Despite unprecedented efforts in finding the cure for coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), no one can accurately predict the exact timing for the availability of a safer and efficacious vaccine. Even if a suitable candidate vaccine is developed, there is no setup to mass manufacture to fulfil the demands of existing needs in the world. Several dozen companies are involved in the development of vaccines and almost ten different methodologies are being utilised; which one will be the choice also needs to be decided. All these are questions lingering in the hearts and minds of governments, scientists, companies investing in vaccine development and every other stakeholder. On top of this, coronaviruses abrogate preexisting natural immunological responses (critical for vaccine effects). It has been reported that for every viral infection, the human cell upon acquiring it secretes interferons – a communication message to the neighbouring uninfected cells that I am doomed (by viral infection), please try to save yourself and do something. We learned from the previous coronavirus causing Severe Acute Respiratory Syndrome (SARS) that cells infected with this virus lose the capability to be a good neighbour and cannot share threat to adjacent cells through secreting communication signals, the interferons. Although for SARS-CoV2, this aspect is yet to be deciphered, however, the scientific community believes it might also be the same as its previous cousins SARS and the Middle East Respiratory Syndrome Virus (MERS).
Before, I discuss the ‘game-changing vaccine concept’ endorsed by the World Health Organisation (WHO) on May 6, 2020 entitled, “Key criteria for the ethical acceptability of COVID-19 human challenge studies,” it is pertinent to describe a couple of accomplishments in COVID-19 therapeutics. The Food & Drug Administration in a letter to the Gilead Sciences Inc states, “This letter is in response to your request that the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for emergency use of remdesivir for the treatment of hospitalised 2019 coronavirus disease (COVID-19) patients.”
Remdesivir is just okay, and an excellent remedy is yet to be discovered. Besides its inherent side effects, therapeutic claims are treatment periods of patients suffering from COVID-19 reduced from 15 to 11 days and lowered mortality from 11.6 to 8 percent. Though impressive, the public will hardly accept medicine that only saves four people and let the other eight die with infection. On top of this, pricing by the Gilead Sciences, the manufacturer of this antiviral, is supposed to be very hard to afford by poor nations.
We have been hearing good news about plasma therapy, but the big question is, is this the ultimate cure for masses prone to infection? The simple answer is no, plasma therapy, utilising the passive immunisation concept, is just like borrowing immunity to kill the enemy (the virus). However, it has the potential to save the lives of the critically ill. The ultimate cure still lies in finding a safer and efficacious vaccine.
The game-changing idea of having vaccine quickly for COVID-19 and avoiding potential conflicts among different manufacturers is to implement human challenge studies mainly in Phase III trials, which is considered as the lengthiest phase in the development of novel vaccines. After pre-clinical studies in vaccine development during Phase I, the new vaccine is tested among 20-100 healthy volunteers for its dosage safety. In Phase II, the administration of vaccines among several hundred volunteers assesses its immune responses. Phase III is elaborate, and thousands of volunteers participate. Challenge studies mainly reduce timings during Phase III. This involves the recruitment of volunteers willing to accept intentional infection with the virus instead of letting the people go away and wait for a longer time. The generalised concept of placebo (people having no vaccine) will be existing; however, several vaccines can be evaluated in such studies. The benefit of such trials is that the efficacy of a vaccine can be assessed within the shortest possible time. However, the major drawback is that people receiving a placebo can face severe adverse events, including death. Individuals volunteering for such clinical trials might be in short supply; however, support and volunteerism for such experiments can be ascertained from the fact that more than 15000 have already signed up according to information available Day Sooner, a website dedicated to COVID-19 human challenge trials. These challenge trials will be a game-changer in vaccine development to effectively ward off COVID-19 causing virus. Importantly, challenge trials already brought fruitful results in the finding therapeutics for influenza, malaria, typhoid, dengue fever, and cholera.
The volunteers participating in challenge trials will be putting their lives at risk to save humanity across the world. The World Health Organisation’s backing for such tests comes with precautionary measures falling in eight distinct domains including: SARS-CoV-2 challenge studies must have strong scientific justification; it must be reasonable to expect that the potential benefits of SARS-CoV-2 challenge studies outweigh risks; SARS-CoV-2 challenge research programmes should be informed by consultation and engagement with the public as well as relevant experts and policy-makers; challenge study research programmes should involve close coordination between researchers, funders, policy-makers and regulators; should be situated where the research can be conducted to the highest scientific and ethical standards; researchers should ensure that participant selection criteria limit and minimize risk; the study should be reviewed by a specialised independent committee and it must involve rigorous informed consent.