With global vaccine rollout progressing and the number of viable interventions increasing, candidates that are yet to receive regulatory approval risk losing ground. In the US alone there are sufficient doses of Pfizer’s and Moderna’s vaccines to fully vaccinate the entire population, and therefore entry into such an established market may prove difficult for new contenders. This analysis explores the landscape of pivotal COVID-19 studies and assesses the progress of key vaccines awaiting approval.
The greatest proportion of ongoing and planned pivotal COVID-19 clinical trials are in Phase III status (49.3%), outnumbering second-place Phase II/III trials (32.8%). The relatively high proportion of combined Phase II/III studies may allow for an accelerated drug approval as necessitated by the pandemic. As displayed in Figure 1, the US leads as the location with the highest number of pivotal trials in ongoing and planned status, with Brazil in second place (32.8%). The UK and Spain hold third and fourth place respectively, with 23.9% and 20.9% of trials, while South Africa and Mexico follow in joint fifth place with 19.4%. Based on the top trial locations, it appears sponsors take a targeted approach in selecting regions for conducting pivotal studies, with preference for countries where COVID-19 variants have emerged. This may therefore allow for determination of vaccine efficacy against variants, particularly in locations where variants prove to be the dominant strain. However, only 10% of pivotal studies are being conducted in India. With the Indian variant currently responsible for the highest number of COVID-19 cases worldwide, greater representation in pivotal trials is required for emerging vaccines and therapies.
AstraZeneca has the highest number of pivotal studies in planned and ongoing stages of development (4). The company’s vaccine AZD1222 is yet to be granted emergency use authorisation by the FDA, with the regulators requesting further international data due to safety concerns, as blood clots have been linked to vaccine use in Europe and South Africa. Similarly, Novavax’s vaccine candidate is yet to attain FDA approval, with a pivotal Phase III trial currently ongoing in the US and Mexico. Novavax has initiated the process for a rolling review with a number of regulatory agencies including the FDA, European Medicines Agency (EMA), and the Medicines and Healthcare products Agency (MHRA). The company expects approval in the second quarter of 2021 in Europe and the US, especially if the data mirror the positive results disclosed from the Phase III study conducted in the UK. Nonetheless, manufacturing issues continue to prove disruptive; Novavax struggled to procure the required raw materials, resulting in a contract signing delay to deliver vaccines to the European Union. Novavax pushed back its production target of producing 150 million COVID-19 vaccine doses per month from Q2 to Q3 owing to supply shortages. CureVac’s vaccine candidate mRNA CVnCoV is currently undergoing pivotal Phase II/III studies with aims to publish data from the study in the coming weeks alongside a rolling review with the EMA. CureVac may stand to gain from Novavax’s manufacturing issues, with production deals already in place with key players such as GlaxoSmithKline and Bayer. Notably, CureVac’s pivotal Phase II/III studies assess two doses of 12µg of CVnCoV, lower than Pfizer’s 30µg dose and Moderna’s 100µg dose, possibly allowing for a faster speed of manufacture. Valneva has recently initiated a UK-based pivotal Phase III study with VLA2001, proving to be the only inactivated vaccine candidate entering clinical trials in Europe. The study is a comparative immunogenicity trial against AstraZeneca’s AZD1222, with the company seeking to display superior immunogenicity. This marks an evolution in COVID-19 vaccine trial design; as the number of vaccines increase, approval may increasingly be decided on superiority relative to available alternatives as opposed to only demonstrating an adequate efficacy and safety profile.