Here's what you need to know about Johnson & Johnson's COVID-19 vaccine

WHAT YOU NEED TO KNOW

Johnson & Johnson announced the launch of its large-scale study (Phase 3 trial) to test a two-dose regimen of its experimental COVID-19 vaccine among thousands of volunteers.
The U.S. drugmaker plans to enrol up to 30,000 participants globally for the study.
The UK arm of the study is aiming to recruit 6,000 participants of the total 30,000 target.
This study runs in parallel with Johnson & Johnson’s single-dose regimen trial launched in September, involving 60,000 participants.

WHAT’S THE DIFFERENCE BETWEEN ONE-DOSE & TWO-DOSE REGIMEN?

When a COVID-19 vaccine comes to the market, people will likely need two doses. The second dose will allow the body better recognise proteins created by the COVID-19 virus.
The second dose will increase immunity. However, how long that immunity lasts remains to be seen.
It’s not uncommon to administer two-dose vaccines. Many other vaccines such as ones to protect against measles or rubella require back-to-back doses to be most effective.
Last week, Pfizer and BioNTech said interim results from its COVID-19 vaccine trials showed 90 percent effectiveness. This vaccine requires a two-dose regimen to achieve that high effectiveness. The two shots are administered 21 days apart.
In Johnson & Johnson’s two-dose regimen study, participants will be given a first dose of either a placebo or the experimental shot, currently called Ad26COV2, followed by a second dose or placebo 57 days later.
The company said the two-dose trial follows positive interim results from the company's study that showed a single dose of its vaccine candidate induced a robust immune response.

HOW IS JOHNSON & JOHNSON’S VACCINE DIFFERENT FROM PFIZER’S?

Pfizer-BioNtech vaccine uses a new form of biotechnology known as messenger RNA or mRNa.
How does it work? mRNA vaccines train the body’s immune system to recognize a threat like a virus. The body then produces antibodies to protect itself against the virus.
Meanwhile, Johnson & Johnson’s candidate vaccine uses a common cold virus known as adenovirus type 26, or Ad26, to deliver coronavirus proteins into cells in the body, prompting the body to mount an immune defense against the virus.
The vaccine uses the same technology used for Johnson & Johnson's Ebola, Zika and HIV vaccines.
Vaccine researcher at Beth Israel Deaconness Dr. Dan Barouch, who led the research in collaboration with Johnson & Johnson said this: “This study shows that even just a single immunization with the Ad26 vaccine leads to neutralizing antibody responses and robust protection of monkeys against COVID-19.”

THE POTENTIAL AND CHALLENGES

Distributions of vaccines come with supply-chain challenges
One potential advantage for Johnson & Johnson’s is that its vaccine candidate does not need to be kept as cold as some other vaccines, which is important for distribution to developing countries.
Pzifer and BioNTech candidate vaccine needs to be kept at - 70 degrees Celsius or below.
Johnson & Johnson said its vaccine is expected to be stable at refrigerated temperatures of -20 degrees Celsius and at least three months at 2-8 degrees Celsius.
The flu vaccine must be kept at 2-8 degrees Celsius, either inside a refrigerator or inside a properly chilled insulated cooler.