Single-Shot Vaccine Effective Against Variants

In an NIAID-funded study, the immune response to the single-shot Janssen/Johnson & Johnson Covid-19 vaccine remained robust against variants. The results appeared in Nature.

The three vaccines against SARS-CoV-2—the virus that causes Covid-19—that have received emergency authorization for use in the U.S. were developed early in the pandemic, before the virus mutated to produce the variants now found around the world. 

In the current study, researchers examined the immune response to SARS-CoV-2 variants after vaccination with the Ad26.COV2.S vaccine, developed by Janssen/Johnson & Johnson. The researchers tested antibody and immune cell activity against the original strain of SARS-CoV-2 as well as the alpha, beta and gamma variants and another variant first isolated in California.

Among those who received Ad26.COV2.S, the team found neutralizing antibodies against the variants. But the vaccine induced lower levels of neutralizing antibodies against the variants compared with the original virus. For example, the team saw a 3-fold reduction in antibodies that could recognize and bind to the gamma variant. They found a 5-fold reduction in those targeting the beta variant.

Yet other immune responses against the variants resembled those against the original virus. These included the production of non-neutralizing antibodies, which can help immune cells recognize an invading pathogen. Different types of T cells, which help recognize and kill pathogens, also responded similarly against the variants compared with the original virus.

The different types of immune responses to the vaccine may account for the protection against variants seen in South Africa and Brazil during earlier studies, when the beta and gamma variants dominated. Newer variants, such as the rapidly spreading delta variant, will also need to be tested.—adapted from NIH Research Matters