The ChAdOx1 nCoV-19 vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), described by Pedro Folegatti and colleagues,1 was an important milestone in vaccine development to contain the ongoing pandemic. The vaccine is one of several SARS-CoV-2 vaccines that have entered the human trial phase, and the phase 1/2 trial showed encouraging results. This trial has focused on the most relevant clinical outcomes of safety, reactogenicity, and immunogenicity of the vaccine. The recruited participants (ie, healthy adults aged 18–55 years who were negative for SARS-CoV-2) were randomly assigned to receive either the vaccine (ie, ChAdOx1 nCoV-19 at a dose of 5 × 104 viral particles) or an active control (ie, a meningococcal conjugate vaccine; MenACWY) as a single intramuscular injection. The study showed the safety, reactogenicity, and immunogenicity of the ChAdOx1 nCoV-19 vaccine.
Although the outcomes were meticulously planned, an important outcome, anaphylactic reaction, was not mentioned. Anaphylaxis is important to consider while a new vaccine is being tested.2 Additionally, the selection criteria for ten participants in group 3, who were recruited in a non-randomised way, needs to be described. The trial is labelled as a randomised controlled trial and the criteria for recruiting participants in a non-randomised method should be made available. While we looked at the immunogenicity outcomes in figure 3,1 we noted that the number of participants who were analysed was different at each follow-up stage. Some explanation for this difference needs to be given to make the findings more applicable. In the trial, participants with high titres of neutralising antibodies at baseline were also included in the same analysis, but whether the rise in their antibody titres affected the overall results and whether the non-randomised recruitment of the participants influenced the comparison is unclear. In the group of participants receiving ChAdOx1 nCoV-19 and paracetamol, the adverse event of itching was higher than in participants receiving ChAdOx1 nCoV-19 without paracetamol, which needs to be investigated.
Although phase 2 trials are usually underpowered for reporting of efficacy outcomes,3 Folegatti and colleagues have planned to assess them. We hope to read about the results of the vaccine trial soon.
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Acknowledgments
We declare no competing interests.
References
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