COVID-19 vaccine: at what cost?

By Zhuying Ser

With thousands of people dying, unemployment rising, and a global recession becoming more and more apparent, everyone is looking to one solution that will make all of the chaos go away: a vaccine for COVID-19. 

There are four main stages involved when developing a vaccine: the pre-clinical stage; human trials; mass manufacturing; then distribution to those that need it. In the pre-clinical phase, the drug is tested on human cells or lab animals to see if they effectively inhibit the effects of the disease. After the pre-clinical stage, the drug can move on to be tested on humans in the human trials stage. This stage is further divided into three phases, each phase progressing to a larger cross-section of the human population. Phase I focuses on figuring out whether the drug is safe whereas phase II highlights whether the drug works or not. Phase III is the longest and broadest step, with thousands of participants required. Participants at this phase are recruited to represent the whole human population, whether they are young or old, healthy or unhealthy. These people are then given either the vaccine or a placebo and then monitored for months or even years on how they respond when and if they catch the disease later on. After all of this testing, if the drug is found to be both effective and safe, it can then finally be manufactured by pharmaceutical companies and distributed around the world. This kind of development of a vaccine usually takes around 10 years to complete and sometimes even longer. However, there are ways to try shortening the time for a vaccine to become ready for distribution. 

Scientists such as Nir Eyal, Marc Lipsitch, and Peter G Smith suggest Human Challenge Studies as a solution. The human challenge study differs from regular drug development in that instead of waiting around for the participants to potentially become infected with the disease, healthy individuals are purposefully infected with the pathogen and the effects of the vaccine are monitored. By doing this, researchers can considerably reduce the time taken in phase III of the human trials (McKeever, 2020). Human challenge studies are not a new concept: they have been used before for many infectious diseases such as influenza, typhoid and the common cold. Previous research shows that human challenge studies saved up to three or four years of time which in return saved thousands of lives. So far, human challenge studies have not threatened lives and are deemed ethical for some diseases as the benefits for the human population significantly outweigh the small risks posed to a few individuals (Cohen, 2016).

However, SARS-CoV-2 is different to the other diseases that were tested in this way in that there is no effective treatment for the virus. This means that the risks for individuals who contract the disease are significantly higher, as they could become seriously ill or even die. This is one of the reasons why the World Health Organisation (WHO) deemed it unethical to carry out human challenge studies when the disease is virulent and there are no current treatments. However, in May 2020, WHO changed their guideline on vaccine development and issued that if researchers were confident enough that the benefits will outweigh the risks for the participants, Human Challenge Studies on healthy individuals without any predisposing conditions, could be a carried out. Another ethical issue with participants “autonomously authorising the risks” is that the long-term effects of both the virus and the vaccine will be close to unknown, substantially increasing personal risks (Eyal et al, 2020). 

With over 150 vaccines in development across the world and WHO coordinating collaborations between them, there is definite progress towards a COVID-19 vaccine. However, we may need it to come sooner. Even a few months could save thousands of lives and greatly reduce socioeconomic consequences. However, out of all of the institutions with potential vaccines, only one – the Jenner Institute at Oxford University – is seriously considering using human challenge trials. Most other institutes deemed this type of trial unethical (Matthews, 2020).

An additional problem with conducting human challenge studies for a coronavirus vaccine is that, since only healthy individuals in the age bracket of around 20 to 45 years of age will be tested, whether or not the vaccine will work and behave in the same way in people that are older or not healthy will not be guaranteed. On the other hand, an immediate goal of even 50% effective vaccines may be worth the risk as even imperfect vaccine could save numerous lives.

Although the ethics of human challenge studies to produce a vaccine for the corona virus is debatable, it is certainly heart-warming to know that tens of thousands of people from over 100 different countries, through an advocacy group, have already signed up to volunteer if trials were to begin.


Cohen, J. (2016) Studies that intentionally infect people with disease-causing bugs are on the rise. Available from:

Eyal, N., Lipsitch, M. & G Smith, P. (2020) Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure. Available from:

Matthews, D. (2020) How Exposing Healthy Volunteers to Covid-19 for Vaccine Testing Would Work. Available from:

McKeever, A. (2020) Dozens of COVID-19 vaccine are in development. Here the ones to follow. Available from:

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