According to the latest list of the World Health Organization (WHO), at least 165 vaccines for the novel coronavirus were being developed across the world. There are possibly more. As Dr Davinder Gill, former CEO of Hilleman Laboratories, puts it, the actual number would probably be three times the number listed by WHO.
Those listed have all entered at least the pre-clinical trials stage. Some are in the final stage of human trials, possibly only a few months away from hitting the market (a Russian vaccine promises to be ready in weeks), while many others are just getting into animal trials, and are perhaps a couple of years away from becoming ready.
But why are so many vaccines being developed all at the same time? Here are some possible answers:
Success rate is always low
Vaccine development is a complex, time-consuming, resource-intensive process, and the chances of success are extremely low.
Of every 100 candidates that are considered in laboratories, barely 20 make it to the pre-clinical trial stage. This means almost 80% of the candidates are not even considered suitable to be tried on animals. Then, not more than five of the original lot are approved for human trials, and out of these, not more than one or two stand a chance of being approved for public use.
In the current context, the 165 candidates listed in the WHO survey have all reached at least the pre-clinical trial phase. And, at least 23 of them are in human trials. Not all of these will be successful.
Though we are all being given to understand that it was only a matter of a few months before some of the leading candidates, like that being developed by Oxford University, would be available in the market, the reality is quite different. Even those that are in the final stages of human trials, with encouraging results from previous stages, are not guaranteed to succeed.
Phase-III trials, in which the candidate vaccine is tested for its ability to prevent infection in humans in real-life situations (outside of laboratory conditions), are the toughest part of the trial. Countries that have robust regulatory systems are unlikely to lower their bar just because of the current emergency. The effectiveness of vaccine in phase-III trials is crucial.
In the end, we are not staring at a possibility of hundreds of coronavirus vaccines. Even if only five or six succeed, that would be considered a very good success rate.
Multiple vaccines are needed
Considering that everyone would want to get their hands on a vaccine as quickly as possible, one vaccine is unlikely to meet the immediate global demand. There are already indications that some countries may corner a bulk of the new vaccines, leaving others to wait for them to become available at a later date. The US, for example, has entered into billion-dollar agreements with multiple leading contenders, and booked hundreds of millions of doses in advance. This could potentially restrict access for other countries, especially in the developing and poor world.
That is why several countries have started their own initiatives at developing a vaccine. Countries like Egypt, Thailand, Nigeria, Argentina, which are not known for vaccine research, are all in the race. Even if they are a little late, if successful, they would have control over production and supply.
“Having a diversity of candidates reduces the possibility of bullying by sectors within a country or by… countries against one another because there are more vaccines with more different distribution channels,” Marc Lipsitch, professor in the Department of Epidemiology at the Harvard T H Chan School of Public Health, said at a symposium last week.
There is another reason why multiple vaccines help. There is no guarantee that the first one would be the most effective. These vaccines are being developed in haste, and there is every likelihood that the ones that come later are able to learn from the experiences of the earlier ones, and make modifications to become more effective.
📣 Express Explained is now on Telegram. Click here to join our channel (@ieexplained) and stay updated with the latest
New technologies being tried
As they race against time, research groups around the world are testing several cutting-edge technologies in vaccine development, some of which have never succeeded in delivering a final product.
“Some of these are bleeding-edge technology. They’re the newest of the new,” said Gill.
For example, a DNA-based or RNA-based approach to produce a vaccine has not succeeded till now. But these approaches are being tried out to develop a coronavirus vaccine, because they are potentially quicker and easier to make.
In this approach, the genetic material of the virus (either DNA or RNA; and RNA in case of the coronavirus that causes Covid-19) is injected inside the body to trigger an immune response. In traditional approaches, which have succeeded in the past, scientists inject weakened live virus, or a dead virus, or a key protein of the virus to trigger an immune response.
“Before anyone could grow the virus in tissue culture, there were sections of industry and academia preparing a vaccine using newer technologies like nucleic acid-based platforms,” said Dr Vineeta Bal, an immunologist and visiting professor, at IISER, Pune. “Everybody is trying different approaches and some are seeing positive developments. Like Moderna (whose RNA-based candidate is in phase-III trials)… this is the first time that this kind of vaccine has reached the stage it has reached.”
The deployment of these newer technologies has increased the number of candidates. Some researchers are in the race for the learning experience as well. “In this mix of hundreds of companies, some, of course, are seeing this as an opportunity to build the capacity, raise capital and get their name out there,” said Gill.
Funds are available
Vaccine development is a very costly endeavour, requiring hundreds of millions of dollars. In normal times, only big pharmaceutical giants with deep pockets and risk appetite, or institutions with large research grants get into vaccine development.
Now, from governments to donor agencies to multinational corporations to international health initiatives, all have opened their purse strings for a coronavirus vaccine. Every candidate that shows promise in the laboratories is being backed.
Bal offers an interesting perspective. “The practice that has been observed over the years is that, if developed countries are affected, technological development for a solution is often fast-tracked. Here, you have countries in the West that are affected… By comparison, if you look at the development of vaccines for diseases of developing countries like TB and malaria, which have been around for much longer, there isn’t the same level of enthusiasm,” Bal said.
Commercial interests are also playing a role. “You have to remember that the chances of this virus spreading are much higher than other coronaviruses. This gives not only a larger market to vaccine companies, but also encourages them to enter the space because of the kind of countries that are impacted,” said Bal.
Don’t miss from Explained | WHO sees no silver bullet vaccine
And Gill said: “I think the potential is actually huge. If you make the assumption that the vaccine works across (all age groups and comorbidities)… you’re looking at an unprecedented, blockbuster, multi-billion-dollar potential for this product.”
📣 The Indian Express is now on Telegram. Click here to join our channel (@indianexpress) and stay updated with the latest headlines