Coronavirus USA: how many vaccines could fail according to federal advisers?

As of the end of August, there were 33 candidate Covid-19 vaccines in clinical evaluation and another 143 candidate vaccines being developed in pre-clinical evaluation in various different parts of the world. Of the 33 candidate vaccines which have entered Clinical Stage trials, eight are currently in Phase III human testing stage. Phase III trials are large-scale trials involving thousands of participants from different age groups and ethnicity. This stage of testing is used to test the safety and effectiveness of the new vaccine in the kind of patient who is most likely to be administered it, to affirm safe and effective dosage levels, identify any hitherto unknown side effects in individuals with underlying conditions, to gain a clearer indication of the benefits of taking the medicine compared to any risks that might be involved and to compare the results with other existing treatments.

Phase III large-scale testing

Once a candidate vaccine passes the Phase III trial stage and developers are satisfied that the drug is safe and effective, and the benefits of using it far outweigh the negative aspects, only then can it be licensed by the U.S. Food and Drug Administration (FDA). A recent, 15-year study into clinical trial success rates published in Oxford Academic’s Biostatistics journal, compiled data from hundreds of thousands of sponsored industry and non-industry trials and found that candidate vaccines have a 33.4% chance of making it through phase-by-phase clinical trials and to regulatory approval.

Operation Warp Speed - six candidate vaccines

In the United States, the Trump administration’s Operation Warp Speed (OWS) aims to deliver 300 million doses of a safe, effective vaccine for Covid-19 by January 2021. The OWS had 14 candidates when the development plan program was launched in May, since then, almost half of them have been discarded.

Out of the eight vaccines currently in the OWS’ portfolio, six late-stage candidate vaccines have been announced and partnerships established with the respective companies. Out of those six, 30,000-person phase III trials, to be conducted between now and November, the OWS expects only two to be successful - the other four will fail.

The six candidate vaccines being supported by the OWS include: ChAdOx1-S (University of Oxford / AstraZeneca), LNP-encapsulated mRNA (Moderna/NIAID), 3 LNP-mRNAs (BioNTech/Fosun Pharma/Pfizer), the Janssen Ad26 Covid-19 replication-defective live-vector vaccine and Full length recombinant SARS CoV-2 glycoprotein nanoparticle vaccine adjuvanted with Matrix M (Novavax) and Sanofi / GSK’s COVID-19 recombinant protein-based vaccine.

“Four of the trials will fail, and all subjects in those trials are offered access to an approved vaccine,” the National Academies of Sciences, Engineering, and Medicine wrote in their draft report: A Framework for Equitable Allocation of COVID-19 Vaccine. “Three of the trials will succeed, and, under a 1:1 ratio between members of treatment groups compared to the placebo group, 15,000 participants from each of those trials who were assigned to the placebo condition are offered and approved vaccine.”

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Mass vaccination program

The NAP predicts that a FDA-approved vaccine will be distributed in four phases with health-care workers and vulnerable Americans, such as the elderly and those with underlying, co-morbid health conditions, receiving it first. Health officials are optimistic that at least one safe and effective vaccine will be available by the end of the year and possibly more than one by the start of next year. Phase I and Phase II would cover between 40-50% of the U.S. population in a free, mass vaccination program although it is estimated that a third of the populace could decline to take part.

See also

First case of Covid-19 reinfection reported in US

South Africa hosts phase 2 Covid-19 vaccine trials

Oxford Covid-19 vaccine final trials to be held in 17 Indian hospitals