CureVac has presented more clinical data on its COVID-19 vaccine candidate. The results strengthen the impression that the vaccine triggers potentially protective immune responses while leaving scope to question whether CureVac can clear the bar set by its more advanced rivals.
Based on their early-phase data and the limited look at phase 3 results, Pfizer and BioNTech look set to provide a tough benchmark for other COVID-19 vaccines, both in terms of effectiveness and safety. CureVac, which, like Pfizer and BioNTech, is developing a mRNA vaccine, shared the most detailed look yet at the likelihood of it meeting or exceeding the benchmark in a preprint paper Monday.
The preprint expands on the top-line results CureVac released earlier this month. All participants who took the 12-μg dose selected for further development experienced a fourfold increase in virus-neutralizing antibodies by Day 43. More than 90% had antibodies against both the receptor-binding domain and spike protein. The data come from 11 participants. Lower-dose cohorts, which were part of the original trial design, had data on more subjects by the time the preprint was written.
Antibody titers in subjects who received the 12-μg dose of CVnCoV are in the same ballpark as those seen in people who received the chosen dose of Pfizer and BioNTech’s vaccine, although differences in how different labs perform the assay render the value of such cross-trial comparisons questionable.
Comparisons of safety and tolerability data may be more reliable, although the typical caveats about cross-trial assessments still apply. Based on early-phase data, Pfizer and BioNTech may have an edge over CureVac in terms of safety and tolerability.
In CureVac’s 12-μg cohort, 93% of participants experienced pain after the first injection. Pfizer and BioNTech also reported similar levels of pain. However, the vast majority of cases of pain were mild in the Pfizer and BioNTech study. One-third of the pain cases linked to the first 12-μg dose of CVnCoV were moderate, making it more comparable to the jab Pfizer and BioNTech dropped after phase 1.
Systemic reactions were more common in the CureVac trial, too. Fifty-seven percent of people who received the 12-μg dose of CVnCoV experienced fever after the first injection. Most of the fever cases were moderate or severe. In contrast, around one-fifth of subjects who received BNT162b2 in phase 1/2 had fever after the first dose. None of the cases were severe.
Most of the events resolved within 48 hours and, in the context of the role the vaccine may play in the elimination of COVID-19, are relatively minor. Yet, vaccine tolerability could be a barrier to the widespread uptake of prophylactics needed to bring the coronavirus under control. The influence of tolerability on uptake will only become clear once mass immunization programs begin.
CureVac, which is closing in on the start of phase 3, could contribute to those vaccination programs. While CureVac is behind several COVID-19 vaccine developers, its 2021 target for bringing CVnCoV to market gives it a shot at playing a role in ending the pandemic, given demand for the first products is likely to exceed supply for some time.
Shares in CureVac rose 8% following the publication of the preprint.