Variants of concern explained
SARS-CoV-2, the virus that causes Covid-19, is constantly changing. As it infects a person, it picks up small alterations to its genetic code.
The majority of these mutations do not lead to any significant change in the virus. Some, however, cause changes to the virus that allow it to infect and spread more effectively. These advantageous mutations become known as ‘variants of concern’. Writing for the Royal Society’s blog, Dr Katrina Lythgoe explains several key mutations and variants of concern that have developed since the virus was discovered in December 2019.
Early in its initial spread round Europe, SARS-CoV-2 picked up an important mutation to the spike protein that gives the molecule its distinctive shape. This mutation, which became known as the D614 mutation, made the virus more transmissible. Dr Lythgoe says that this development was a defining moment for scientists, as it showed how a single mutation in the virus’s genome can affect the course of the pandemic.
Further ‘variants of concern’ have developed throughout the course of the pandemic. Dr Lythgoe focuses on the B1.351 variant (originating in South Africa) and variant P.1 (originating in Brazil). Both of these variants contain mutations that appear to weaken the ability of antibodies to deal with the virus. Reasons why these variants have developed in the way they have are still not fully understood.
However, Dr Lythgoe cites the speed in which genetic sequencing is able to map new variants as important in staying ahead of the virus. Vaccine developers are also tweaking their vaccines rapidly as new mutations and variants emerge, decreasing the likelihood of a variant emerging that scientists are unable to target.
Read the full article:
- Dr Katrina Lythgoe, ‘How is COVID-19 evolving?’, The Royal Society, 29 March 2021
The Covid Infection Survey
The Covid-19 Infection Survey (CIS), run by the Office for National Statistics (ONS) and scientists at the University of Oxford, has been providing fortnightly data on the spread of the pandemic since April 2020. This blog post from the ONS team explores the mechanics of the survey in more detail, and takes a look at how the survey will develop over the coming months.
The deputy director of the CIS, Tina Thomas, looks back at the first year of the survey. Beginning with a pilot sample of 21,000 participants in England, the CIS now samples over 150,000 people per fortnight across England, Wales, Scotland and Northern Ireland. Data recorded include:
- detailed analysis of the characteristics and symptoms of those with Covid-19;
- how many people tested positive for antibodies; and
- from December 2020, how many cases were compatible with a new variant of the virus emerging in Kent.
Thomas then explains some of the next stages for the CIS. Focusing on the vaccination programme, Thomas identifies the roll–out of finger prick blood testing in a subsample of participants as a vital way of gathering data on different types of antibodies. Crucially, this will allow scientists to distinguish between antibodies generated through vaccination and antibodies generated through natural infection. This monthly blood testing will also shed light on how long antibodies remain effective against the virus, and will allow further study of the risks of re-infection after a vaccine has been administered.
Read the full article:
- Tina Thomas, ‘Mapping the next stage of the COVID-19 Infection Survey’, Office for National Statistics, 30 March 2021