TORONTO -- Although companies attempting to produce a COVID-19 vaccine are increasingly saying it is likely that they will not complete the testing process until 2021, the head of the World Health Organization says there is still a chance a vaccine could be ready sooner than that.

"We need vaccines – and there is hope that, by the end of this year, we may have a vaccine," WHO Director-General Dr. Tedros Adhanom Ghebreyesus said Tuesday.

Tedros did not elaborate on that comment, which he made at the end of a special meeting of the WHO's executive board.

Many vaccine candidates are in Phase 3 testing, the final stage of human trials. The WHO's website lists 10 potential COVID-19 vaccines at this step as of Oct. 2.

However, the major manufacturers' public comments have largely suggested that they do not expect to have any vaccine ready for distribution until the end of next year.

The most notable exception has been the Russian-developed Sputnik V, which has been registered and given to cabinet-level officials in that country even though testing is still ongoing. Russian authorities have said that they could start mass vaccinations this fall. Western leaders appear skeptical, as none have publicly backed Sputnik V.

Speaking from WHO headquarters in Switzerland, Tedros also urged world leaders to work together on vaccine distribution, saying governmental buy-in to sending any vaccine where it is most needed will be "crucial" in halting the pandemic.

"The most important tool is political commitment from our leaders, especially in the equitable distribution of the vaccines," he said.

The WHO has set up a fund to help 92 poor countries pay for a vaccine, in exchange for early access for citizens of investing nations. Following criticism of Canada's seeming lack of interest in the COVAX fund, Prime Minister Justin Trudeau announced a $220-million contribution last week.

The United States, China and Russia have not committed to having any involvement in COVAX. Not all of the front-running vaccine candidates are part of the project either; it does not cover Sputnik V, potential vaccines from China's CanSino, Sinovac and SinoPharm, or the efforts by pharma giants Pfizer and Johnson & Johnson, among others.

Canada has also signed separate deals to ensure access to six potential vaccines, should they be approved for use by Health Canada.