It won’t be before mid-2021 that a limited dose of Covid vaccine reaches various countries. Here are the top contenders among 36 vaccines in clinical trials.
The global race for a COVID-19 vaccine is heating up—and there’s keen discussion on claims and disclosures. Even as clinical trials are on, there’s a hectic parallel effort on the manufacturing and access front. After all, as the World Health Organization’s chief scientist Soumya Swaminathan put it recently, this is the first time that the world will need vaccines in billions of doses.
An actual licensed vaccine is still far off—at least mid-2021 for a limited dose to arrive in countries, according to WHO. So what does the current scenario look like? As of mid-September, there were 36 vaccine candidates in various stages of clinical trials (this includes Bharat Biotech’s indigenous vaccine called Covaxin) and 146 others in pre-clinical evaluation. Here’s a look at the candidates currently in Phase III trials.
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AstraZeneca/University of Oxford
This candidate named AZD1222 is based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. Results of the Phase I/II trial published in July showed that participants who received the vaccine had detectable neutralising antibodies—the ongoing large-scale trials will assess whether it can effectively protect against SARS-CoV-2 infection. But clinical trials were paused briefly in early September after a UK participant developed ‘an unexplained illness’. The UK trials resumed a week later after the go-ahead from the regulator, but the US trials are yet to. Ongoing trials in India by vaccine manufacturer Serum Institute of India—in partnership with AstraZeneca—have since also been allowed to resume.
CanSino Biological Inc
Jointly developed by Chinese firm CanSino, Beijing Institute of Biotechnology and Academy of Military Medical Sciences, international Phase-III trials of this Adenovirus Type 5 Vector vaccine (Ad5) began in September. This week, its Russian partner Petrovax said that the first group of volunteers were vaccinated in medical centres in Moscow. CanSino had previously worked on the common cold-based Ad5 vaccine for Ebola, which was approved in China for emergency use. (Human adenoviral vectors have been experimented upon for various diseases such as AIDS. But so far there has not been a commercially approved adenovirus vector vaccine for use in humans)
Gamaleya Research Institute
Sputnik V, named after the Russian satellite that launched the space race in the late 1950s, made a splash last month as the first Covid vaccine to be registered—by the Russian Ministry of Health—on the market. Sputnik V is a two-dose vaccine using the human recombinant adenovirus vectors Ad5 and Ad26. Does it work? That’s the million-dollar question. Early September, the Gamaleya National Research Centre of Epidemiology and Microbiology published the results of Phase I-II clinical trials in The Lancet. First results of the ongoing post-registration clinical trials involving 40,000 volunteers are expected to be published in October-November, says the Russian Direct Investment Fund (RDIF). Last week, Russia’s sovereign wealth fund signed on Indian pharma company Dr. Reddy’s Laboratories for clinical trials and distribution of Sputnik V vaccine in India. The RDIF says it shall supply 100 million doses of the vaccine upon regulatory approval.
Janssen Pharmaceutical Companies
A Johnson & Johnson company, Janssen’s vaccine candidate is based on the adenovirus serotype Ad26—the company says pre-clinical studies in non-human primates and the Syrian golden hamster rodent elicited an immune response. Phase III trials started this month.
Sinovac
Named Coronavac, this vaccine candidate being developed by Chinese pharma company Sinovac is an inactivated vaccine—meaning it uses the killed germ to elicit an immune response. (Viral vaccines have traditionally been based on inactivated and attenuated, or weakened, pathogens.) Sinovac this month said that a phase I/II clinical trial conducted in China showed safety and immunogenicity on healthy adults aged 60 and above, comparable to its earlier studies on adults aged 18-59. In July, Sinovac announced its Phase III clinical trials in Brazil.
Sinopharm
The China National Biotec Group, a unit of the state-run pharmaceutical company Sinopharm, is developing two vaccine candidates—therefore, there are a total of four Chinese vaccines in late state trials, including CanSino and Sinovac. Recently, Sinopharm began large-scale trials in the UAE.
Moderna
American biotech firm Moderna began Phase III clinical trials in late July. Its CEO recently said it should know by November whether the vaccine works. The firm, an early entrant in the race, is working on messenger RNA technology. It’s an emerging platform where genetic information is used to instruct human cells to create a protein specific to Sars-CoV-2 in order to trigger a defensive immune response.
Pfizer
Another mRNA vaccine, Pfizer is hoping to get a fix on its efficacy by the end of October. Earlier this month, Pfizer and its partner, German firm BioNTech SE, announced that they were expanding enrolment of the Phase III vaccine trial to about 44,000 participants, up from 30,000 currently, which would help increase the trial population diversity.
(Compiled from company press releases, news reports and WHO’s DRAFT landscape of COVID-19 candidate vaccines)
By Ajay Sukumaran in Bangalore