WASHINGTON (BLOOMBERG) - Microsoft Corp founder and philanthropist Bill Gates urged the United States to take a more global approach in dealing with the coronavirus pandemic, saying while the nation leads in research, "we've only taken care of ourselves" in producing and procuring a vaccine.

Mr Gates said he has encouraged congressional lawmakers to consider adding US$8 billion (S$11 billion) to the economic relief Bill currently being debated that will be devoted to helping less-developed nations procure an eventual vaccine to stop the spread of Covid-19.

"We're trying to make sure we can end it not just in the rich countries," Mr Gates said in an interview with Bloomberg News on Tuesday.

The Bill & Melinda Gates Foundation has pledged more than US$250 million towards Covid-19 research.

Much of that money has gone towards funding not only research, but also manufacturing capacity that will help a vaccine be distributed globally.

In particular, Mr Gates said, he has funded vaccine development efforts by AstraZeneca, Johnson & Johnson and Novavax, which on Tuesday reported promising early trial data.

"Those are the ones most scalable and low-cost," he added.

Around the world, there are well over a hundred vaccines in development, with more than two dozen in human clinical trials.

As it becomes clear that vaccines are the best hope for reining in the pandemic and allowing countries to fully reopen their economies, nations are scrambling to get access to supplies.

Mr Gates joins many others expressing growing concerns over "vaccine nationalism" in which one nation prioritises producing and stockpiling vaccines for itself.

His foundation has invested in an entire portfolio of potential Covid-19 therapies and vaccines, including a vaccine being developed in South Korea.

'STOP-GAP VACCINE'

He believes a vaccine will likely be approved by the beginning of 2021, though that may be a "stop-gap" primarily available to wealthier nations.

More effective vaccines, Mr Gates said, may take longer to develop.

"The initial vaccine, in terms of its effectiveness against sickness and transmission, won't be ideal and may not have a long duration," he said.

In the meantime, he said he is optimistic that many therapies in development to treat the virus may help significantly reduce the death rate of the virus.

"Innovation in diagnostics, therapeutics and vaccines will get us largely out of this by the end of 2021," he said.

"The true end comes when between natural infection and a vaccine, we have this herd immunity."