A coronavirus jab based on traditional vaccine technology might be as effective as the Oxford/AstraZeneca vaccine, data suggests, offering new hope for global vaccination efforts.
Vaccines currently approved for use in the UK deliver instructions for producing the coronavirus “spike” protein to cells in order, which triggers an immune response. However, the jab produced by the French pharmaceutical company Valneva involves delivering the whole – but inactivated – Sars-CoV-2 virus.
Last month the government cancelled its contract with Valneva, which included an order for about 100m doses of the vaccine, over an alleged breach of the agreement.
Not only has it been suggested that inactivated whole-virus vaccines may result in a broader immune response, but the approach could also help to maintain protection in the face of new variants. This is because it is unlikely that mutations will crop up at the same time in multiple proteins of the virus.
The Valneva jab is also stable when stored in a standard refrigerator, making it easier to distribute than the Covid vaccines, which require shipping and storage at ultra-low temperatures.
Results released by Valneva on Monday suggest that the Covid vaccine may trigger a stronger immune response than the Oxford/AstraZeneca jab.
Prof Adam Finn of the University of Bristol, the trial’s chief investigator, said that it was not ethically possible to compare the Valneva jab against a placebo, meaning efficacy could not be measured. Instead the vaccine was compared in a head-to-head trial against the Oxford/AstraZeneca jab.
The phase 3 study, dubbed “Cov-Compare”, involved 4,012 participants aged 18 years and older across 26 trial sites in the UK.
The 1,040 participants under 30 were given two doses of the Valneva jab 28 days apart, while the remaining participants, aged 30 and over, were randomised in a 2:1 ratio to receive two doses of either the Valneva jab or the Oxford/AstraZeneca vaccine.
The results from 990 participants aged 30 or over – about half of whom were given each jab – suggest the Valneva Covid vaccine, VLA2001, triggered about 40% higher levels of neutralising antibodies on average than the Oxford/AstraZeneca vaccine.
Like the Oxford/AstraZeneca vaccine, the Valneva jab was found to stimulate responses from other components of the immune system, including T-cells. However, the Valneva jab gave rise to T-cells able to respond not only to the coronavirus spike protein, but to two other key proteins.
The team found fewer side-effects were reported in those given the Valneva jab. However, fewer than 1% of participants given either jab reported an “adverse event of special interest”, while no participants developed a severe Covid infection.
“Participants in the younger age group vaccinated with VLA2001 showed an overall safety profile comparable to the older age group,” the team add.
Finn said it would take observational studies to confirm just how effective the Valneva jab was against Covid, an approach that has previously been used to evaluate meningitis B jabs.
“The efficacy of a vaccine is not proportional to the antibody titres that it generates,” he said, noting that it was thought there was a threshold above which one was protected. “It’s about having enough antibody, rather than just looking at how much antibody there is, and imagining that tells you how well [the jab will] work,” he said.
Nonetheless, Finn said, the results were “very encouraging”.
“The immunogenicity [data] would suggest that it will be at least as effective and potentially more effective than the Oxford vaccine, which sets a really good precedent, because that vaccine is highly effective against severe disease, as is the Pfizer vaccine.”
While the integrity of the Valneva study data is now undergoing validation, the team hope the jab will be approved by the UK’s Medicines and Healthcare products Regulatory Agency by the end of the year.
Dr Juan Carlos Jaramillo, the chief medical officer for Valneva, said the company was initially seeking approval for its Covid jab for people aged 18-55, adding that trials were ongoing among older adults. Recruitment has begun for trials involving older children, while the team is also exploring use of the jab as boosters.
Once approved, the jab could be considered by the World Health Organization. Jaramillo said the company was in discussions with Covax, the global vaccine-sharing initiative.
The jab could prove particularly useful in countries where ultra-low-temperature storage is hard to come by, but Finn suggested it may also bring benefits elsewhere, noting that the traditional technology might be more acceptable to those who have been reluctant to receive a Covid jab because of concerns over newer vaccine platforms.
