing, wearing a mask, avoiding shared spaces indoors, reducing unnecessary risk, are still the best measures we must try. to control this. At least until we all have access to vaccines.

What does this new variant mean for the effectiveness of vaccines?

If we look at the smallpox vaccine, we’ve never seen resistance develop into it. It’s the same with measles, polio, and most of the vaccines we have. We never need to update them and they keep working.

But there have been vaccines for which we have to update them because resistance has evolved. And so part of the concern about these newer variants is that there could be an evolution in resistance to the vaccines that are currently under development.

The reason people worry is that a lot of the mutations in these newer variants are found in the site targeted by the vaccines, which is called the spike protein. But just because we’re seeing changes in the spike protein of these variants doesn’t mean it will harm the vaccine.

What the researchers saw was that any of the mutations found on the UK and South Africa variants didn’t appear to have an effect on how our immune system views the virus, c is therefore good news. But another mutation found on the South African variant appears to have an impact on how our immune response views the virus.

We have learned that if you take blood serum from someone who was previously infected with the old version of the virus, and you try to use that serum to stop the virus containing this new mutation, you need to a higher concentration of blood serum to neutralize 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 certainly something that needs to be studied further.

These are two of the mutations. There are many other mutations in these variants that scientists need to continue to study.

The summary here is that at least one of the mutations appears to be relevant, but there is no good evidence to suggest that the vaccines will not be effective. Vaccines tend to resist evolutionary changes. And so my hope and expectation is that vaccine protection will be strong.