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Nir Eyal and Marc Lipsitch on methods for further testing of COVID vaccines

March 3 2021

In a paper in Clinical Infectious DiseasesCPLB director Nir Eyal and Harvard epidemiologist Marc Lipsitch demonstrate that it is possible and ethical to use both standard and innovative trial designs to continue testing existing and new COVID vaccines, notwithstanding ethical dilemmas about offering some participants only a placebo, when authorized vaccines are increasingly available in rich countries. They assess the scientific and ethical merits of randomized controlled trials (RCTs) comparing first- and second-generation vaccines, RCTs comparing second-generation vaccines to placebo, challenge trials, and immune bridging studies. 

In Clinical Microbiology and Infection, Eyal and Lipsitch describe an innovative method of challenge designs with deliberate natural viral exposure, instead of exposing participants to a defined viral strain with intranasal inoculation. They compare this new method to a conventional challenge design and to a conventional phase III field trial, and argue that challenge designs with deliberate natural viral exposure have ethical, scientific, and feasibility strengths.