Every week, a group of epidemiologists from the north-eastern United States join a call to discuss the latest Covid-19 variant reports.
William Hanage is an epidemiologist at the Harvard Chan School of Public Health. It used to be that we had Alpha coming up here. But now it is Delta.
It would be easy to assume that the once rapid evolution of the virus has been replaced by a state of quiescence since it was first detected in India in December 2020. According to the World Health Organization, almost all of the Covid-19 genomic sequence reported to public databases are now Delta.
New strains have continued to emerge. The Delta Plus variant in the UK, which scientists estimate to be 10-15% more transmissible, are almost identical to the Delta variant, apart from the odd minor variation here and there. Hanage referred to them as Delta's grandchildren.
He says there have been a few Delta Pluses. Delta Plus is code for whatever people are getting their knickers in a twist about at the moment, I said in a recent radio interview. It is not more transmissible.
Hanage and his colleagues try to predict what will happen next by scanning databases such as Pangolin and Nextstrain each week. Is Delta really Covid-19's end game or is it something more ominous to come? No one is certain of the answer to the question.
It is certain that there will be another significant variant in the next two years.
Prof Gupta is from the University of Cambridge.
One possibility is that after the initial dramatic jumps in its genetic sequence, which gave rise to first Alpha, then Delta, then finally to sars-coV-2 will slowly and steadily evolve, eventually moving beyond the reach of the current vaccines, but only over the course of many years. Scientists are careful to point out that their predictions are mostly speculation, but some think this is the most likely outcome.
Francois Balloux, director of the University College London Genetics Institute, says he expects the evolution of the virus to be antigenic drift. It takes about 10 years for a coronaviruses to accumulate enough changes not to be recognised by the blood.
The chance of dangerous variant occurring increases with high levels of the virus. William Hanage of Harvard University says that all of the variants have emerged in countries with high transmission. Dominic Lipinski is pictured.
The alternative is the sudden appearance of a completely new strain, with game-changing transmissibility, virulence or immune-evasive properties. The professor of clinical microbiology at the University of Cambridge says he is 80% sure that another one will emerge from these strains. The question is when.
Gupta says that there is a Delta epidemic at the moment. The kind of thing I am talking about is relatively weak compared to the new Delta Plus variant. I don't think it's a big deal that it has two Delta strains in it, and it hasn't taken off in other countries. It is certain that there will be another significant variant in the next two years and it will compete with Delta.
There are many ways in which this could happen.
Will there be a super variant?
In the last half of 2020, epidemiologists began to observe signs of a phenomenon known as viral recombination, in which different versions of sars-coV-2 exchanged mutations and formed a new strain.
Recombination is a feasible source of a new super variant, particularly in parts of the world where large numbers of the population are unvaccinated and viral strains can circulate freely. He says that this is less likely now that Delta is the key virus. We don't know what's going on in large swaths of the planet. It is a real possibility.
It is possible that more complex mutations can evolve in the future.
The Weizmann Institute of Science has a professor named Prof.
The second is a series of major changes that can result in a greatly enhanced version of Delta. There is still a lot of scope for this to happen. The professor of biomolecular sciences at the Weizmann Institute of Science in Israel says that the virus has huge potential to evolve in the future. More complex mutations can evolve with simultaneous changes at more than one position.
Concerns have arisen that the use of new antiviral pills, such as molnupiravir, could contribute to this by encouraging the evolution of sars-coV-2. The virus can no longer reproduce because of the interference with it's ability to replicate. If any of the viral strains survive and spread to others, it could theoretically spur the rise of new strains. It is not enough of a concern to deny severely ill patients a potentially life-saving drug.
The UK has a persistently high infection rate due to the ability of Delta to transmit between vaccine recipients. The more infections there are per day, the more likely someone is to get it and be immune-suppressed. They have a partial vaccine response and the virus learns to evade them and then they get the infection over a number of days.
Gupta published a paper earlier this year that showed that this could happen in severely ill patients who had been given convalescent blood. Their immune system was unable to clear the virus, so it learned to modify itself. It has been speculated that the widespread use of convalescent plasma was the cause of the emergence of variant.
He says that a lot of plasma was used and that it was possible that it was one of the drivers for the variant. In Brazil, India, the UK, and the US, it was used a lot.
The arms race is vaccine-variant.
Epidemiologists are trying to figure out what a new variant might look like. The major changes in the virus have increased its transmissibility. The Delta variant had an impact because it grows quickly within human cells before the immune system kicks into gear. People with Delta carry more viral particles in their noses than people with the original strain, and they develop symptoms two to three days sooner.
Natural selection is to blame. Different copies of the virus are being created all the time, but the ones that have survived and become more dominant are the ones that are more capable of infecting new people. In countries such as the UK, where the unvaccinated proportion of the population is decreasing, this could change. The next super variant is likely to be able to evade at least some parts of the immune response because of the sidestep antibodies that are likely to become more dominant.
There are concerns that the way the drug works will cause new changes. Most scientists don't think these will be harmful. The picture is of Merck & Co Inc.
Hanage says the strains of the virus that end up surviving and becoming dominant vary depending on which stage of the epidemic you are in. It has been more important for the virus to be transmitted into the remaining pool of people who have not been exposed to it. That is expected to change soon.
It is not all bad news. Because the Covid-19 vaccines are designed with viral evolution in mind, epidemiologists do not expect any new super variant to render them useless and so it would be extremely unlikely to lead to large serious outbreaks, such as those of the past two years.
There is a second generation of Covid-19 vaccines. Novavax is hoping to get regulatory approval for its jabs in the next couple of months, while many more vaccines are expected to come on the market between now and 2023. The platforms are taking their own steps to fight future variants.
You want to limit the number of chances the virus has to roll the dice.
William Hanage is an epidemiologist.
The executive vice-president and head of R&D at US pharmaceutical company Gritstone said that companies are trying to neutralise existing strains of Sars-CoV-2 by using a second-generation Covid-19 vaccine.
epidemiologists believe that relying on vaccines alone is not enough. Even though we are trying to find a way to live with Covid-19 in the UK, there should still be some restrictions in place to limit the spread of the virus.
Gupta says that it is better to prevent new infections at the moment because of the high case numbers. We shouldn't be wandering around in crowded places, in buildings without masks, even though it's hard to do. India, the UK, and Brazil are countries with very high, uncontrollable transmission. There is a reason why we haven't heard of a South Korean variant.
Many of his colleagues agree with it. Hanage says that you want to limit the number of opportunities that the virus gets to roll the dice. Natural selection is the most creative force that we know of when it comes to solving problems. It is amazing. You would never bet against it. The virus is expected to keep evolving.
