Omicron represents a new kind of epidemic: we must keep up | Emma thomson

SSince Omicron first emerged in late November, teams of scientists in the UK and beyond have been quick to grasp it. The results so far suggest that this new variant is producing a very different epidemic, which may mean that our approach must change as well.

Omicron immediately caused concern in the scientific community because it had 50 mutations compared to the original virus, many of which were known to produce significant changes in other variants. These focused on the spike protein, which sits on top of the virus particle and acts as the key to allowing it to enter human cells.

With other scientists from the MRC-University of Glasgow Center for Virus Research (CVR), I worked on A study suggesting that such a large change in beak structure will likely affect the protection we get from vaccines. We (and others) found that two doses of the AstraZeneca, Pfizer, and Moderna vaccines were significantly less effective against Omicron than other variants. This could partly explain why it is more transmissible than some other variants, given that all of our licensed vaccines to date are based on increasing immunity to the spike protein of the first variant of the virus that emerged in Wuhan in December 2019.

However, the response to three vaccines improved markedly. So the UK’s strategy of increasing booster deployment after the Omicron discovery was a good one and will have had a major impact on the number of serious cases presenting in hospitals in the coming weeks. Unfortunately this will not be enough to keep the NHS from coming under heavy pressure as hospitalizations and deaths are not yet fully decoupled from the large number of cases we are seeing in the UK. There is also the added pressure of staff shortages as a result of isolation after infection or exposure to infection. Meanwhile, older people or those with underlying health problems are at higher risk for serious illness.

Those spike protein changes don’t just affect Omicron’s response to vaccines. An unexpected finding in our study and another study from Imperial College London was that Omicron has fundamentally changed the way it enters the cells of the human body. Early reports also suggest that Omicron may cause a slightly less severe illness, which may be related to this change in the life cycle of the virus.

We found that while the above variants enter human cells by fusing with the cell membrane, which can cause severe disease by allowing transmission of the virus from cell to cell, Omicron is enveloped by the cell membrane within a capsule that is then injected into the cell membrane. cell. It has to escape from this capsule with the help of different proteins in the cell called cathepsins before it can divide and then infect other cells.

These findings have now been confirmed by researchers from Imperial College London, who also showed that Omicron can preferentially infect cells in the nose and is less likely to infect lung cells. Additional research will help us understand whether we should update our measures to prevent respiratory transmission of the virus as a result.

The best way to optimize our immunity against this new variant would likely be vaccines targeting Omicron (and other variants that have yet to evolve). These would have to be tested in clinical trials and can be reserved for those most at risk given the cost and speed required to implement them. It is important to note that the finding that three doses of vaccine is much higher than two doses has given us time.

The emergence of new variants, which is likely to continue, means that Covid requires us to be nimble in our research and response to the virus, whatever form it takes in the future.