Johnson & Johnson says Covid-19 booster shot is 94% effective

Johnson & Johnson said on Tuesday a second shot of its Covid-19 vaccine given about two months after the first increased its effectiveness to 94 per cent in the United States against moderate to severe forms of the disease. That compares to 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 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 caused by the Delta variant and J&J, the only drugmaker with a single-shot Covid-19 vaccine approved in the United States, 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 four to six-fold. When given six months after the first dose, antibody levels shot up twelve-fold, data released last month showed, suggesting a large improvement in protection with the longer interval between doses. 

Side effects with two doses were comparable to 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 SE have submitted sufficient data for U.S. regulators to evaluate whether boosters are warranted ahead of the Biden Administration's September 20 deadline for rolling out booster shots. A decision on that vaccine is expected this week.

On Friday, an FDA advisory committee voted to recommend emergency authorisation of additional Pfizer shots for Americans 65 and older and those at high risk of severe illness, but voted to recommend against broader approval, saying they want to see more data.

J&J said it has submitted data to the FDA and plans to submit it to other regulators, the World Health Organization and other vaccine advisory groups worldwide 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.