Researchers from China have published results about the safety and efficacy of a whole-virus vaccine. The vaccine triggers an immune response, and side effects were rare and mild.
So far, so good
It’s been about four months since vaccine research kicked off in force. At the start of the vaccine race, most researchers considered a one-year timeline to be the most optimistic, best-case scenario we can expect. Remarkably, we’re making good progress to that goal.
Already, several vaccines are entering Phase 3 trials, where their efficacy and side effects will be assessed on a large sample size of thousands of patients. What’s even more encouraging is that there are several different avenues being pursued by the different candidates.
The new vaccine, developed by researchers at Sinopharm, a unit of China National Pharmaceutical Group, is the first to use a protein immunogen. Essentially, it’s a whole-virus inactivated COVID-19 vaccine, a different approach from what other advanced candidates are doing.
“The so-called genetic immunization candidate vaccines, including messenger RNA, DNA, and nonreplicating viral vectors such as recombinant adenovirus, were the first vaccine candidates to report interim results of early-phase clinical trials because these platforms are preexisting, flexible, rapid, and scalable. Therefore, genetic immunization approaches are particularly suited to a rapid pandemic response,” writes Mark J. Mulligan, professor at the NYU Grossman School of Medicine, in a commentary article on the new vaccine.
Protein immunogens are a different, more traditional category of vaccines, Mulligan explains. The polio vaccine is the classic example of this type of approach, and it’s a well-trodden path in regards to vaccine development.
The Sinopharm trials consisted of 2 randomized placebo-controlled trials. In the phase 1 trial, 96 healthy adults were administered low, medium, and high vaccine doses, three times: on day 0, day 28, and day 56. Side effects were reported in 20.8%, 16.7%, and 25.0% of cases respectively, but the main side effects were mild: injection site pain and fever. The placebo group (which received a non-vaccine injection) also reported side effects in 12.5% of cases overall, indicating that the vaccine itself only causes mild side effects in a minority of cases. The good health of participants was assessed through self-reports as well as blood tests.
In phase two, 224 healthy adults tested the vaccine, and confirmed the phase 1 results: the whole-virus vaccine candidate was tolerated, safe, and produced antibodies at 14 days after the booster vaccine (the second dose).
“This inactivated COVID-19 vaccine had a low rate of adverse reactions and demonstrated immunogenicity, but longer-term assessment of safety and efficacy will require phase 3 trials,” the researchers conclude.
The more the merrier
The results are encouraging, though limited, as the team led by Shengli Xia acknowledges. The trials are still ongoing, however, and phase 3 trials have just started. Ironically, the phase 3 trial (which aims to recruit 15,000 people) has been moved to the United Arab Emirates, as China has too few new cases to be a useful trial site — that’s one problem that’s not too bad to have.
Just because the Sinopharm vaccine was successful in phase 1 and 2 trials doesn’t necessarily mean it will work in a larger sample size. But, at least so far, the results are indeed promising.
There are few guarantees when attempting to develop a vaccine. Multiple approaches can be successful, or it could be that none of them works. The more teams working on the case, and the more vaccine types, the more the likelihood that one (or several) vaccines succeed. Furthermore, even if one or more vaccine candidates are successful, producing and distributing billions of doses is a mammoth challenge in itself. If more companies develop a working vaccine, that’s good news for everybody, because the load of production distribution will be shared.
“With 7.8 billion individuals worldwide at risk for SARS-CoV-2 infection and COVID-19 morbidity and mortality, humanity needs as many safe and protective COVID-19 vaccines as possible,” Mulligan concludes.
The study has been published in JAMA.