The world is awaiting a covid-19 vaccine with baited breath, but how close are we? Well, there’s good news and bad news. The good news? Scientists are working flat out to develop a vaccine. The bad news, though, is that vaccine development is far from straightforward and we could be waiting a long time before a remedy is found and made easily accessible to all corners of the world.

Vaccines for dummies: A vaccine stimulates the body’s immune system by exposing it to an agent that shares similarities with a disease-causing pathogen. This causes the immune system to produce antibodies, preparing it to fight the disease if it contracts it in the future. To achieve this scientists need to find a viable antigen, which could be obtained from other strains of the virus.

Wait, what’s an antigen? This is a weakened strain of the virus that the body’s immune system can recognize without the person actually becoming infected. Vaccines also include what’s known as adjuvants — an agent that heightens the reaction of the immune system to the antigen.

So what’s the hold-up? Any potential vaccine must be tested in several phases. First, studies are conducted on animals. Then, three stages of clinical trials are performed on healthy patients before regulators can give the green light to proceed. This process often takes 10 to 15 years, but US immunologist and public health adviser Anthony Fauci believes that a vaccine could be developed within the next year-and-a-half (watch, runtime: 1:34).

There are currently 70 potential covid-19 vaccines in different phases of production — including three that are already being tested on humans — according to the World Health Organization (pdf). The most promising appears to be an experimental vaccine developed by Hong Kong’s CanSino Biologics and the Beijing Institute of Biotechnology. Big pharma is also getting in on the hunt, with giants Pfizer, Inovio and Sanofi all in the early stages of vaccine development.