J&J's one-dose vaccine 85% effective against severe COVID, study suggests

Alexandra Thompson
·7-min read
A doctor is giving a flu vaccine for illness prevention.
The UK has approved three coronavirus vaccines. (Stock, Getty Images)

A single shot of Johnson & Johnson’s (J&J) coronavirus vaccine is 85% effective at warding off severe disease, the company has announced.

The UK has approved coronavirus jabs developed by Pfizer-BioNTech, AstzraZeneca-University of Oxford and Moderna; all of which have a two-dose regimen.

In J&J’s ongoing phase 3 trial, the last stage before seeking regulatory approval, scientists tested a single shot of its vaccine candidate on more than 43,700 volunteers, of whom over a third were older than 60.

The pharmaceutical giant has presented results showing the jab was 85% effective at preventing severe disease “across all regions studied”, some of which had new variants of the coronavirus circulating, after 28 days.

No deaths or coronavirus-related hospitalisations occurred 28 days after the participants were vaccinated, “demonstrating complete protection”, according to J&J.

When it came to warding off “moderate to severe” illness, the vaccine was 66% effective overall.

Read more: Germany recommends over 65s bypass AstraZeneca coronavirus jab

J&J is testing a two-dose regimen of the jab in the UK, with the scientists behind the trial acknowledging “two doses is better than one”.

Amid a “raging pandemic”, however, it is important to understand a vaccine’s efficacy after just one shot, they added. The trials that led to the approved coronavirus vaccines being signed off in the UK were not designed to assess efficacy after one dose.

The J&J team hopes to start the process towards vaccine approval in early February. The UK has pre-ordered 30 million doses of the jab, which are expected to be available later in 2021 if it gets the green light.

Young woman wearing surgical mask in front of home
Vaccines have long been hailed as a route back to life as we once knew it, potentially freeing people from the constraints of face coverings. (Posed by a model, Getty Images)

“These top-line results with a single-shot COVID-19 [the disease caused by the coronavirus] vaccine candidate represent a promising moment,” said Dr Paul Stoffels, J&J’s chief scientific officer.

“The potential to significantly reduce the burden of severe disease, by providing an effective and well-tolerated vaccine with just one immunisation, is a critical component of the global public health response.

Read more: Just 21 anaphylaxis cases to first Pfizer coronavirus jab

“A one-shot vaccine is considered by the World Health Organization to be the best option in pandemic settings; enhancing access, distribution and compliance.

“Eighty five per cent efficacy in preventing severe COVID-19 disease and prevention of COVID-19-related medical interventions will potentially protect hundreds of millions of people from serious and fatal outcomes of COVID-19.

“It also offers the hope of helping ease the huge burden placed on healthcare systems and communities.”

The preliminary results will be submitted to a peer-reviewed journal “in the coming weeks”.

Watch: Can you catch coronavirus twice?

The study is being carried out in eight countries across three continents, testing the vaccine candidate against emerging strains in the US, Latin America and South Africa.

Concerns have been raised mutations on key regions of the coronavirus may mean new variants, like those that arose in the UK and South Africa, could be immune to long-awaited vaccines.

“Protection was generally consistent across race, age groups, including adults over 60 years of age, and across all variants and regions studied,” according to J&J.

Nearly all (95%) of the coronavirus cases identified in the South African subset of the trial were its newly-emerged variant, added the company.

Read more: Coronavirus vaccines are safe and any side effects mild

Of the more than 43,700 participants, 34% were over 60.

Older people generally have a more subdued immune response to infections and vaccines than their younger counterparts.

Germany’s vaccine committee has recommended people over 65 should not receive the AstraZeneca-Oxford jab due to a lack of efficacy data in this age group.

This has largely been dismissed by other scientists, with Boris Johnson also saying he is unconcerned about the vaccine’s effectiveness in older adults.

The J&J results show 468 symptomatic coronavirus cases have arisen in the ongoing trial to date.

Overall, the vaccine is said to be 66% effective at preventing moderate to severe COVID-19 28 days after immunisation, with the onset of protection observed as early as day 14.

Severe disease is being defined as a confirmed coronavirus infection, along with “signs consistent with severe systemic illness”, intensive care admission, respiratory failure, shock, organ failure or death, “among other factors”.

Moderate illness is diagnosed when a participant has a confirmed infection, as well as evidence of pneumonia, deep vein thrombosis, shortness of breath or abnormal blood oxygen saturation, an unusual respiratory rate, or “two or more systemic symptoms suggestive of COVID-19”.

In the US specifically, the jab was found to be 72% effective at warding off moderate to severe illness at day 28, compared to 66% in Latin America and 57% in South Africa.

The differences in the efficacy results have been put down to the variants circulating in the distinct regions. The comes shortly after the vaccine development firm Novavax announced its coronavirus jab candidate was 89% effective overall in the UK, but just 60% in South Africa.

When it comes to severe disease only, J&J’s vaccine had an overall efficacy rate of 85% across all the regions after 28 days, the results show.

The jab is also said to have a “clear effect” on the need for “medical interventions”, with none of the participants who had the vaccine being admitted to hospital or intensive care, or requiring ventilation, at the 28-day mark.

“Efficacy against severe disease increased over time, with no cases in vaccinated participants reported after day 49,” wrote J&J.

Read more: Pfizer jab shows signs of efficacy against new coronavirus variants

When it comes to safety, “an independent group of experts did not report any significant safety concerns relating to the vaccine”, with it generally being “well-tolerated”.

Alex Gorsky, J&J’s CEO, added: “Johnson & Johnson embarked on the global effort to combat the COVID-19 pandemic a year ago, and has brought the full force of our capabilities, as well as tremendous public-private partnerships, to enable the development of a single-shot vaccine.

“Our goal all along has been to create a simple, effective solution for the largest number of people possible, and to have maximum impact to help end the pandemic.

“We’re proud to have reached this critical milestone and our commitment to address this global health crisis continues with urgency for everyone, everywhere.”

Like the AstraZeneca-Oxford vaccine, J&J’s candidate does not require the ultra-cold temperatures of the Pfizer-BioNTech and Moderna jabs, and can instead be stored in a standard fridge.

If approved, the “single-dose vaccine candidate is estimated to remain stable for two years at -20C (-4F), at least three months of which can be at temperatures of 2-8C (36F–46F)”.

Speaking of J&J’s results, Professor Kevin Marsh from the University of Oxford, said: “It is possible some people will look at the overall reported efficacy of 66% in preventing moderate to severe COVID-19 and focus on comparisons with potentially higher ‘top line’ efficacy reported for some other vaccines.

“This would be a mistake.

“The real headline result is a single-shot vaccine, capable of easy long-term storage and administration, provided complete protection against hospitalisation and death.

“This is important because the immediate requirement of vaccination globally is to limit deaths as quickly as possible.

“While potentially important for all regions, these results are especially encouraging for Africa and LMIC’s [low to middle income countries] globally where the combination of single-shot, ease of storage and protection against multiple variants is critical.”

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