The CanSino vaccine, which is being developed with the Beijing Institute of Biotechnology, also uses an adenovirus as a viral vector to deliver the coronavirus spike protein, but in this case it is a common cold virus that infects humans. One potential downside to this, Kampmann says, is that, as the virus circulates in human populations, some people may already have antibodies to it, which could affect the immune response. “It could be that people with preexisting antibodies against that adenovirus won’t make as much of an immune response to the adenovirus Covid vaccine,” she says.
The vaccine has been approved for use by the Chinese military.
The US company Moderna is one of several groups working on an RNA vaccine, a new type of vaccine that involves making a synthetic version of the coronavirus spike protein’s RNA—the genetic instructions that tell cells how to make the protein. This tricks the body into making the spike protein itself, which induces an immune response.
On July 14, preliminary results from a Phase II trial of the Moderna vaccine were published in The New England Journal of Medicine and stated that the vaccine had induced an immune response and raised no major safety concerns. Moderna began Phase III trials on Monday.
The advantage to the RNA approach is that you don’t have to make lots of material, as the body essentially creates the vaccine itself. This could make it easier to scale and cheaper to produce. “You can get away with very, very small quantities,” Kampmann says. However, it is relatively new in the world of vaccine technology; no RNA vaccine has previously been licensed.
Other groups working on RNA vaccines include Imperial College London and the German company BioNTech; the latter is working with pharma giant Pfizer and has an agreement with the UK government to supply 30 million doses.
Beijing-based Sinovac Biotech’s vaccine candidate, called CoronaVac, is an inactivated vaccine—a comparatively old-fashioned type of vaccine that consists of virus particles that have been killed or inactivated and so no longer cause infection. The immune system still recognizes the virus, provoking an immune response that it can call upon if the recipient later comes into contact with the real thing.
In June, the company said in a press release that preliminary results from its Phase I and II studies in humans showed that the vaccine induced neutralizing antibodies and had no severe side effects. It is now moving on to Phase III studies in Brazil.
One advantage of the inactivated virus approach, says Altmann, is that it is tried and tested; the same technique has been used for decades to make vaccines to protect against diseases such as polio. “I like that logic,” Altmann says. This also means we already have the infrastructure to make this kind of vaccine.
A disadvantage, however, is that making the vaccine requires growing the material in vast quantities, which may make it harder to scale than other vaccine types—an important consideration given the scope and urgency of demand for a Covid-19 vaccine.
China’s SinoPharm is also developing an inactivated vaccine and is conducting a Phase III trial in Abu Dhabi.
A Long Way to Go
There are of course many other vaccines being worked on, and picturing the quest for a Covid vaccine as a “race” may be misleading. “This isn’t actually a quick sprint, this is a marathon,” Kampmann says.
Being first doesn’t necessarily mean being best, and there are other issues beyond just making a vaccine that works. We will need to manufacture and distribute the vaccine at great scale, and we won’t know how long a vaccine protects a person from Covid-19 until later down the line. A vaccine that takes longer to develop may prove more effective, longer-lasting, cheaper, or easier to scale. Or different vaccines may prove more effective in different geographies or age groups. “It might well be there’s going to be more than one vaccine,” Kampmann says. “I would be very surprised if there was only one vaccine that came through.”
For now, Altmann says, it’s important to invest in lots of different platforms and candidates rather than put all our eggs in one basket in a rush to back a single “winner.” “It’s an argument for trying to be slow and wise and careful, and not jumping at it as if it was the Eurovision Song Contest of vaccines,” he says.
This story originally appeared on WIRED UK.
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