The drugmaker’s latest findings are based on two Phase 2 studies conducted on people previously inoculated with its single-shot vaccine. Participants in the studies got a booster dose six to eight months after their initial shot of J&J’s COVID-19 vaccine.
According to interim data released in a company statement on Aug. 25, the J&J booster vaccine generates a “rapid and robust” increase in spike-binding antibodies that are “nine-fold higher” than those seen four weeks after the primary dose.
The drugmaker noted that an increase in binding antibody responses was found in participants aged between 18 and 55, as well as in those 65 years and older who had received a lower booster dose.
Unlike neutralizing antibodies, which destroy the CCP (Chinese Communist Party) virus, binding antibodies attach to the virus but do not destroy it or prevent infection. Instead, they alert the immune system of its presence so white blood cells can be sent to destroy it.
A prior study released in July found that neutralizing antibody responses in those vaccinated by the drugmaker’s single-shot vaccine were durable until at least eight months with a single dose.
“We have established that a single shot of our COVID-19 vaccine generates strong and robust immune responses that are durable and persistent through eight months,” said Dr. Mathai Mammen, J&J’s global head of research and development. “With these new data, we also see that a booster dose of the Johnson & Johnson COVID-19 vaccine further increases antibody responses among study participants who had previously received our vaccine.”
“We look forward to discussing with public health officials a potential strategy for our Johnson & Johnson COVID-19 vaccine, boosting eight months or longer after the primary single-dose vaccination,” he added.
Vaccine makers, including Pfizer and Moderna, have said evidence of waning antibody levels in fully vaccinated people after six months, along with an increasing rate of breakthrough infections in regions affected by the Delta variant, supported the need for boosters.
J&J said the company is working with the U.S. Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA), the European Medicines Agency, the World Health Organization, and other health authorities on delivering a booster shot with the J&J vaccine.
Earlier this year, the CDC and FDA recommended halting usage of the J&J vaccine after reports of blood clots emerged among some individuals who had received it. Weeks later, the two agencies said that the vaccine could again be used, but with an FDA warning.
“This pause was essential to our ability to inform the public, inform physicians, and acquire more data for presentation and for analysis,” Dr. José Romero, chairman of the CDC’s Committee of Immunizations, said in April. The vote was 10–4 in favor of recommending the vaccine to adults who are 18 or older. There was one abstention.
Because of its one-dose convenience and less onerous storage and shipping requirements, J&J’s shot was previously touted as an important tool for vaccinations in hard-to-reach areas. But after the safety concerns and manufacturing stumbles, it has the lowest uptake in Europe among all the vaccines approved for use, and has also struggled to gain traction in the United States.
U.S. Surgeon General Dr. Vivek Murthy said on Aug. 22 that those who have received the J&J single-dose vaccine will likely need booster shots, after other federal health officials and he said last week that those who got the Pfizer and Moderna vaccines would be recommended to get a third shot starting in September.
The J&J vaccine uses a more traditional adenovirus mechanism, whereas the Pfizer and Moderna vaccines use mRNA technology.
Reuters and Jack Phillips contributed to this report.