Upsizing and restarts: Covid vaccine trials rumble on

The pause on enrolment into Astrazeneca’s pivotal Covid-19 vaccine study proved short-lived; the trial resumed in the UK six days after a safety concern halted proceedings. However, a substantial expansion of the Pfizer and Biontech trial, also announced over the weekend, shows that other developers are having to proceed carefully. Almost 50% more subjects will be sought as the partners seek to increase population diversity, in terms of age and underlying conditions, as well as adding to safety and efficacy data. Adequately reflecting target populations will be important as developers present findings to regulators and, ultimately, the public – Moderna has also been actively improving the representation of minority groups in its programme. Another potential motivation for the upsizing could be to improve the trial’s chances of showing a benefit, so this might not be an encouraging sign. Leerink analysts suspect the motivation is more likely to be regulatory and commercial – striving for a best-in-class breadth of label – and note that the new patients are unlikely to contribute to an interim read-out anyway, which remains on track for October. With Merck also entering the clinic last week, all of these developers will need to start thinking about differentiation.

Selected Covid-19 vaccines projects 
Project Company Phase III trial ID Notes
BNT162b2 Biontech/Pfizer NCT04368728 30,000 enrolled by mid-September; 44,000 target. 
mRNA-1273 Moderna/NIAID NCT04470427 23,497 of 30,000 target*
AZD1222 Astrazeneca/ Uni of Oxford NCT04516746 (US phIII)                      NCT04400838 (UK phII/III) 17,000 patients enrolled so far in UK, Brazil, South Africa
Ad26.COV2-S Johnson & Johnson NCT04505722 Starting in Sept, 60,000 target
Ad5-nCoV Cansino Biologics NCT04526990 (Pakistan) Not yet recruiting, 40,000 target
CoronaVac Sinovac NCT04456595 (Brazil) & NCT04508075 (Indonesia) Unknown, 8,800 & 1,600 target
NCT04533399 Ph2 started Aug 2020; Ph3 to start Oct 2020, target 30,000
CVnCoV Curevac NCT04515147 Ph2 started Aug 2020
SARS-CoV-2 vaccine GSK/Sanofi NCT04537208 Ph1/2 started Sep 2020, ph3 to start by YE'20
V591 Merck (Themis) NCT04498247 Ph2 started Sept
*As of Sept 11, 2020. Source: EvaluatePharma,, company statements.

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