The researchers surveyed 28 experts working in vaccinology for the paper. The respondents had an average of 25 years of experience in the field.
[The] forecasts on vaccine development [...] were generally less optimistic than the timeline of early 2021 offered by US public officials.
Jonathan Kimmelman, McGill University Biomedical Ethics Unit Director
They also predicted that the latest that a vaccine would be available is summer 2022.
Many of the experts believed that it would take many tries before an "effective vaccine" is available.
"The experts we surveyed believe that there is [...] a 4 in 10 chance that the first large field study will not report efficacy," said Patrick Kane, the paper's lead author and a postdoctoral fellow at McGill.
On Tuesday, Premier François Legault said there could be more outbreaks before a vaccine is introduced.
"As long as we don't have a vaccine," he said, "there's a possibility for two waves, three waves, four waves."