As the world scrambles to find a vaccine to COVID-19, Bill Gates has opened up on what he thinks about anti-vaxxers, conspiracy theories and the use of hydroxychloroquine.

The Microsoft co-founder and philanthropist addressed the topics in an interview with Bloomberg published this week.

"It’s ironic that people are questioning vaccines and we’re actually having to say, 'Oh, my God, how else can you get out of a tragic pandemic?'," he told Bloomberg when asked about the anti-vax movement.

Gates has pledged to give more than US$350 million (NZ$534m) through the Bill and Melinda Gates Foundation to fight the coronavirus. However, viral conspiracy theories have run rampant in recent months, claiming, for example, the billionaire planned to use microchip implants which would contain "digital certificates" showing who had been tested for COVID-19 and who had been vaccinated.

The theories have been debunked countless times, though according to a least one survey from earlier this year 28 percent of adults in the US believed Gates wanted to use the vaccine to track people. 

Gates, of course, denies the claims. 

"It’s strange," he told Bloomberg. 

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"They take the fact that I’m involved with vaccines and they just reverse it, so instead of giving money to save lives, I’m making money to get rid of lives. If that stops people from taking a vaccine or looking at the latest data about wearing a mask, then it’s a big problem."

He also spoke about hydroxychloroquine, which US President Donald Trump has encouraged people to take despite his own FDA advising against it due to the risk of serious side effects such as causing heart rhythm problems.

Gates said although "in the test tube, hydroxychloroquine looked good" there are many other good therapeutic drugs on the way proven to work without severe side effects.

Gates predicted the innovations in therapeutic drugs would "cut the death rate" of COVID-19 but the virus would only be truly defeated "through the spread of natural infections and the vaccine giving us herd immunity".

All going well, he predicted, the virus could be brought under control in rich countries by the first half of next year.