With the world heading towards its third month in lockdown, hopes are increasingly resting on the rapid development of a coronavirus vaccine for life to return to normal.

The UK government has said it will throw ‘everything it can’ at work to discover a jab and last week pledged another £84 million to research projects at Oxford University and Imperial College London.

There have been some positive signs of progress this week. Oxford professors said work to manufacture doses of their vaccine in Autumn is ‘still on track’, with scientists now ramping up human trials.

The study is considered to be one of the world’s frontrunners, with a deal already in place to manufacture 30 million doses by September if trials prove successful.

But with the summer deadline approaching, ministers and their advisers have become noticeably more cautious, warning an effective vaccine may never be found.

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Why might a coronavirus vaccine fail?

Covid-19 is a new strain of coronavirus and scientists still know very little about it

Vaccine research went ahead for two earlier strains of coronavirus which caused lethal outbreaks, Sars and Mers, but the treatment was never licensed.

Though these previous studies will help, a chief concern is that most coronaviruses do not guarantee immunity.

About a quarter of common colds are caused by human coronaviruses, but the antibodies that build up to protect the immune system don’t last long, meaning people can easily contract a cold again.  

Studies have shown that most people who recover Covid-19 develop some antibodies, but it is not known how much protection they offer or how long they last.

Researchers from the University of Oxford analysed blood from recovered patients and found that levels of IgG antibodies, which is responsible for longer-lasting immunity, rose steeply in the first month of infection but then began to fall.

David States, chief medical officer of the US health technology company Angstrom Bio, spelt out the challenges in a thread on Twitter last week.

He then pointed to the Oxford study, adding: ‘This is consistent with the other human coronaviruses. They induce an immune response, but it tends to fade so the same virus can reinfect us a year or two later.’

He added: ‘The problem is that Sars-Cov-2 is a highly contagious virus.That means a vaccine will need to be quite effective if it’s going to stop the spread.

‘The polio, measles and smallpox vaccines are really remarkable medicines inducing high level long-lasting immunity, but not all vaccines work so well.’

On a more positive note, there are indications that Covid-19 will prove more stable than influenza and HIV viruses, which constantly mutate. The rapid evolution of HIV is one of the main reasons we have no vaccine for the disease.

How long do vaccines usually take?

The ideal vaccine protects against infection and prevents its spread, but they can take years to develop, and in many cases they are never found.

The fastest vaccine that was ever developed was for the mumps, which took four years.

There is no vaccine for HIV more that 30 years after scientists isolated it and a vaccine for the dengue fever, which was identified in 1943, was only approved last year.

Chief Medical Officer Chris Whitty has said a coronavirus vaccine is a year away at the least and that would be pushing it. His US counterpart, Anthony Fauci, suggested 12-18 months is a more realistic minimum.

Does that mean there will never be a coronavirus vaccine?

 It may be possible to create a vaccine that reduces the symptoms of Covid-19 even if it does not prevent the disease itself.

Professor Chris Whitty said in a lecture last week that vaccines can be therapeutic as well as preventative.

Another big positive is unprecedented levels of funding and research going into the race to find a Covid-19 vaccine.

World leaders have pledged over £6 billion to find a vaccine. About 80 groups around the world are undertaking research and six have progressed into human trials.

What stage are the coronavirus human trials at?

Oxford scientists said they will know in about six weeks if their vaccine has been successful.

Earlier this week it emerged that six monkeys used in the trial were found to have the same amount of Covid-19 in their noses as three non-vaccinated monkeys, suggesting those who are vaccinated could still be infected and pass the virus on to others.

However, the scientists defended the treatment, claiming that it achieves its primary purpose which is to protect vaccinated individuals against the most severe effects of the virus.

The study found that the vaccinated moneys did not sustain any lung damage or catch pneumonia when exposed to the virus, unlike their non-vaccinated primates. 

Meanwhile, scientists in China say a coronavirus vaccine trialled in 108 healthy volunteers triggered an immune response in the participants.

In the US, country’s leading infectious disease specialist Dr Fauci expressed ‘cautious optimism’ about early results from a vaccine clinical trial published this week.

The vaccine manufacturer, Moderna, said results showed the jab stimulated an immune response  against coronavirus, meaning their bodies produced antibodies to fight it.

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