All you need to know about J&J Covid-19 vaccine

All you need to know about Johnson & Johnson's Covid-19 vaccine authorised in US

Both mRNA vaccines showed higher efficacy rates in their trials than J&J's vaccine

Johnson & Johnson's Covid-19 vaccine was granted emergency authorisation in the United States. Credit: AFP Photo

Johnson & Johnson's Covid-19 vaccine was granted emergency authorisation in the United States.

Also read: US authorises J&J's single-dose Covid-19 vaccine, making it third available

The following are details about J&J's shot.

How effective was it in a large study?

Results from a trial of about 44,000 participants show the J&J vaccine was 66% effective in preventing moderate-to-severe Covid-19 globally.

A review of available data by an independent safety monitoring board indicated that a single-dose of the Covid-19 vaccine was generally well-tolerated.

Data in South Africa

In South Africa, where 95% of the cases in the trial were due to infection with the highly contagious B.1.351 coronavirus variant, the vaccine was 64% effective in preventing moderate-to-severe Covid-19 28 days after inoculation.

About 6,000 people in South Africa took part in the trial.

Data in United States

The level of protection from the vaccine against moderate-to-severe Covid-19 infection was 72% in the United States after 28 days.

Data in Latin America

The shot was 66% effective at stopping moderate-to-severe cases in Brazil after 14 days and 68% after 28 days. It was 66% effective in Latin America overall, which involved nearly 18,000 people in Argentina, Brazil, Chile, Colombia, Mexico and Peru.


About 34% of trial participants were over age 60.

17.2% of participants in the trial were Black, 8.3% were American Indian or Alaskan Native, 2.5% were Asian and 45% were Hispanic or Latino.

Side effects

The FDA said the most common reactions were injection site pain at 48.6%, headache at 39%, fatigue at 38.2% and aches and pains at 33.2%. Other side effects included a fever in 9% of participants and a high fever in 0.2% of those who received the vaccine.

How does it differ from the Pfizer and Moderna vaccines?

The Pfizer/BioNTech and Moderna vaccines use new messenger RNA technology to create an immune response and both require two shots. The one-shot J&J vaccine involves a more conventional approach, using a common cold virus to introduce coronavirus proteins into cells to trigger an immune response.

Also read: Johnson & Johnson's single-dose vaccine effective against Covid-19

J&J's vaccine remains stable for at least three months at normal refrigerator temperatures, while the Moderna vaccine must be shipped frozen and the Pfizer/BioNTech option must be shipped and stored at even colder sub-Arctic temperatures.

These factors make it easier to vaccinate larger numbers of people, even in areas with poor transportation and storage infrastructure.

Pfizer/BioNTech and Moderna vaccines were about 94%-95% effective in trials conducted in the United States where variants were not circulating.

How does it rank next to the others?

Both mRNA vaccines showed higher efficacy rates in their trials than J&J's vaccine, but experts cautioned against drawing too much of a distinction between the vaccines because the trials had different endpoints and J&J's was conducted while highly transmissible new variants of the virus were circulating.


Novavax Inc, which is testing its vaccine in South Africa, said it was 60% effective at preventing mild, moderate and severe Covid-19 in patients who did not have HIV. It said about 90% of cases in the study involved the new South African variant. The mid-stage South Africa trial included 4,400 patients.

The vaccine developed by AstraZeneca with Oxford University provided only minimal protection against mild-to-moderate Covid-19 from the South African variant in a relatively small trial. There was no data yet on its effectiveness in preventing severe disease in people who were infected by the variant because the study involved mostly young adults not considered to be at high risk for serious illness.

Supply deals

J&J expects to produce at least a billion doses of its vaccine in 2021 and has signed supply deals for most of that.

The United States agreed to pay over $1 billion for 100 million doses and may purchase an additional 200 million doses.

Other deals include 22 million doses for Mexico, 9 million for Colombia, 30 million the UK, 4 million to South Korea and 400 million for the European Union. It plans to supply 500 million to poorer countries, working with the Covax alliance.

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