Read on Twitter
The UK variant may have evolved in just one person, infected with the Sars-CoV-2 virus for an unusually long time.
So what does this mean for the pandemic, and stopping future variants? A thread. https://www.wired.co.uk/article/chronic-infection-uk-coronavirus-variant
So what does this mean for the pandemic, and stopping future variants? A thread. https://www.wired.co.uk/article/chronic-infection-uk-coronavirus-variant
The emergence of the UK variant (B1.1.7) was unusual because it seemed to acquire a lot of genetic changes all in one go. Sars-CoV-2 usually acquires one or two changes to its genome per month, but when B1.1.7 was first spotted, in September, it had acquired 17 changes in one go.
There could be a few reasons for this, but the most likely – researchers think – is that the variant evolved over a long period of time in a person chronically infected with the virus.
Some people stay infected for extremely long periods. One man shed poliovirus for at least 28 years. Some people stay infected with norovirus for more than six months.
Usually this is because the person is immunocompromised – their immune system can't fully clear the virus.
Usually this is because the person is immunocompromised – their immune system can't fully clear the virus.
We know this happens with Covid-19. One man, a cancer patient, harboured replicating virus for at least 119 days. Another man sadly died after 102 days of illness. In Saint Petersburg, a 47-year-old woman was ill for more than four months. ( @LauringLab and @GuptaR_lab)
In all of these cases, the virus changed significantly over the course of the infection – in the last two, it picked up the same key mutation that B1.1.7 has.
Chronic infections create the perfect environment for virus evolution.
“The whole time, their immune system is effectively beating [the virus] up. So the virus has a chance to learn how to live with the human immune system,” is how @firefoxx66 put it.
“The whole time, their immune system is effectively beating [the virus] up. So the virus has a chance to learn how to live with the human immune system,” is how @firefoxx66 put it.
What does this mean for tackling the pandemic?
We have to do everything we can to stop transmission. Chronic infections are edge cases, but when you have hundreds of millions of infections, they will happen.
Social distancing, track and trace, face masks – all of that and more
We have to do everything we can to stop transmission. Chronic infections are edge cases, but when you have hundreds of millions of infections, they will happen.
Social distancing, track and trace, face masks – all of that and more
We need to get better at genomic sequencing across the world. The UK sequences about 10% of its positive tests, but in many countries we have very little idea how the Sars-CoV-2 genome is changing.
The more we sequence, the better we can get at understanding new variants.
The more we sequence, the better we can get at understanding new variants.
Lastly, we can do more identify long-term shedders and alter treatments so they are less likely to lead to mutations.
This is no substitute for getting transmission as low as possible. B1.1.7 has already gained new, worrying, mutations. The only way to stop it acquiring even more is to give it fewer people to infect.
Thanks to @lauring_lab, @GuptaR_lab, @firefoxx66, @jcbarret, @EvolveDotZoo who are all doing extremely important work on new variants and took some time out to chat with me https://www.wired.co.uk/article/chronic-infection-uk-coronavirus-variant
