Episode #69 - COVID 19 : Tracking variants

22 March 2022 | Science conversation

Vismita Gupta-Smith

How does WHO track the variants of SARS-CoV-2, the virus that causes COVID-19? What are the challenges on the ground to tracking these variants, and how many variants are we tracking at this time? Hello and welcome to Science in 5. I'm Vismita  Gupta-Smith. We are talking to Dr Maria Van Kerkhove today. Welcome, Maria. Let's start, Maria, with how does WHO track the variants of SARS-CoV-2?

Dr Maria Van Kerkhove

It all starts with surveillance, making sure that we have really strong surveillance and testing around the world so we know where the virus is circulating. We know where it is spreading most intensively. And that testing needs to be supported by sequencing. Sequencing has expanded dramatically over the last couple of years, and this really helps us to track how the virus is changing. It's natural for viruses to change. The more the virus circulates, the more opportunities it has to change. So strong surveillance, strong testing, including strong sequencing, helps WHO with scientists around the world to look at those changes and determine which of those changes is important and why.

Vismita Gupta-Smith

So, Maria, since WHO is tracking the variants across the globe, tell us about the challenges that countries face and WHO faces while tracking the variants.

Dr Maria Van Kerkhove

So what is really difficult right now is as we are in the third year of this pandemic, it's really important that we maintain and in fact, enhance the surveillance systems that are on the ground. Now, countries are facing many challenges, COVID-19, as well as many other challenges that they have to deal with, other diseases. And so keeping up with surveillance, keeping up with testing and making sure that we have good tracking of this virus in at risk populations, people who are over the age of 60, people with underlying conditions, immunocompromised patients, to ensure that we are really understanding how the virus is spreading, where the virus is spreading is really critical. And to maintain that on the ground in the third year is quite difficult. But it is fundamental to the control strategy of COVID-19. Not only do we need to improve vaccine access, as you hear us talk about a lot, we also need to maintain public health services like surveillance and testing and sequencing. And this is critical for us to be able to determine how this virus is changing and importantly, what that means for us in terms of our counter-measures, looking at public health and social measures, looking at the use of antivirals and looking at different therapeutics, as well as ensuring that the COVID-19 vaccines remain effective. And I just want to highlight that the COVID 19 vaccines remain incredibly effective at preventing severe disease and death, including against the latest variant of concern, Omicron.

Vismita Gupta-Smith

So let's come now, Maria, to the variants that WHO is currently tracking.

Dr Maria Van Kerkhove

WHO is working with surveillance officers, public health officers, experts around the world to track this virus. We work with our technical advisory group for virus evolution to assess each of the variants and the mutations that are being detected. There are five variants of concern that WHO has classified as variants of concern at a global level. The latest is Omicron and in fact, we are following several sub lineages of Omicron. You've heard us talk about BA.1 And BA.2 There are other sub lineages that are circulating as well. So we work with experts around the world to look at the characteristics of the variants of concern. Are they more transmissible. And Omicron is more transmissible. In fact, a BA.2, of the sub lineages, is even more transmissible than B.A.1. We're also looking at severity and looking at are these variants of concern causing more or less severe disease? Now, we do know that Omicron is less severe compared to Delta, the other variant of concern that was circulating. But Omicron has now replaced Delta worldwide and it is not more, BA.2 is not more severe than BA.1, as I mentioned. But we're also looking at antivirals, we're looking at vaccines. And again, our vaccines remain incredibly effective at preventing severe disease and death, including against both of the sub lineages of BA.1 and BA.2

Vismita Gupta-Smith

Thank you, Maria. That was Science in 5 today. Until next time then. Stay safe, stay healthy and stick with science.