Johnson & Johnson’s COVID-19 vaccine has one big advantage over the two options currently on offer to Australia — it doesn’t need a booster shot.

Key points:

  • The Johnson & Johnson vaccine is a viral vector vaccine
  • Scientists are examining if the jab will have a higher efficacy rate after two doses
  • Johnson & Johnson has submitted an application to the TGA for the provisional registration

The US Food and Drug Administration authorised the Johnson & Johnson jab for emergency use on February 27, making it the United States’ third regulator-approved coronavirus vaccine.

“It’s a gamechanger I think, to have a one-dose vaccine that works almost as well as a two-dose vaccine,” La Trobe University associate professor in epidemiology Hassan Vally said.

An interim analysis of Johnson & Johnson’s phase three trial (which involved more than 40,000 volunteers) showed the vaccine offered 66 per cent protection against moderate COVID-19 disease and 85 per cent protection against severe disease.

How does that compare to the two vaccines approved in Australia?

The Pfizer vaccine is 95 per cent effective at preventing symptomatic COVID-19 after two doses.

And AstraZeneca’s efficacy ranges between 62 and 90 per cent, depending on the dosage amount and time between doses.

So why does the Johnson & Johnson option only need one dose to be effective?

And will it be offered to Australians?

Here’s what we know so far.

How the Johnson & Johnson vaccine works

The Johnson & Johnson vaccine, similar to the AstraZeneca option, is a viral vector vaccine which use an adenovirus to deliver DNA into our cells,

DNA is not as fragile as the mRNA in the Pfizer vaccine, which is why both viral vector jabs can be stored in a fridge (and the Pfizer must be kept below minus-70 degrees Celsius),

Neither of these adenoviruses can replicate in human cells or cause disease, so they are harmless after being injected.

AstraZeneca does this using a non-infectious chimpanzee adenovirus, whereas Johnson & Johnson uses a human virus called adenovirus 26.

Dr Vally said the Johnson & Johnson candidate used “traditional” technology to prompt the body’s immune response.

“It’s the more traditional way you design a vaccine where you introduce the antigen, or the protein, directly into the body and then you allow the immune system to mount a response against that antigen,” he said.

University of Sydney associate professor Nicholas Wood explained that within the adenovirus 26, there was a DNA code for the “all-important spike protein”.

“When [the Johnson & Johnson vaccine] is injected, the adenovirus infects the cells, the DNA code goes about creating spike proteins and that prompts the antibody response,” he said.

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Australia has already missed its COVID-19 vaccination target

Why is it only one dose?

Developing a single-dose COVID-19 vaccine was always a goal, said a spokeswoman for Johnson & Johnson’s pharmaceuticals arm Janssen.

“Given the World Health Organization recommendations for medical interventions in a pandemic setting, which emphasise ease of distribution, administration and compliance — the availability of a safe effective single-dose vaccine to help combat this pandemic, was always considered an important goal.”

And simply put, the Johnson & Johnson COVID-19 vaccine has only one dose because that’s what was tested in phase 1 and 2 clinical trials — and it worked.

Initial results showed a single dose induced a robust immune response and was generally well-tolerated, although we still don’t know how long protection will last.

Based on the vaccine’s success, the company had the confidence to go ahead with a one-dose COVID-19 jab.

Janssen Pharmaceuticals has submitted an application to the TGA for the provisional registration of its COVID-19 vaccine.(

Johnson&Johnson/AP: Cheryl Gerber


However, they are now running an ongoing trial to see if two doses of the vaccine — spaced two months apart — will provide greater, or longer, protection against COVID-19.

This trial will run in parallel to the single-dose trial, allowing researchers to compare protection.

Dr Vally said he was looking forward to seeing further results.

“It stands to reason that if you give the immune system two doses of the vaccine so you’re able to prime the immune system and then boost it, you’re going to improve on those [efficacy] numbers,” he said.

Will we get it in Australia?

Maybe, but it’s too early to know for sure.

The Australian government has agreements with four different coronavirus vaccine suppliers (costing more than $3.3 billion), but none of these arrangements are with Johnson & Johnson.

Janssen Pharmaceuticals (on behalf of its parent company Johnson & Johnson) has already submitted an application to the Therapeutic Goods Administration for the provisional registration of its vaccine.

A TGA spokeswoman confirmed this application was currently being evaluated.

“The TGA has agreed to accept rolling data to enable evaluation as information comes to hand, but will only be in a position to make a registration decision once the required data relating to safety, quality, and efficacy has been provided and assessed,” she said.

Before vaccines are approved for use in Australia, they must undergo thorough vetting by the TGA.

Dr Vally admits other countries don’t have the same luxury of time as Australia does.

In the US, the Johnson & Johnson COVID-19 vaccine has already been authorised for emergency use by the US Food and Drug Administration, which allows the jab to be used while more data is gathered.

Does Australia need the J&J vaccine?

Despite the prospect of a single-dose vaccine, both Dr Vally and Dr Wood encouraged Australians to get the Pfizer or AstraZeneca vaccine when it was offered to them.

“We want to stop people from dying and getting sick and going to hospital with this; Pfizer does that, AstraZeneca does that,” Dr Wood said.

He also said even if — theoretically — the Johnson & Johnson jab was approved tomorrow, it would be logistically challenging to get millions of doses to Australia, a country which would be at the back of the queue.

And Dr Vally said he saw the one-dose Johnson & Johnson being a “huge advantage” for developing countries, where there was huge numbers of people who needed to be vaccinated quickly to stop the spread of coronavirus.