In newly released Phase III data, Valneva’s Covid-19 vaccine candidate, VLA2001, showed superior neutralising antibody levels and an equal seroconversion rate compared to AstraZeneca’s Vaxzevria vaccine. A similar number of Covid-19 infections were observed in the VLA2001 and Vaxzevria groups. In addition, Valneva’s vaccine showed a better tolerability profile than Vaxzevria, according to Valneva, potentially making it a strong competitor in the European Covid-19 vaccine market. This study is also one of the first Phase III trials in which a new vaccine candidate was compared to a marketed vaccine, as comparisons with placebo would be unethical.

If Valneva’s safety data holds up, the low risk of thromboses events with AstraZeneca’s and Johnson & Johnson’s (J&J) adenovirus vector-based vaccines may become another important factor in deciding which vaccine to use. It is unlikely, however, that Valneva can match the manufacturing capacity of AstraZeneca and J&J and their partners, as Valneva is a small company that currently has no partnerships or supply contracts for its Covid-19 vaccine. The UK cancelled a supply contract of more than 100 million vaccine doses with Valneva last month. Valneva must also evaluate whether or not it can match Vaxzevria’s low price and still recoup its investment.

Valneva’s new data could also be bad news for adenovirus vector-based vaccine technology in general, given its potentially equal protection, as well as its better tolerability and safety data. Valneva uses an inactivated vaccine technology, which is well-established and can be ramped up quickly. The technology involves the virus being grown in cell culture and then inactivated, also using an adjuvant to enhance the immune response. Another advantage is the fact that the SARS-CoV-2 spike protein is not the only protein included in the inactivated vaccine, as is the case in adenovirus vector-based based and messenger ribonucleic acid (mRNA) vaccines. Instead of this, the whole virus with all its components is included. As a result, the human body can develop antibodies to different parts of the virus, potentially enhancing the immune response.

The mRNA vaccines are still the clear leader in the Covid-19 vaccine market, with their superior effectiveness. Long-term data from Pfizer/BioNTech and Moderna indicates that protection wanes after six months, making booster shots necessary, especially for high-risk groups. If protection from the inactivated vaccine lasts longer, the public health question will be to decide whether better protection, but more frequent boosters are preferable over lower but longer-lasting protection. All vaccines, however, currently show great effectiveness in protection against severe disease and hospitalisation.

This leaves the future competitiveness of adenovirus vector-based Covid-19 vaccines unclear. In addition, Novavax’s recombinant nanoparticle vaccine is close to launching, with Sanofi/GlaxoSmithKline’s recombinant protein vaccine also on track to launch next year. Both of these vaccines use adjuvants. AstraZeneca has, however, a great early-to-market advantage and is planning to supply up to three billion Covid-19 vaccine doses globally this year, together with its manufacturing partner, the Serum Institute of India.