J&J COVID-19 booster shot produces robust antibody response

By Angela Betsaida B. Laguipo, BSNAug 31 2021

The coronavirus disease (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread across the globe. The total number of confirmed infections currently standing at over 217.29 million.

Study: Johnson & Johnson Announces Data to Support Boosting its Single-Shot COVID-19 Vaccine. Image Credit: Wachiwit/ Shutterstock

Amid a huge drive worldwide to immunize the global population, the emergence of novel SARS-CoV-2 variants threatens vaccine efficacy. Johnson & Johnson announced data supporting the use of the Ad26.COV2.S vaccine (Johnson & Johnson–Janssen) as a booster shot for people previously vaccinated with the single-dose vaccine.

The study findings supported the interim Phase ½a data published in the New England Journal of Medicine. The study showed neutralizing antibody responses produced by the Johnson & Johnson–Janssen vaccine was robust and stable eight months after immunization.

Trial background

The Johnson & Johnson single-shot COVID-19 vaccine induced strong and stable humoral and cellular immune responses.

The Phase 1/2a trial is an ongoing multi-center, randomized, double-blind, and placebo-controlled trial to determine if the J&J vaccine is safe to use and can induce an immune response at two dose levels. The vaccine is administered intramuscularly in the trial as a single-dose or two-dose schedule about eight weeks apart in healthy adults.

Overall, the trial results were obtained from 25 enrolled adults between 18 and 55 years of age at a single site at Beth Israel Deaconess Medical Center while additional follow-up with the participants is underway. The team administered the vaccine to 20 study participants, and five received a placebo.

To date, the trial has been performed in clinical sites in Belgium and the United States.

Among those who received the vaccine, all developed antibody responses on the 239^th day. However, the median binding antibody titer against the parental WA1/2020 strain receptor-binding domain (RBD) was 645 on day 29, 1,772 on the 57^th day, 1,062 on the 71^st day, and 1,306 on day 239. Meanwhile, the median WA1/2020 pseudovirus neutralizing antibody titer was 272 on day 29, 169 on day 57, 340 on day 71, and 192 on day 239.

Single-dose vaccine efficacy

In the report, the findings indicate that a single dose of the vaccine induced dual protection mechanisms against COVID-19, including against the Delta variant and other variants of concern that lasted for about eight months. Variant-specific neutralizing antibodies were present over the eight-month period, which inferred the maturation of B-cell responses. Notably, T-cell responses were especially robust over time.

In anticipation of the potential need for boosters, the researchers performed two Phase 1/2a studies in people previously vaccinated with the single-shot vaccine. The study results demonstrated that the booster shot elicited a rapid and robust increase in spike-binding antibodies in the 17 study participants, nine-fold higher than 28 days after the first dose. The booster shot was administered six months after the first one. Notably, people between 18 and 55 and 65 and above exhibited significant increases in binding antibody responses.

The pharmaceutical company said it plans to submit the study results to the Food and Drug Administration (FDA) to help hasten approval use of a booster shot.  The company emphasized that the study supports a strategy to give a booster at eight months.

Further, the company is in talks with other agencies to approve the Johnson & Johnson-Janssen booster shot, including the U.S. Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), the European Medicines Agency, and other hea5lth authorities.

On August 18, health officials in the United States recommend a booster shot eight months after receiving the second dose of Pfizer or Moderna vaccine. A Johnson & Johnson vaccine will also be needed, particularly for those who had the vaccine first and are eligible for a booster, such as the most vulnerable people.

However, a booster plan still requires the assessment and approval of the FDA, which will review the efficacy and safety of a second dose of the J&J vaccine.