Why vaccines can't be launched overnight

Under normal circumstances, the development of new vaccines and treatments could take 10-20 years

While the quest for developing vaccines for Covid-19 is on at pandemic speed, there has been widespread speculation that vaccines may come out in the market soon. However, scientists such as the UK’s chief scientific adviser, Sir Patrick Vallance, and his US counterpart, Anthony Fauci, keep repeating that it won’t happen before 12 to 18 months. Also, in late February, the World Health Organization said that it wasn’t expecting a vaccine in less than 18 months. So the confusion continues.

Certainly, a drug cannot be manufactured and prescribed as soon as a potential molecule is identified in the lab. Thereafter, some preliminary animal experiments are customary. And that’s not enough — one needs to carry out a rigorous experimental testing procedure on human beings, called “clinical trials”, to judge both its safety and effectiveness. A clinical trial has four phases, the first three phases are essential at the drug development stage. Phase I is the study of safety, and is usually carried out on human volunteers — actual patients are not needed at this phase.

Various doses of a potential treatment are applied to the volunteers according to a pre-fixed schedule, and the objective is to find the acceptable dose levels which would not have serious side-effects. These doses of the treatment are then transferred for phase II trial, which is a study of safety and efficacy together. Hence, actual patients are required at this phase onward. Some potential doses of the drug are studied in phase II, and only a few among them, that are both effective and more or less safe, are forwarded for a phase III study. Phase III is concerned about effectiveness only, usually in comparison to some existing treatment (if any) or some similar-looking treatment having no effect (called placebo). Such a trial is called “controlled”. And the trial should be “randomised” as well, that is, any patient within a phase III trial is typically assigned to either of the competing treatments at random, and neither the patient nor the doctor knows which treatment is given to whom. 

If, after the three phases, the concerned organisation finds that the treatment is safe as well as effective for the disease under consideration, they send the study report to the regulatory agency of the concerned country. If the regulatory agency is convinced, it would permit its marketing and en masse usage. Phase IV is about post-marketing surveillance.

During the past two decades, scientists and the phrmaceutical industry got engaged to respond urgently to epidemics like SARS, H1N1 influenza, Ebola, MERS, Zika, and now Covid-19. An H1N1 influenza vaccine was not available before the pandemic peaked in the northern hemisphere, and SARS and Zika epidemics ended before vaccine development was complete. In fact, the vaccines history of other coronavirus diseases are not quite encouraging — there is no protective vaccine for SARS that has been shown to be both safe and effective, and there is also no proven vaccine against MERS.

However, there are more than 100 ongoing attempts worldwide by pharmaceutical companies and government and university labs for finding vaccines for Covid-19. A detailed list of “Covid-19 Treatment and Vaccine Tracker” up to July 10 is available on https://covid-19tracker.milkeninstitute.org/#vaccines_intro, which contains an aggregation of publicly available information of 192 attempts for finding a vaccine from validated sources. In fact, most of the trials are still at the pre-clinical stage, while some have entered the clinical stage. Under normal circumstances, the development of new vaccines and treatments may even take 10-20 years. However, dozens of pharmaceutical companies all over the world are now racing to compress this timeline; they are ratcheting up their efforts to create new vaccines with accelerated schedules — with the support of non profit organisations, government agencies and regulatory authorities.

While there can be no shortcuts to establishing safety and efficacy, some companies are adopting potentially risky and controversial steps — in a desperate bid to make Covid-19 vaccines. The Oslo-based not-for-profit Coalition for Epidemic Preparedness Innovations (CEPI), for example, laid out the plan for the implementation of a “pandemic paradigm” model, which might conduct the animal trial and phase I in parallel.

In February, WHO published a draft protocol for phases II and III that would test a number of candidates simultaneously, in multi-country trials according to standardised criteria. Conducting clinical trials during a pandemic might have additional challenges. It is well-known that the success rate of obtaining approval from phase I to successful phase III trials is not too high for any vaccine candidate, and the CEPI indicated that a potential success rate for a Covid-19 vaccine might be only 10 per cent. But, with more than 100 ongoing trials having much more candidate vaccines, some useful vaccines may certainly come out!

And then, if a vaccine comes out, every country has to take its own call on using it, according to its own health protocol and jurisdiction. And, how and when billions of doses of the vaccine would be manufactured, how that would be distributed and used, what would be the cost of a vaccine, and who would bear that cost for vaccination of billions of people across different countries — none of this is clear.

Overall, if “having a vaccine” means a vaccine will be available for en masse use, 12 to 18 months is probably a reasonable time-frame to assume, and thus in all likelihood, a Covid-19 vaccine might not come out before the end of the current pandemic. Even after a Covid-19 vaccine is developed and deployed, the current coronavirus will likely remain for years to come, and may eventually, become endemic like HIV, measles, chickenpox, and four other endemic coronaviruses that are present, causing the common cold. And nobody knows how long — a few months or years — a vaccine will be able to protect from Covid-19.

Social distancing, however, may be the best way out, for the time being.

The author is professor of Statistics, Indian Statistical Institute, Kolkata