Parnali Dhar Chowdhury, Ph.D. Research Scientist in the Department of Epidemiology, Johns Hopkins University, USA
If we look back to our history, we will see that Buddhist monks used to drink snake venom to develop strongest immunity against the deadly poisonous substances. Although, modern medical science considers Edward Jenner is the founder of vaccinology in 1796, after he inoculated a 13 year-old-boy with vaccinia virus (cowpox) and demonstrated immunity to smallpox. After that, Louis Pasteur’s experiments lead the development of live attenuated cholera vaccine and inactivated anthrax vaccine in humans (1897 and 1904, respectively). Later, Plague vaccine was also invented. It was last 70 to 120 years only when bacterial vaccine development proliferated, including the BCG (Bacillis-Calmette-Guerin) vaccination, which is still in use today.
The question automatically comes in our mind that how far is COVID-19 vaccine or how difficult it is to make that after almost six months of the SARS-CoV-2 virus attacked, why we don’t have vaccine? What challenges are the front-line scientists facing in top class laboratory all over the world? Finally, if there is no coronavirus vaccine immediately available, what’s next? How do we overcome the COVID-19 challenges if and when there would be second wave of coronavirus peak?
Well, the answers are not easy to give in this context. Coronavirus is a simple RNA enveloped virus (genetic structures are covered with surface glycoproteins). Enveloped viruses have proteins on their surface that drive fusion of the virus and host cell membranes, a key process in infection. Apparently, it seems very easy to think that the immunopathogenesis of coronavirus is easy to study as specially when the scientists have already analyzed the S-glycoprotein structures. To be more specific and simplistic, let me explain here that this S-glycoprotein is in fact the culprit in terms of binding with the receptor binding sites of human cells. Consequently, one can ask the next question as isn’t it obvious that if scientist can somehow know how to block this S-protein to stop binding with the receptor sites of human cells, then the correct vaccine is on its way? So, then why so much delay and nothing is so far on our way? Why not a single vaccine got yet license when the whole genome structure has been revealed on January 11th? Almost five and half months gone after that.
The answer is definitely yes but little complicated. These proteins are also the major target of a protective immune response. Although they are able to induce an immune response, they are inherently unstable and can change shape when expressed on their own. This means that the immune response induced does not efficiently recognize the protein on the virus surface and so does not provide protection from subsequent infection.
Now, it would be worthy to mention few names of global vaccine candidates here to shed some lights on vaccine development. According to WHO list, there are now 115 vaccine candidates who are developing COVID-19 vaccines. The Coalition for Epidemic Preparedness Innovations (CEPI) in partnership with UN foundation and coalition with Welcome trust, Bill and Melinda Gates Foundation, and eight European Countries are one of the largest vaccine funding foundation that have funded some candidates to develop covid-19 vaccines, among which few are leading in the world now. However, it is important to mention here that all vaccines developed now are in clinical trials or pre-clinical phase. CEPI’s COVID-19 vaccine program with Clover Biopharmaceuticals began phase 1 clinical trials on 19 June in Australia. Last week, CureVac which is another vaccine candidate receive regulatory approval and the University of Queensland in Australis started recruiting volunteers for its upcoming Phase 1 trial. Novavax’ NVX CoV2373 vaccine candidate against COVID-19, rapidly advancing the vaccine candidate through clinical trials, while scaling up manufacturing capacity in parallel. Moderna in USA and China’s CanSino Biologics are the first to launch small clinical trials of vaccines on March 16th. As nobody knows which vaccines are going to work, it is important to run multiple vaccine development efforts in parallel to ensure that a vaccine will be available in 18-24 months. All these show a wonderful response from global biomedical community to a pandemic.
Finally, making COVID-19 vaccines available is not only a scientific challenge. Previous health emergencies, such as the 2009 swine flu pandemic and the 2014 Ebola outbreak in West Africa, have shown that it can sometimes be difficult to organize global collective action. While there have been many remarkable examples of countries coming together to help tackle COVID-19 situation, the global COVID-19 response has also been hindered by a lack of international collaboration. Rich countries are already trying to put in place monopoly agreements with potential manufacturers of COVID-19 vaccines.