Coronavirus is spreading around the world, but there are still no vaccines to protect the body against the disease it causes, Covid-19.
Medical researchers are working hard to change that.
The virus spreads easily and the majority of the world’s population is still vulnerable to it. A vaccine would provide some protection by training people’s immune systems to fight the virus so they should not become sick.
This would allow lockdowns to be lifted more safely, and social distancing to be relaxed.
Research is happening at breakneck speed. About 80 groups around the world are researching vaccines and some are now entering clinical trials.
However, no-one know how effective any of these vaccines will be.
A vaccine would normally take years, if not decades, to develop. Researchers hope to achieve the same amount of work in only a few months.
Most experts think a vaccine is likely to become available by mid-2021, about 12-18 months after the new virus, known officially as Sars-CoV-2, first emerged.
That would be a huge scientific feat and there are no guarantees it will work.
Four coronaviruses already circulate in human beings. They cause common cold symptoms and we don’t have vaccines for any of them.
Multiple research groups have designed potential vaccines, however, there is much more work to do.
Lockdowns could make this process slower. If fewer people are infected, it will take longer to know whether a vaccine actually works.
The idea of giving people the vaccine and then deliberately infecting them (known as a challenge study) would give quicker answers, but is seen as too dangerous while there is no known treatment.
It is hard to know without knowing how effective the vaccine is going to be.
It is thought that 60-70% of people needed to be immune to the virus in order to stop it spreading easily (known as herd immunity).
But that would be billions of people around the world if the vaccine worked perfectly.