A comparison of vaccinations has demonstrated that mRNA vaccines perform better against variants of concern (VOCs) than viral vector vaccines. Although they all effectively prevent severe disease by VOCs, the research published in PLOS Medicine suggests that people receiving a viral vector vaccine are more vulnerable to infection by new variants.
The Pfizer-BioNTech and Moderna are mRNA vaccines, which deliver genetic code to the bodies’ cells, whereas Oxford/AstraZeneca and J&J are viral vector vaccines which uses a modified virus to deliver instructions. J&J is delivered as a single dose while the rest are administered two weeks apart.
Marit J. van Gils at the University of Amsterdam, Netherlands, and colleagues, took blood samples from 165 healthcare workers, three and four weeks after first and second vaccination respectively, and for J&J at four to five and eight weeks after vaccination. Samples were collected before, and four weeks after a Pfizer-BioNTech booster.
Four weeks after the initial two doses, antibody responses to the original SARS-CoV-2 viral strain were highest in recipients of Moderna, followed closely by Pfizer-BioNTech, and were substantially lower in those who received viral vector vaccines. Tested against the VOCs Alpha, Beta, Gamma, Delta and Omicron, neutralising antibodies were higher in the mRNA recipients than the viral vector recipients. Neutralisation ability against VOCs was reduced in all vaccine groups, with the greatest reduction against Omicron. The Pfizer-BioNTech booster increased antibody responses in all groups with substantial improvement against VOCs, including Omicron.
The researchers caution that their AstraZeneca group was significantly older, because of safety concerns for the vaccine in younger age groups. As immune responses tend to weaken with age, this could affect the results. This group was also smaller because the Dutch government halted use for a period.
Afrigen Biologics and Vaccines, a South African biotechnology company, has nearly created a copy of Moderna’s COVID mRNA vaccine, without Moderna’s involvement, Nature reports.
The Cape Town-based company has so far made only microlitres of the vaccine, based on Moderna’s publicly available development data. This nevertheless is a success for a major initiative launched by the World Health Organization (WHO): a technology transfer hub meant to build vaccine manufacturing capacity in low- and middle-income countries.
During the COVID pandemic, the developers of mRNA vaccines, Moderna and Pfizer/BioNTech have sent more than 70% of their doses to wealthy nations. Meanwhile, millions of vaccine orders for southern hemisphere countries have been delayed. “Moderna and Pfizer-BioNTech’s vaccines are mainly still going to just the richest countries,” says Martin Friede, the WHO official coordinating the hub. “Our objective is to empower other countries to make their own.”
Much work needs to be done before Afrigen’s mRNA vaccine mimic can be distributed. But the WHO hopes that the process of creating it will lay the foundation for a more globally distributed mRNA vaccine industry in the future.
Gerhardt Boukes, chief scientist at Afrigen is proud to have helped complete this first step of the plan. Afrigen and its collaborators completed the process, beginning with mRNA encoding a modified portion of the SARS-CoV-2 coronavirus, and finishing by encapsulating it in a lipid nanoparticle that delivers the vaccine to cells. “We didn’t have help from the major COVID vaccine producers,” he says, “so we did it ourselves to show the world that it can be done, and be done here, on the African continent.”
When the mRNA hub was launched by the WHO in June 2021, Moderna, Pfizer and BioNTech did not respond to requests to help make their vaccines, so the WHO proceeded without their help. The Moderna vaccine was chosen to copy because there is more freely available data on it, and it has not vowed to enforce its patents.
The project started in late September, with a Wits University team spearheading the first step: making a DNA molecule that would serve as a template to synthesise the mRNA needed in the vaccine. While Moderna controversially patented this sequence, Stanford University researchers had deposited it into the online database Virological.org in March last year.
Patrick Arbuthnot, director of gene therapy research at Wits says, “We were not intimidated, because mRNA synthesis is a fairly generic procedure.” Despite delays in the shipment of raw materials, the team completed this process in ten weeks and sent vials of mRNA to Afrigen in early December.
Around this time, scientists worldwide emailed offers of assistance. Some were researchers at the US National Institutes of Health who had conducted foundational work on mRNA vaccines. Petro Terblanche, Afrigen’s managing director, said that it was “extraordinary”. “I think a lot of scientists were disillusioned with what had happened with vaccine distribution, and they wanted to help get the world out of this dilemma.”
On 5 January, Afrigen’s researchers accomplished another tricky part of the process: They encapsulated the mRNA in a fatty nanoparticle made of a mixture of lipids. Boukes says they haven’t yet used Moderna’s specific lipid mixture, but rather another one that was immediately available from the manufacturer of the machine that the laboratory uses to create lipid nanoparticles. They plan to use Moderna’s lipid mixture in the coming days, as soon as one last analytical instrument arrives. After that, the team will analyse the formulation to ensure that it is truly a near copy of Moderna’s vaccine.
Once a reliable copy is made, the next step is increasing production. Jason McLellan, a structural biologist at the University of Texas at Austin whose work was foundational to the development of several COVID vaccines, says he is not surprised that SA scientists seem to have copied Moderna’s vaccine, but he adds that scaling up production of that original shot required a lot of additional innovation by manufacturers.
For the next phase of the project, several southern hemisphere companies will learn from Afrigen and attempt to create batches of vaccines themselves, in preparation for animal testing. By end November, the WHO expects a Moderna clone to be ready for phase I trials in humans.
What happens beyond that is unclear. Moderna might choose to license its patent (lab research is usually not subject to patent rules), or alternatives may become available, such as next-generation mRNA vaccines that do not require ultracold storage.
A series of studies in recent months has found that, thanks to the mRNA vaccine and previous infection, some people mount an extraordinarily powerful immune response against SARS-CoV-2 which some scientists have referred to as ‘superhuman’.
Called ‘hybrid immunity’, their bodies produce very high levels of antibodies, with great flexibility: likely capable of fighting off the SARS-CoV-2 variants currently circulating but also likely effective against future variants.
“Overall, hybrid immunity to SARS-CoV-2 appears to be impressively potent,” Crotty wrote in commentary in Science published in June.
“One could reasonably predict that these people will be quite well protected against most and perhaps all of — the SARS-CoV-2 variants that we are likely to see in the foreseeable future,” says Paul Bieniasz, a virologist at Rockefeller University who helped lead several of the studies.
Bieniasz and his colleagues found antibodies in these individuals capable of strongly neutralising the six variants of concern tested, including Delta and Beta, as well as several other viruses related to SARS-CoV-2, including SARS-CoV-1.
“This is being a bit more speculative, but I would also suspect that they would have some degree of protection against the SARS-like viruses that have yet to infect humans,” Bieniasz said.
People who have had a ‘hybrid’ exposure to the virus, were infected with it in 2020 and then immunised with mRNA vaccines this year. “Those people have amazing responses to the vaccine,” said virologist Theodora Hatziioannou at Rockefeller University, who also helped lead several of the studies. “I think they are in the best position to fight the virus. The antibodies in these people’s blood can even neutralize SARS-CoV-1, the first coronavirus, which emerged 20 years ago. That virus is very, very different from SARS-CoV-2.”
These antibodies were so effective they were even able to deactivate a virus purposefully engineered to be highly resistant to neutralisation, containing 20 mutations that are known to prevent SARS-CoV-2 antibodies from binding to it. Antibodies from those who were only vaccinated or who only had prior coronavirus infections were ineffecgtive against this engineered virus..
This shows how powerful the mRNA vaccine can be in those infected with SARS-CoV-2, she said. “There’s a lot of research now focused on finding a pan-coronavirus vaccine that would protect against all future variants. Our findings tell you that we already have it.
The catch is getting COVID. “After natural infections, the antibodies seem to evolve and become not only more potent but also broader. They become more resistant to mutations within the [virus].”
Hatziioannou and colleagues don’t know if this applies to all those mRNA-vaccinated and previously COVID-infected. “We’ve only studied the phenomena with a few patients because it’s extremely laborious and difficult research to do,” she said. “With every single one of the patients we studied, we saw the same thing.” The study reports data on 14 patients.
Several other studies lend credence to her hypothesis and reinforce the idea that exposure to both a coronavirus and an mRNA vaccine triggers an exceptionally powerful immune response. In one study in NEJM, scientists analysed antibodies generated by people who had been infected with SARS-CoV-1 back in 2002 or 2003 and who then received an mRNA vaccine this year.
Remarkably, these people also produced high levels of antibodies that could neutralise a whole range of variants and SARS-like viruses. Many questions remain, such as the effect of a third booster shot, or being infected again.
“I’m pretty certain that a third shot will help a person’s antibodies evolve even further, and perhaps they will acquire some breadth [or flexibility], but whether they will ever manage to get the breadth that you see following natural infection, that’s unclear.”
Immunologist John Wherry, at the University of Pennsylvania, is a bit more hopeful. “In our research, we already see some of this antibody evolution happening in people who are just vaccinated,” he said, “although it probably happens faster in people who have been infected.”
In a recent study, Wherry and colleagues showed that, over time, uninfected people with only two doses of the vaccine begin to produce more flexible antibodies, so a third dose would give even more of an evolutionary boost to the antibodies, Wherry said. So a person will be better equipped to fight off whatever variant the virus puts out there next.
“Based on all these findings, it looks like the immune system is eventually going to have the edge over this virus,” said Bieniasz, of Rockefeller University. “And if we’re lucky, SARS-CoV-2 will eventually fall into that category of viruses that gives us only a mild cold.”
