Johnson & Johnson’s experimental COVID-19 experimental vaccine generated a long-lasting immune response in an initial safety study, giving an idea of how it will behave in the real world as the company approaches US regulators for release .
More than 90% of the participants produced immune proteins, called neutralizing antibodies, in 29 days after receiving the injection, according to the report, and the participants formed the antibodies in 57 days. The immune response lasted 71 full days of the trial.
“Looking at the antibodies, there must be good hope and a good reason for the vaccine to work” in the company’s late-stage clinical trials, Johnson & Johnson chief scientific officer Paul Stoffels said in an interview on Tuesday. The company is expected to report the results of these final-stage tests soon.
The one-shot vaccine generates more neutralizing antibodies than a single dose of other COVID-19 vaccines, all of which are two-dose regimens. And when compared to two shots from these rivals, the response to Johnson & Johnson’s single shot is the same range, said Stoffels.
The provisional results of a trial with participants aged 18 and over were published on Wednesday in the New England Journal of Medicine. The data expanded into more limited discoveries that Johnson & Johnson first published in September.
The company’s progress is being closely watched by leading infectious disease experts because its vaccine has the potential to become the first that can protect people after just one injection, making mass vaccination campaigns much easier. The company expects to obtain definitive efficacy data from a final stage study early next month, potentially leading to regulatory authorization in March.
The United States has granted emergency use authorizations for two vaccines, one developed by Pfizer and its German partner, BioNTech, and the other by Moderna. Both employ a technology called messenger RNA that has never been used before in an approved product and each has shown more than 90% effectiveness.
US government officials had previously said that any vaccine over 50% effective would be considered a success. Based on this guidance, Johnson & Johnson aimed for 60% effectiveness, said Stoffels, but “we expected and planned 70%”.
The Johnson & Johnson vaccine candidate is made from a cold virus, called adenovirus, which is modified to make copies of the coronavirus spike protein, which the pathogen uses to enter cells. Although the altered virus cannot replicate in humans, it induces an immune response that prepares the body for actual coronavirus infection.
Within weeks, Johnson & Johnson will learn how their vaccine worked in a final stage test with 45,000 volunteers. Stoffels now thinks it has the potential to be even more than 70% effective, based on early stage findings and other factors.
Another advantage of the Johnson & Johnson injection is that it can be stored at refrigerator temperature for three months.
The study released on Wednesday also found that a second dose of Johnson & Johnson’s injection, given two months later, led to a three-fold increase in neutralizing antibodies. Stoffels considered this to be positive news and said the company is still evaluating how long immunity from a single injection will last and whether higher levels of antibodies will be needed to fight new strains of the coronavirus.