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The coronavirus is spreading around the world, and it has been declared a global emergency by the World Health Organization.

Right now there are no approved vaccines to protect the body against the disease it causes, Covid-19.

However, in recent weeks there have been several major vaccine breakthroughs.

US pharmaceutical company, Moderna, announced it has produced a vaccine that is 95% effective in protecting people against coronavirus.

It's the second company to announce successful trial results, and comes a week after another trial of a vaccine offered 90% protection from the virus.

And, early results from the second phase of vaccine trials at the University of Oxford have shown a strong immune response in adults in their 60s and 70s, raising hopes that it can protect age groups most at risk from the virus.

More tests need to be done before any of these vaccines can be approved for use.

So, what is a vaccine and how does it work?

A vaccination is a treatment which makes the body stronger against a particular infection, by actually introducing a tiny bit of the virus or bacteria into your body.

It's not enough to give you the disease, but it helps the body's defences - the immune system - to recognise the virus as an invader and learn how to fight it in the future.

Each virus has a unique genetic code, containing information which helps scientists find out where the virus probably came from, how it might change as it spreads, and how to protect people against it.

From the genetic code they can then design a vaccine, which can be created in a science lab.

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Following a vaccination, a person can become immune (resistant) to the specific disease. This immunity gives protection against illness in an individual.

But also helps protects others too, something called herd immunity.

That's because, if the majority of the population is vaccinated against serious diseases, then even those who haven't had the vaccine are much less likely to come into contact with the virus.

About 80 teams of scientists around the world are working hard to research possible vaccines to prevent the virus.

Clinical trials have begun, which are scientific tests on animals and humans to check if the vaccines are safe to use.

The first human trial for a vaccine was announced in March by scientists in Seattle, USA.

The first human trial in Europe started in Oxford, England, with more than 800 people taking part.

Half of the those being monitored will be given the Covid-19 vaccine whilst the rest will get another vaccine, which protects against meningitis but not coronavirus.

This will allow scientists to compare the two sets of results to work out if the coronavirus vaccine is effective.

Different countries and scientists have been trying to come up with a vaccine for Covid-19 which means there are lots of trials going on at the moment.

Scientists believe that many types of vaccines will be needed to end the pandemic.

A vaccine would normally take years, if not decades, to develop. But medical researchers, working hard across the world, hope to produce a vaccine for coronavirus in just a few months.

If scientists can find a vaccine for the virus, the next step will be working out how large amounts of it can be produced and distributed to people all around the world. This will be a massive challenge in itself.

This is a very quick turnaround for a vaccine, and if it is a success, will be a huge scientific achievement.

As well as working on vaccines, scientists all over the word are also looking for other ways to tackle coronavirus or Covid-19, the illness that it causes.

In some cases, while waiting for a vaccine, viruses or related illnesses can be treated with existing drugs - for example medicines used for other respiratory diseases or even totally unrelated illnesses.

So experts are also experimenting in labs to see if an already available drug, or a combination of drugs, might also help treat patients.