While a global race underway to develop a human ready vaccine for the Covid-19 continues, there are several things that will determine how and when it could be developed.

How far away is a Coronavirus vaccine?

One of Australia’s most eminent vaccine developers says there may never be a vaccine against COVID-19 for some very good reasons.

Professor Ian Frazer, the immunologist who co-invented the human papilloma virus (HPV) vaccine which prevents cervical cancer, said a coronavirus vaccine was “tricky”.

He told news.com.au that although 100 different teams around the world were testing for vaccines, medical scientists did not have a model of how to attack the virus.

The professor of medicine at Queensland University, which is testing for its own COVID-19 vaccine, said immunisation against coronavirus was similar to immunising against the common cold.

“It is tricky, vaccines for upper respiratory tract diseases, because the virus lands on the outside of you,” Prof Frazer said.

“Think of us as a football, with the skin and respiratory tract on the outside of the football and the lungs are where the outside interfaces with the inside.

“The place where the virus lands is outside us and it tries to infect the cells within us.

“Our immune system is inside of us. When it lands inside our lungs it tries to infect our cells and succeeds. Our immune system goes to fight the virus and that’s why people get sick.

“If the immune system turns on too strong it can cause damage to the lungs.

“The wrong vaccine could make things worse so we have to be very selective about what part of the virus we want to attack.

“If you immunise someone with a vaccine, it goes inside and makes an immune response within you.

“What you want is an immune response to migrate out to where the virus lands.

“There is no vaccine against the common cold.”

Prof Frazer said that with flu, the immune response inside a person’s body didn’t occur until the flu virus gets inside them.

“We tried to deliver a vaccine to the lungs with the Flu Mist which you snuffed up your nose, delivering the vaccine to the place where you need an immune response, but it didn’t work terribly well,” he said.

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“Coronavirus doesn’t get into you, it stays on the surface cells in your lungs. All these flu viruses get into you, so the body can fight and makes T cells.

“This virus doesn’t kill the cells, it makes them sick. At the moment we don’t know how to make a coronavirus vaccine work.

“That’s why there are 100 vaccines under testing using every conceivable approach.

“We don’t know if any of them will work.”

Prof Frazer said a vaccine for the 2003 SARS (severe acute respiratory syndrome) outbreak was never successfully developed and then the virus burnt out.

SARS broke out in China and didn’t spread as far, partly because overseas travel by the Chinese population was not as great 17 years ago as it is today.

But, Prof Frazer said, it also had diluted potency as it went from host to host.

“As it passed from animal to the first human and then through the second human, as it passed through every human it got a little less good at infecting people,” he said.

“The virus attenuated itself; it got less powerful.

“It may well be the same with this virus. It’s not very effective in making us sick. It may become less effective.

“We are now mapping it as it goes and changes are occurring in its genetic make-up, small changes.

“Changes to it in China led to the virus becoming less virulent or sick-making.

“At the moment it’s not passing through a lot of people in Australia.”

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Prof Frazer said coronavirus was less infectious and not as deadly as MERS, the Middle Eastern Respiratory Syndrome or camel flu which broke out in South Korea in 2015.

“MERS … was very efficient infecting and making people sick,” he said.

“One person who went to South Korea from the Middle East infected 170 people and a third of those died.

“He went through four hospitals before he was diagnosed, but in South Korea they were very effective with contact tracing.

“MERS is much nastier … than coronavirus.”

Prof Frazer explained the annual vaccines prepared against the winter flu by the Commonwealth Serum Laboratories (CSL) were not entirely effective.

Each year CSL “takes about a quarter of Australia’s egg supply to make the vaccine,” he said.

“We purify the protein parts of the virus out of the eggs and make the vaccine out of that.

“But it’s not 100 per cent effective at all … for older people (because) as your immune system gets weaker as you get older.

“With measles you are protected against it for life. The vaccine kills any virus that gets into your blood.

“We don’t have a mode that works against other coronaviruses.”

Prof Frazer, who is currently developing vaccines for cancer, is working with a team of medical scientists on a trial for a coronavirus treatment drug.

The intervention drug’s purpose is to dampen down the inflammatory response in high-risk coronavirus patients.

He said for 99 per cent of people who got coronavirus it was a trivial illness, but that was not the case for those in the vulnerable categories.

candace.sutton@news.com.au