COVID-19 vaccine in the works
With the world literally being put on hold by the SARS-CoV-2 virus, stakeholders around the world are rushing to develop a vaccine that will put back some semblance of normalcy into everyone’s lives.
WHO recently released a list of vaccine candidates being tested around the world, of which some are showing positive early results. There are eight in the clinical trial stage—five in Phase 1/2 stage, two running Phase 1 and Phase 2 separately, and finally one more in Phase 1.
Among the five vaccine candidates in Phase 1/2 stage, three are inactivated virus particles, one utilizes a non-replicating viral vector, and another is based on RNA. The two candidates in Phase 1 and Phase 2 separately are using non-replicating viral vector and mRNA platforms, respectively. Finally, one more candidate still in Phase 1 trials is based on a platform of DNA plasmid with electroporation. Some 110 more vaccine candidates are in preclinical evaluation.
The vaccine candidate receiving some publicity recently is the one by Moderna Inc. in collaboration with the US National Institute of Allergy and Infectious Diseases (NIAID) called mRNA-1273. As the name suggests, it is a lipid nanoparticle (LNP) encapsulated mRNA that codes for a prefusion stabilized form of the spike or S protein of SARS-CoV-2. This vaccine is thought “to direct the body’s cells to express the spike protein in the prefusion [before it fuses with the target receptor] conformation to elicit an immune response.” [Available at www.niaid.nih.gov/news-events/atomic-structure-novel-coronavirus-protein. Accessed on 20 May]
According to NIAID, the SARS-CoV-2 virus spike “undergoes a massive rearrangement as it fuses the virus and cell membranes.” What this means is that the original spike stabilized in its pre-fusion state or conformation is a better target for infection-blocking antibodies induced by a vaccine.
Moderna is ahead of the race due to its previous research into a Middle East Respiratory Syndrome-Coronavirus (MERS-CoV) vaccine, which never took off. However, despite reporting positive results in its initial findings, some experts believe it may be too early to say if the results can be translated into a viable product. [Available at www.statnews.com/2020/05/19/vaccine-experts-say-moderna-didnt-produce-data-critical-to-assessing-covid-19-vaccine/. Accessed on 20 May]
Beyond vaccines, there are some medications being developed that are not vaccine in nature. For instance, Peking University has announced it is working on neutralizing antibodies, which were isolated from the blood of 60 recovered patients. The team at Peking University, led by Professor Xiaoliang Sunney Xie, director of Beijing Advanced Innovation Center for Genomics (ICG) identified multiple highly potent neutralizing antibodies against the novel coronavirus SARS-CoV-2 from convalescent plasma by high-throughput single-cell sequencing. The team expects the therapeutic neutralizing antibodies to be ready by winter in China (traditionally December to February-March). [Available at
https://phys.org/news/2020-05-team-effective-sars-cov-neutralizing-antibodies.html. Accessed on 20 May]
WHO is careful to note that the listing of these vaccine candidates does not translate into approval or endorsement of the products or businesses associated with it.