There are currently over 100 coronavirus (Covid-19) vaccine candidates being developed worldwide, aided by US$2bn donated by the Bill & Melinda Gates Foundation.

Four of these are leading the race.

READ: Coronavirus: what’s happening in the labs of pharma companies worldwide

The Jenner Institute at Oxford University made the headlines this week as it could have a few million doses ready as early as September.

A US study showed that monkeys which were administered the Oxford vaccine survived exposure to the virus and were healthy four weeks after receiving the jab.

Although immunity in monkeys does not necessarily ensure the same will happen in humans, the results are encouraging as the team prepare to test 6,000 people by the end of May.

Oxford Biomedica PLC (LON:OXB), a biotech firm selected to take part in the vaccine production, is preparing to scale up commercial manufacturing.

Ironically, flattening the curve of coronavirus cases in the UK comes as a challenge.

“We’re the only people in the country who want the number of new infections to stay up for another few weeks, so we can test our vaccine,” Prof. Adrian Hill, the Jenner Institute’s director, told the New York Times.

Researchers are not allowed to infect test participants with a serious disease: the only way to prove whether a vaccine is successful is to have trials in an area where the virus is widespread.

If the UK manages to reduce the number of cases, people who were administered a placebo may have fewer chances of being infected, so the study would have to move elsewhere.

Meanwhile, experts say having multiple candidates can help in identifying what works for different sets of the population.

One of the fastest out of the starting blocks was biotech company Moderna Inc (NASDAQ:MRNA), which developed a candidate in only 63 days and entered trials in March.

If ready it could be available to some professional categories by autumn 2020.

According to Adam Barker, an analyst at Shore Capital, another two candidates to watch are being developed by Johnson & Johnson (NYSE:JNJ) and the partnership of BioNTech and Pfizer Inc. (NYSE:PFE).

J&J selected a candidate in March, after two months of research, pencilling in human clinical studies by September.

The first batches of the jab could be available for emergency use authorisation in early 2021.

Competitor Pfizer teamed up with BioNTech (NASDAQ:BNTX) to push several candidates into trials, and received the green light by the German government last week to start on 200 healthy volunteers.

Analysts at Shore Capital said the pace of these efforts has been “incredibly impressive”, although it will take time to see results.

“We still believe that a widely distributed vaccine won’t be available for at least twelve months given the need for wider testing, quality control and then large-scale manufacture and distribution,” the broker commented.