One of 10 possible COVID-19 vaccine candidates in late-stage testing around the world is showing early signs of success.

Pfizer says preliminary data from trials shows its vaccine may be 90 per cent effective, but there are still multiple questions that need to be answered.

They include how long the vaccine's effects last and if it also protects older people as well as younger people.

Ottawa has signed a procurement deal with Pfizer for 20-million doses of the vaccine.

Stock markets skyrocket this morning

The declaration of Joe Biden as US President-elect and the news of early data suggesting the effectiveness of Pfizer's COVID-19 vaccine has seen stock markets skyrocket this morning.

Markets were already sharply higher on the US election result when Pfizer said that data shows its vaccine may be 90 per cent effective at preventing COVID-19, although the results are only preliminary.

Global economic recovery depends on controlling the pandemic, and European markets surged at the news from the drugmaker, while Dow futures jumped 4.2 per cent higher and those for the S&P 500 rose 3.1 per cent.