Bill Gates has said the world could need as many as 14 billion vaccine doses in order to stop the spread of the novel coronavirus.

Writing recently at his blog, GatesNotes, Mr. Gates insisted that it will take months, if not years, to find a vaccine for the world’s population, and that creating 7 billion doses may not be sufficient if achieving immunity requires a multi-dose vaccine.

“It’ll take months—or even years—to create 7 billion doses (or possibly 14 billion, if it’s a multi-dose vaccine), and we should start distributing them as soon as the first batch is ready to go,” he wrote.

The multi-billionaire insisted that once healthcare workers are vaccinated, people from low-income countries should be the first to receive the vaccine, despite lower death rates per million being reported in poorer countries compared with developed nations in Europe and North America.

“Most people agree that health workers should get the vaccine first. But who gets it next? Older people? Teachers? Workers in essential jobs?,” he asks.

“I think that low-income countries should be some of the first to receive it, because people will be at a much higher risk of dying in those places. COVID-19 will spread much quicker in poor countries because measures like physical distancing are harder to enact.”

“More people have poor underlying health that makes them more vulnerable to complications, and weak health systems will make it harder for them to receive the care they need. Getting the vaccine out in low-income countries could save millions of lives.”

Expressing hope that the WHO and national health authorities will help to distribute the vaccine globally, Gates said “we already have an organization with expertise about how to do this in Gavi, the Vaccine Alliance.”

The Bill and Melinda Gates Foundation has a seat on the board of Gavi, along with representatives from the vaccine industry and key organisations such as the Word Bank and WHO.

Discussing a possible Covid-19 vaccine, Gates said that it’s safety cannot be guaranteed and that there may be problems similar to that experienced with the small-pox vaccine, where “one out of every three people had side effects bad enough to keep them home from school or work.”

He also conceded that “a small—but not insignificant—number developed more serious reactions.”

“The smallpox vaccine was far from perfect, but it got the job done. The COVID-19 vaccine might be similar. If we were designing the perfect vaccine, we’d want it to be completely safe and 100 percent effective. It should be a single dose that gives you lifelong protection, and it should be easy to store and transport. I hope the COVID-19 vaccine has all of those qualities, but given the timeline we’re on, it may not,” the Microsoft founder admitted.

In terms of efficacy in stopping the spread of Covid-19, a vaccine that is 70 percent effective would be enough to create herd immunity according to Gates.

“I suspect a vaccine that is at least 70 percent effective will be enough to stop the outbreak. A 60 percent effective vaccine is useable, but we might still see some localized outbreaks. Anything under 60 percent is unlikely to create enough herd immunity to stop the virus.”

Criticism has been leveled at the Gates Foundation however as significant studies begin to indicate widespread immunity is possible without a vaccine, with countries like Sweden appearing to be ahead of the curve in that regard.

The Swedish ambassador to the US recently said she expects Stockholm to have developed herd immunity to the virus by the end of May, whilst studies conducted by Stanford, Oxford and the State of New York suggest antibodies are already present in significant swathes of certain populations.

Meanwhile, South Korean scientists have went some way to allaying fears about re-infections, citing testing faults as the reason 292 former carriers were led to believe the virus had reactivated or they had contracted a new strain.

Disease experts now believe fragments of the virus can remain for months after a person has recovered and developed antibodies, which would cause false positives in testing results conducted after the person is no longer infectious.