As of July 2020, the COVID-19 pandemic has resulted in close to 12 million infections and more than 500,000 deaths globally.1 Rapid development of a SARS-CoV-2 vaccine is a public health priority.
Because of the unprecedented nature of research efforts, historic experience with vaccine development may not provide accurate estimates for SARS-CoV-2 vaccine development timelines and outcomes. Expert elicitation and aggregation synthesize diverse insights that are spread across expert communities, and offer an alternative way to estimate when vaccines will be available.2,3
We identified experts through the contact network of the vaccinologist author BJW and corresponding author searches for review articles on vaccinology in highly cited medical journals. We solicited experts for participation by e-mail on the week of June 21st and a second time on the week of June 28th.
We asked for timeline forecasts for three vaccine development milestones: (1) a field study enrolling at least 5000 participants reporting results, (2) a vaccine being available to those at highest risk from the virus in the USA and/or Canada, and (3) a vaccine being available to the general public in the USA and/or Canada. Experts provided best, soonest, and latest estimates for when each milestone would occur. We also asked for probability estimates of two setbacks: (1) the first vaccine widely deployed in the USA and/or Canada receiving a boxed warning from the FDA to highlight serious or life-threatening adverse reactions and (2) the first large field trial in the USA and/or Canada reporting a null or negative result on an efficacy endpoint. We calculated the median and interquartile ranges of the forecasts to measure both the consensus and range of opinions.
Finally, our survey collected basic demographic information and two Likert scale questions measuring comfort answering questions about the US and Canadian health care system and the extent to which experts think the pace of COVID-19 research will lead to more errors in the vaccine development process.
Our sample consisted of 28 experts with 25 median years of experience working with vaccines (range 8–42); 20 worked in academia, 6 in industry, and 2 in government. Participants were mostly based in Canada (20) and the USA (6); participants worked in academia (20), industry (6), and public health (2). Participants indicated they were very comfortable (46% or 13/28) or somewhat comfortable (46% or 13/28) answering questions about vaccine development in the USA or Canada.
The median and interquartile range of forecasters’ best guesses, soonest occurrence, and latest occurrence for each milestone are indicated in Figure 1. See Figure 2 for histograms of setback probabilities.
Experts were split on whether the pace of COVID-19 research is increasing the potential for errors; 53% (15/28) agreed, 14% (4/28) were neutral, and 32% (9/28) disagreed.
Experts in our survey offered forecasts on vaccine development that were generally less optimistic than the timeline of early 2021 offered by US public officials.4 Experts seem to believe that a publicly available vaccine next summer is the best case scenario with the possibility that it may take until 2022. In addition, the median probabilities that a vaccine would receive a warning label and that a field study might not report positive outcomes were 30% and 40% respectively.
Our survey has important limitations. First, our sample is predominantly Canadian, though it is worth noting Canada has a productive vaccine development enterprise.5 Second, our elicitation approach was relatively simple to minimize survey burden for vaccine developers. Nevertheless, our estimates provide a more complete picture of expert belief than single point estimates or media quotes from individuals.
Coronavirus Disease (COVID-19) Situation Reports. Accessed July 15, 2020. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports
Morgan MG. Use (and abuse) of expert elicitation in support of decision making for public policy. Proc Natl Acad Sci U S A. 2014;111(20):7176-7184. https://doi.org/10.1073/pnas.1319946111
Davis-Stober C, Budescu D, Dana J, Broomell S. When is a crowd wise? Decision 2014; 1. https://doi.org/10.1037/dec0000004
Anthony Fauci on Covid-19 reopenings, vaccines, and “warp speed.” STAT. Published June 1, 2020. Accessed July 15, 2020. https://www.statnews.com/2020/06/01/anthony-fauci-on-covid-19-reopenings-vaccines-and-moving-at-warp-speed/
Wolf J, Bruno S, Eichberg M, et al. Applying lessons from the Ebola vaccine experience for SARS-CoV-2 and other epidemic pathogens. Npj Vaccines 2020;5(1):1-5. https://doi.org/10.1038/s41541-020-0204-7
This project was funded by a McGill Interdisciplinary Initiative in Infection and Immunity research grant.
Conflict of Interest
PBK, SBB, HM, AM, and JK declare no conflicts of interest. BJW serves as medical officer for Medicago Inc., a pre-clinical biotechnology company with a candidate vaccine for SARS-COV-2. JP has received consulting/honoraria fees from AbbVie, Cepheid and Seegene, and Jannsen and research grant funding outside of the current work from AbbVie, BD Diagnostics, Sanofi Pasteur, and MedImmune.
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Kane, P.B., Moyer, H., MacPherson, A. et al. Expert Forecasts of COVID-19 Vaccine Development Timelines. J GEN INTERN MED 35, 3753–3755 (2020). https://doi.org/10.1007/s11606-020-06244-9