- New evidence suggests that the J&J vaccine is protective against the SARS-CoV-2 mutations circulating worldwide
- The research involved testing the jab against the original variant, as well as four other variants
- The researchers believe that non-neutralising antibodies and T cells may play a protective role against Covid
Johnson & Johnson’s (J&J) single-dose Covid-19 vaccine provides strong protection against the original virus variant first identified in Wuhan, as well as other highly infectious variants, new research published in Nature revealed.
While clinical trial data from the US, Latin America and South Africa have shown that the jab can protect against symptomatic Covid infection, there have been limited data on the immunogenicity (the ability of a vaccine to provoke an immune response) of the jab against variants of concern, the authors wrote.
Their findings are based on tests against the following variants:
- The original virus variant, WA1/2020, first identified in Wuhan, China
- Alpha (B.1.1.7) first identified in the UK
- CAL.20C first detected in southern California
- Gamma (P.1) first identified in Brazil
- Beta (B.1.351), first identified in South Africa
Currently, Beta is dominating cases in South Africa and has been responsible for the large majority of the country's second wave infections.
More than 10 million Americans have already received the vaccine, according to the Centers for Disease Control and Prevention. In South Africa, the jab was administered to more than 290 000 healthcare workers as of April.
The South African government has procured 31 million doses of the vaccine but is currently awaiting the outcome of an investigation by the US Food and Drug Administration (FDA), which is expected to be announced soon. If they give the go-ahead to use the jab, then countries, including SA, will be allowed to continue rolling it out as part of its inoculation programme.
Strong antibody and immune responses
According to the Nature report, authored by 31 researchers, the vaccine-induced antibody and cellular immune responses against these variants in 20 volunteers between the ages of 18 and 55.
"The concern is whether SARS-CoV-2 variants may reduce the efficacy of current vaccines that were designed to protect against the original SARS-CoV-2 strain at the beginning of the pandemic," senior author, Professor Barouch, Director of BIDMC's Center for Virology and Vaccine Research, said in a news release. Barouch is also a Professor of Medicine at Harvard Medical School.
All participants were part of a larger multicentre, randomised, double-blind, placebo-controlled Phase 1/2a study to test the vaccine at various doses and schedules.
Several methods were used to test the antibody and cellular immune responses against the original virus variant and Alpha, Beta, Gamma, and CAL.20C, the authors noted.
What they found
Compared to antibody responses against the original virus variant, there were reductions in neutralising antibodies against the Beta and Gamma variants. Neutralising antibodies fight the SARS-CoV-2 virus’ ability to enter, and therefore infect, human cells.
By comparison, the non-neutralising antibody responses and T cell responses stimulated by the vaccine were “largely preserved”, they said. In other words, they were minimally impacted or not impacted by these variants, the researchers found.
Non-neutralising antibodies cannot prevent viral infection, but previous research related to influenza vaccines has indicated that they may exert a protective function through various immune mechanisms.
T cells are "natural killers", their job is to find infected cells in the human body and destroy them, Professor Thomas Scriba, deputy director of immunology and laboratory director at the South African Tuberculosis Vaccine Initiative, the University of Cape Town, previously explained to Health24.
Non-neutralising antibodies: potentially protective
In an earlier, separate paper published in Nature in February 2021, the authors noted that for most current vaccines, neutralising antibodies are considered as a measurable sign (referred to as a “correlate”) of protection from disease, but that they aren’t necessarily the only mechanism of protection.
Non-neutralising antibodies, they said, may also play a role, although evidence on their role has not been very clear – until now.
In the new study, these non-neutralising antibodies and/or T cell responses may contribute to protection against Covid-19, and further scientists’ understanding of the jab’s protection against variants of concern, the researchers believe.
"Although the mechanistic correlates of protection for Covid-19 are not yet known, the vaccine's robust protective efficacy in these regions raises the possibility that non-neutralising antibodies and/or T cell responses may also contribute to protection," said Barouch.
Alternatively, Barouch added, it is possible that low levels of neutralising antibodies are sufficient for protection against Covid infection.