Johnson & Johnson announced on Tuesday that a second dose of its Covid-19 vaccine enhanced the effectiveness of its first shot to 94 per cent against moderate to severe forms of the disease in the United States if it is administered approximately two months after its first shot.

In comparison, its single dose provided a 70 per cent protection.

J&J will use the data to present its case to US regulators to get a booster shot, even though the company insists on the safety of its vaccine as a tool for alleviating the global pandemic.

President Joe Biden is calling for booster shots to combat the rising number of hospitalizations due to the Delta variant. J&J, which has the only single-shot Covid-19 vaccine that has been approved in the United States and is under pressure to provide evidence of the effectiveness of an extra dose.

Dr. Paul Stoffels, J&J’s chief scientist officer, stated that the company now has “evidence that a booster shot further enhances protection against Covid-19”.

J&J stated that a booster administered two months after the initial dose raised antibody levels by four to six-fold. Data released last month showed that antibody levels rose twelvefold six months after the initial dose. This suggests that there was a significant improvement in protection due to the longer interval between doses.

Side effects from two doses were similar to those observed in studies using a single-dose vaccine. Although the data are still being peer reviewed, they will be published in the coming months.

Only Pfizer Inc, and BioNTech SE have provided enough data to allow U.S regulators to determine whether boosters are necessary before the Sept. 20 deadline set by the Biden Administration for distributing booster shots. This week, a decision is expected on the vaccine.

A FDA advisory committee voted Friday to authorize emergency Pfizer shots to Americans 65 years and older, and for those at high risk of serious illness. However, they voted against wider approval and wanted to see more data.

J&J stated that it submitted data to FDA and plans on submitting it to other regulators and the World Health Organization to help inform their decision-making.

The Phase III trial, which involved up to 30,000 participants, tested the efficacy of a second dose 56 days after the first. It was conducted in adults aged 18 and over.

The study showed that the J&J vaccine is 94per cent effective in the prevention of moderate to severe diseases in the United States. However, the results were not conclusive. There was only one case of mild to severe disease in the vaccine group and 14 cases in the placebo group. This creates a large confidence interval, raising doubts about the validity of the result.

The company stated that the study was short and only lasted for 36 days. However, it found that a second dose was well-tolerated.

On Tuesday, the company stated that a separate study of almost 400,000 Americans who received the J&J shot revealed that the vaccine was 79per cent effective in preventing Covid-19  infection and 81per cent effective in preventing hospitalizations. This compares with 1.52,000,000 people who were not vaccinated.

J&J stated that there was no evidence of decreased effectiveness during the study’s period from March to late June – which included the Delta variant’s impact.

(Adapted from WebMD.com)