Since the start of the pandemic last year, a handful of highly transmissible Covid-19 mutations have become ‘variants of concern’ for health officials around the world. The highly contagious Delta variant, first identified in 2020, has become the dominant variant worldwide – and now a sub-variant of Delta has been detected in numerous countries.
The sub-variant, known as AY.4.2, is mainly found in the UK and experts expect it to become dominant in the country within a few months.
Pharmaceutical Technology speaks with virologist Dr. Phillip Gould of Coventry University on the subvariant, Covid-19 vaccines, and whether the new antiviral molnupiravir will have the impact governments are hoping for.
Darcy Jimenez: What do we know so far about the Delta subvariant?
Philip Gould: New variants will continue to appear and evolve, and their ability to transmit and cause high infection rates will eventually lead to them becoming dominant within the population. Eventually all RNA viruses will mutate because of the way they replicate; most new variants will not be effective for transmitting, but the one in a billion version it produces, which can transmit better, will eventually adopt it in every population.
We see that in the different variants. Now we have the new Delta sub variant that is increasingly common in regions in the UK, and it will eventually be replaced. The key question is: how long will it take before that variant is replaced? And does the new variant cause a worse disease?
It is impossible to predict [a dominant variant], but you can try to reduce it by preventing its spread. The more people infected, the more likely a new variant will appear, so that’s why, for example, getting everyone around the world vaccinated is one of the most important things. It’s all well and good that the UK has high vaccination coverage and limits the number of people getting infected here, but if Covid is still spreading rapidly around the world, there’s a good chance a new variant will appear there.
DJ: How effective are the current vaccines against variants, including the new Delta subvariant? Will boosters be needed to protect them?
PG: You may have come across the term ‘plug-in’; the idea is that you can add any new sequence to [the vaccine]. The vaccines were first developed based on the circulating strains identified in Wuhan in late 2019, early 2020 – so immediately the scientists of the vaccine companies started using the genetic sequence of the strains’ S protein. What we’ve seen is that that sequence, that genetic code, has been mutated through the different variants.
What would be ideal – and very difficult logistically – is to be able to change the plug-in bit to that new variant, or a combination of both, as soon as a new variant appears. We’re not at that stage yet. The vaccine companies are doing a great job, but that product needs to be adapted – and I’m sure it is being done – to these new variants.
People who are double vaccinated still get infected, but hospital admissions in double vaccinated people are much lower, so the vaccine does provide protection. What’s brilliant is that these vaccines originally had very high efficacy – 95% for example, which is virtually unheard of, and certainly way above what was predicted. It’s brilliant, absolutely brilliant, that protection is there, but the technology does allow manufacturers to change their variant.
As for boosters, we don’t know how long the effects of the vaccine will last, and I think boosters are a great idea, especially for people whose immune systems are more compromised. But we need to spread vaccines all over the world. The British government has promised X, Y and Z, but they will deliver. The percentage in certain countries is less than 1% of people vaccinated – the UK reaches almost 90%, and that’s a big difference.
DJ: What measures do you think should be taken to prevent Covid-19 cases from increasing in winter and overwhelming hospitals?
PG: Looking at the UK alone, historically hospitals get saturated in the winter anyway, and that’s only going to be impacted again this year. We will see a big stretch in the NHS which will inevitably lead to the government having to reconsider what restrictions are put in place; plan A and plan B are quite loose compared to what we were used to before. I think it’s very difficult now, because people forget quite quickly what the consequences are.
There’s a good balance in the understanding that this virus will be here for a long time, and we just have to accept it, about how to mitigate the effects. I think our behavior has changed drastically; to me at work people don’t come to work with coughs and colds even though their lateral flow tests and PCR tests are negative. If they come back positive they will stay at home and I think the infrastructure will really support and stop that spread of infection.
If the new variants are more transmissible, which they appear to be, it will only take a few of these cases before areas see a higher infection rate. If you get that in a local hospital, which is already behind schedule, you’re going to have problems.
DJ: The new Covid-19 antiviral molnupiravir was recently approved in the UK. Do you think it will be the game changer it is claimed to be?
PG: I don’t think it’s a game-changer the way the vaccines are. Historically, antiviral drugs have not been hugely effective on their own. Where they’ve been successful has been against HIV, but that’s only because they’re used along with other antivirals. Because the mutation rate is high [in viruses], you add a selective pressure like a drug, and the virus will mutate and bypass that — so if you take an antiviral in isolation, what probably will happen, and what we’ve seen is the virus bypasses by mutation and becomes resistant is becoming .[Molnupiravir] has been repurposed, hence its speed. It was previously designed for other respiratory viruses. If we use the drug – which is great – drug resistance will occur, so more drugs have to be developed. It’s a constant evolutionary arms race between scientists and whatever causes the disease.
So yes, let’s use it. It is an additional way to prevent infection. If someone is vulnerable and someone in their household becomes infected with Covid, this could be a good treatment to give someone in those early stages, to avoid getting infected. There are a few other antivirals that will come on the market, Pfizer has one as well. So yeah, brilliant, but I don’t think it’s as big a game-changer as vaccines are. Prevention is much better than cure.