The company hopes to begin clinical trials on its vaccine by September and to begin manufacturing the vaccine – if it is successful – early next year. It could ship the one billion vaccines within 18 months. Dr Stoffels said Western nations should be able to survive the worst of the pandemic and his greatest concern was the impact on south-east Asia, Africa and South America. He urged governments to listen to their scientists, lock down their cities and enforce strict social distancing to control the spread of the disease. "I am less concerned about Western countries, countries with very good healthcare infrastructure. They can probably get through this. If this is now going through countries with limited or no healthcare infrastructure, it's going to be very bad," he said "I think Africa has limited healthcare infrastructure, especially speciality healthcare infrastructure. South America might have to deal with a big thing, south-east Asia could be a big, big risk.

Loading "Every country, every government, every governor of a region should do the right thing to limit the epidemic to where it is, and make sure there are lockdowns, that people are not travelling from these zones to other regions." He urged governments around the world to follow their scientists' directions because "all the rest is guessing". The warning stands in sharp contrast to Indonesian president Joko Widodo's decision not to officially ban the annual mudik, or return home, for the Idul Fitri religious holiday in May and to stop short of a full lockdown. Across south-east Asia Singapore, Thailand, Vietnam and Malaysia have thus far managed to limit the spread of the coronavirus and have implemented robust testing regimes, but countries such as Indonesia, the Philippines, Myanmar and Laos are lagging badly.

Last year, nearly 20 million people travelled back to their villages across Indonesia from the country's sprawling major cities, such as the capital Jakarta, and regional governors and experts have been demanding Joko ban the mudik in 2020, warning of a potentially disastrous spread of the virus around Indonesia. Indonesia's government has instead urged people to stay at home, cut subsidised travel for the least well-off and has started axing inter-city train and bus services. Johnson & Johnson's chief scientific officer Paul Stoffels talks to scientists at the company's Janssen Vaccines facility in Leiden, Holland. J&J's plan to bring online up to four factories that can manufacture a vaccine before the vaccine has even been tested and proven to work is akin to a car-maker readying four assembly lines to make a car before the design of that car has been finalised. Dr Stoffels said that locations in China, Japan, South Korea, Taiwan and Singapore were being considered as potential sites where the vaccine could be manufactured.

Australia's CSL could also be a contender to make the vaccine given its expertise, although J&J had not yet spoken to the Australian firm about whether it would have the capacity do this. There are at least 20 efforts underway around the world to create a vaccine to combat the coronavirus, including four in Australia. Asked what was unique about J&J's attempts to find a vaccine, Dr Stoffels said the company had extensive experience in working on vaccines for HIV, the common flu, the Zika virus and Ebola. J&J also had the manufacturing capacity that other efforts may lack. "We always feared that one day this could happen in the world," he said. "We always hoped we could regionally control it."