But the Microsoft co-founder warned that this is the "best case" scenario, as it still remains uncertain whether any vaccines will work.
The 64-year-old, who in April stepped down from the board of the Redmond-based tech giant he founded in 1975, told The Wall Street Journal there were still some hurdles to clear in the race for a vaccine for COVID-19.
"Now the capacity will take time to ramp up," said Mr Gates.
"And so the allocation within the US, and between the US and other countries, will be a very top point of contention."
The race for a vaccine is being led by AstraZeneca in collaboration with Oxford University, while another promising effort is being developed by Pfizer and BioNTech.
Both are hoping to be the first to gain regulatory approval in the West.
The head of the World Health Organisation (WHO), Tedros Adhanom Ghebreyesus, said on Tuesday a vaccine may be ready by the end of the year - earlier than suggested by the UK's chief scientific adviser Sir Patrick Vallance.
In the UK, any vaccine is expected to be rolled out based on who is most vulnerable to coronavirus and it has been suggested that less than half of the population will be vaccinated.
Mr Gates' charity - the Bill & Melinda Gates Foundation - has recently signed an agreement with 16 pharmaceutical companies to speed up the process of manufacturing and distributing a vaccine.
The bid to find, approve and deliver a vaccine has been moving at unprecedented speed.
Russia is pushing ahead with its COVID-19 vaccine, with mass public vaccinations taking place alongside the main human trials - prompting concerns the country is prioritising national prestige over health and safety.
Mr Gates has said his foundation - to which he has donated $36bn of his own personal fortune - is "talking with Russia and China" about their respective vaccination programmes.
But he is concerned that that their lack of a well-respected Phase 3 study - covering thousands of people to look at the level of protection a vaccine would provide for society in general - could limit their appeal internationally.
"None of their vaccines are in a Phase 3 trial with a highly-regarded regulator overseeing that trial," said Mr Gates.
He added: "The Western companies are further ahead on doing these Phase 3 studies. So if those come out well and they're offered at low cost, I doubt there'll be a lot of Russian or Chinese vaccines going outside of those countries."
Mr Gates also paid tribute to the countries he thought had best balanced the health and economic challenges posed by the pandemic, citing South Korea and Australia.
He has not previously offered direct criticism of any one country's response, but did hit out at Donald Trump over his decision to withdraw US funding for the WHO.