Coronavirus: Vaccines/Immunity

J&J vaccine offers long-lasting immune response in early study

Progress of one-shot vaccine closely watched, for it offers ease of distribution, mass inoculation

Items for Johnson & Johnson's one-shot vaccine trial seen at a medical facility in Santiago, Chile. A study released on Wednesday found that a second dose, given two months later, led to a three-fold rise in antibodies.
Items for Johnson & Johnson's one-shot vaccine trial seen at a medical facility in Santiago, Chile. A study released on Wednesday found that a second dose, given two months later, led to a three-fold rise in antibodies. PHOTO: REUTERS

NEW YORK • Johnson & Johnson's experimental one-shot Covid-19 vaccine generated a long-lasting immune response in an early safety study, providing a glimpse at how it will perform in the real world as the company inches closer to approaching United States regulators for clearance.

More than 90 per cent of participants made immune proteins, called neutralising antibodies, within 29 days after receiving the shot, according to the report, and all participants formed the antibodies within 57 days.

The immune response lasted for the full 71 days of the trial.

"Looking at the antibodies, there should be good hope and good reason that the vaccine will work" in the company's late-stage clinical trial that is soon to report results, J&J chief scientific officer Paul Stoffels said on Tuesday.

The one-shot vaccine generates more neutralising antibodies than a single dose of other frontrunner Covid-19 vaccines, all of which are two-shot regimens.

But when compared with two shots of these rivals, the response to J&J's single shot is in the same range, Mr Stoffels noted.

Interim results from the phase 1/2 trial of 805 participants aged 18 and older were published on Wednesday in the New England Journal of Medicine. The data expanded on more limited findings J&J first published in September.

J&J's progress is being closely watched by top infectious disease experts because its vaccine has the potential to become the first that can protect people after just one shot, making mass-vaccination campaigns much easier.

The company expects to get definitive efficacy data from a final-stage study by early next month, potentially leading to regulatory authorisation by March.

The US has granted emergency-use authorisations to two vaccines, one developed by Pfizer and its partner BioNTech, and the other by Moderna. Both employ a technology called messenger RNA that has never before been used in an approved product, and each showed more than 90 per cent efficacy against Covid-19 symptoms.

Those results were better than expected. US government officials had earlier said any vaccine with greater than 50 per cent efficacy would be considered a success.

Based on that guidance, J&J aimed for 60 per cent effectiveness but "we hoped and planned for 70 per cent", Mr Stoffels said.

Within weeks, J&J will learn how its vaccine performed in a late-stage trial of 45,000 volunteers.

Mr Stoffels now thinks it has the potential to be even higher than 70 per cent effective, based on the early-stage findings and other factors.

Dr Moncef Slaoui, chief scientific adviser to the US' Operation Warp Speed vaccine development and distribution effort, said on Wednesday that he anticipates J&J's one-shot vaccine will show 80 to 85 per cent effectiveness.

J&J and its government partners cannot see the data for the time being, a standard measure to prevent bias. Experts have said that a single-shot vaccine offers ease of distribution and administration.

Vaccines from Moderna, AstraZeneca and the Pfizer-BioNTech partnership all require two shots, which means repeat shipping and clinic visits.

While Moderna and Pfizer-BioNTech's shots must be frozen, J&J's shot can be stored at refrigerator temperatures for three months.

"A single dose is going to be so much more effective in the world," Mr Stoffels said. "We are very confident that it works" but another trial J&J is conducting of its vaccine plus a booster shot "will give us a backup".

The study released on Wednesday also found that a second dose of J&J's shot, administered two months later, led to a three-fold increase in neutralising antibodies.

Mr Stoffels said that is positive news, as the drugmaker is still evaluating how long immunity from the single shot will last, and whether higher antibody levels will be needed to combat new strains of the virus.

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A version of this article appeared in the print edition of The Straits Times on January 15, 2021, with the headline J&J vaccine offers long-lasting immune response in early study. Subscribe