[ad_1]
The conversation via AP – A new variant of SARS-CoV-2 is spreading rapidly in the UK, with more than 1,400 cases since September. SARS-CoV-2, the virus that causes COVID-19, usually accumulates mutations slowly over time, but this new variant has accumulated many mutations quickly.
If this new version of the virus is here to stay, as it appears to be, what does it mean? Will this new version of the virus replace the old one? Will it be easier to catch? And above all, will current vaccines still be effective?
This interests me because I am an evolutionary microbiologist who studies the link between the transmission and evolution of infectious diseases. In particular, I spend a lot of time examining the effects of vaccines on the evolution of pathogens and the effects of the evolution of pathogens on the impact of vaccines.
Receive the daily edition of The Times of Israel by email and never miss our best articles Sign up for free
What is the new SARS-CoV-2 mutant that has emerged?
The new version of SARS-CoV-2 – called the B.1.1.7 lineage – is spreading across the UK and beyond. The differences between the old and the new virus include 23 mutations in the virus’s genetic code that altered four viral proteins.
Eight of these 23 mutations affect the spike protein. This is important because the spike protein allows the virus to enter human cells, and it is a key target in our immune response, both to fight the virus during infection and to protect us from disease afterwards. vaccination with the Pfizer and Moderna vaccines.
If the changes to the spike protein help the virus to enter human cells more easily, then the virus could be transmitted more easily from person to person.
These mutations can also alter the way the host’s immune system fights the virus, potentially reducing the effectiveness of current vaccines.
A nurse in a COVID-19 unit in Mission Viejo, Calif., December 21, 2020 (AP Photo / Jae C. Hong)
How is this new version of SARS-CoV-2 different?
Samples of the new virus isolated from patients suggest that this variant has increased in relative frequency over the past three months.
The increase in frequency is concerning, as it suggests – but does not prove – that B.1.1.7 isolates of SARS-CoV-2 are more transmissible than the original virus. Some have estimated that the new virus could be up to 70% more transmissible than the old virus. Although these estimates are consistent with the data, it is far too early to draw a firm conclusion.
If this increased transmissibility is confirmed, it could be due to mutations in the spike protein allowing it to bind more tightly to the ACE2 receptor, which provides a gateway for the virus to enter human cells.
But it could also be due to one of the other changes to the virus.
Is it more dangerous? If yes, why?
If the new version, B.1.1.7, is indeed more transmissible than the old virus, it will be more dangerous in that it will make more people sick.
However, I do not know of any strong evidence that there is a difference in the severity of the disease caused by the new version of this virus compared to the old one. That said, with so few known cases, it may still be too early to tell.
A COVID-19 is treated by nurses in an emergency room in Mission Viejo, Calif., December 21, 2020 (AP Photo / Jae C. Hong)
Will Pfizer and Moderna vaccines still be effective against this new strain?
The Pfizer and Moderna vaccines work by training our immune systems to recognize a specific version of the viral spike protein. The version of the spike protein used by the vaccines was designed to match that of the old virus, not that of the B.1.1.7 virus. This means that vaccines could become less effective than expected if this new virus spread widely.
Vaccine-virus mismatch is a continuing challenge for scientists tasked with developing the seasonal flu vaccine. But even with a virus-vaccine mismatch, the influenza vaccine reduces the likelihood and severity of illness.
So the question is not whether the vaccines will be effective, but rather how effective they will be. The severity of the mismatch is significant, but the only way to determine its impact in this case is through a scientific study, and to my knowledge, no data on this has yet been collected. In other words, it is too early to say if and how this new variant will influence the overall effectiveness of the Pfizer and Moderna vaccines.
Should people still get the new mRNA vaccine?
The emergence of this new B.1.1.7 makes it even more important that people get vaccinated as soon as possible.
If this new version is more transmissible or if the vaccine is less effective due to virus-vaccine mismatch, more people will need to be vaccinated to gain herd immunity and control this disease.
Additionally, we now have evidence that the SARS-CoV-2 spike protein can change dramatically in a short period of time, and therefore bringing the virus under control is essential to prevent it from evolving further and completely undermining efforts. vaccination.
[ad_2]
Source link
