Johnson & Johnson says booster shot increases protection dramatically

It says booster given 2 months after first dose increases antibody levels fourfold

CHICAGO : Johnson & Johnson (J&J) said yesterday a second shot of its Covid-19 vaccine given two months after the first increased its effectiveness to 94 per cent against moderate to severe forms of the disease.

That compares with 70 per cent protection with a single dose. The data will help J&J make its case to US regulators for a booster shot even as the American company stresses the durability of its single-shot vaccine as a tool to ease the global pandemic.

US President Joe Biden is pushing for booster shots in the face of surging hospitalisations, and J&J, the only drugmaker with a single-shot vaccine approved in the US, has been under pressure to produce evidence on the effectiveness of an additional dose.

The company has now "generated evidence that a booster shot further increases protection against Covid-19", Dr Paul Stoffels, J&J's chief scientific officer, said in a statement.

J&J said a booster given two months after the first dose increased antibody levels fourfold to sixfold. When given six months after the first dose, antibody levels shot up twelvefold, data released last month showed, suggesting a large improvement in protection with the longer interval between doses. Side effects with two doses were comparable with those seen in studies with the single-dose vaccine. The data is yet to be peer reviewed but will be submitted for publication in the coming months.

To date, only Pfizer-BioNTech have submitted sufficient data for US regulators to evaluate whether boosters are warranted ahead of the Biden administration's Sept 20 deadline for rolling out booster shots.

A decision on that vaccine is expected this week.

J&J said it has submitted data to the US Food and Drug Administration and plans to submit it to other regulators, the World Health Organisation and other vaccine advisory groups to inform their decision-making.

The phase III two-dose trial of up to 30,000 participants tested the effectiveness of a second dose given 56 days after the first in adults 18 and older.

J&J said there was no evidence of reduced effectiveness over the study's duration from March to late July - a period that included the impact of the Delta variant. - REUTERS