Different effects of the world’s Covid injection types are revealed in new study that shines light on ‘Adenovirus v mRNA’ debate
The one-shot adenovirus J&J Covid-19 vaccine provides stable but low-level immunity that stays for months, a new study has found, while mRNA jabs’ initially higher number of antibodies “declines sharply” over the same period.
An immune response induced by Johnson & Johnson’s Janssen adenovirus vaccine appears to show “minimal-to-no evidence of decline” over eight months, the fresh study in the US reports, detailing the dynamics of the antibody response in the “follow-up period” after immunizations with each of the three American vaccines.
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Apparently, Pfizer and Moderna cannot boast a similar durability in their mRNA vaccines’ efficacy, the study shows. Antibody titer levels (a term of measurement) elicited by both of them tend to decline “sharply by six months after vaccination” and fall even further by eight months, according to the data collected by the specialists from the Beth Israel Deaconess Medical Center in Boston, Massachusetts, and the University of North Carolina at Chapel Hill.
The two mRNA vaccines apparently still greatly outperform the one-shot Johnson & Johnson jab during the “peak immunity” period, between two and four weeks after full immunization, the study admits. In the long run, however, they quickly lose their sizeable lead in efficacy and eventually land at the same antibody response level as that of the Johnson & Johnson jab based on the adenovirus vector principle – the same as the ones used by the UK’s AstraZeneca and by Russia’s Sputnik V.
The study also demonstrated that the Johnson & Johnson jab supposedly even somewhat outperforms both mRNA vaccines when it comes to antibody responses eight months after full immunization. Its live-virus neutralizing antibody response and a certain type of T-cell response appeared to be higher than those of Pfizer and Moderna jabs at that time.
‘Statistical discrepancy’ or potential breakthrough?
Whether it is indeed better in the long run is difficult to ascertain, though, since the data obtained from just over 60 participants, including only eight immunized with a Johnson & Johnson jab, appear to be somewhat “lacking,” Maxim Skulachev, a leading research associate at the Belozersky Institute at Moscow State University (MSU), believes.
“There are not enough statistics,” he told RT, when asked to comment on the study results. In fact, Janssen jab’s better performance could be a matter of “statistical discrepancy,” he added. He also pointed to the fact that the study did not include the new data on Johnson & Johnson booster shot.
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The study came just about a week after Russia published results of a study that its own one-shot adenoviral vector vaccine – Sputnik Light – offers at least 70% protection against the Covid-19 Delta variant for at least three months after vaccination. Moreover, the director of the Gamaleya National Research Center of Epidemiology and Microbiology, which developed Russia’s leading vaccine, Alexander Gintsburg, claimed that getting a booster shot of Sputnik Light, after initial vaccination with Sputnik V, prolongs immunity by six to seven months.
“Additional boosting with the second component of Sputnik V raises the level of protective antibodies and is quite significant. And in the range from 300 to 500 bounding antibody units (BAU), boosting only with Sputnik Light is enough. And, accordingly, this is the most common range after six months of using Sputnik V, so the use of Sputnik Light after six months for such a category of vaccinated people is a very promising and effective way to extend protective immunity for at least another six to seven months,” he said, citing data from more than 4,000 vaccinated Moscow residents.
The Russian jab could potentially also be successfully used as a “booster shot” to re-vaccinate people who’ve earlier been immunized with other vaccines. A small-scale study in Azerbaijan this year showed in particular a fourfold increase in antibodies to the spike protein of the virus in 85% of participants in a Sputnik Light clinical trial, who’d previously been immunized with AstraZeneca’s jab.
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Skulachev also believes that Sputnik Light might yet turn out to be a viable re-vaccination solution. The study of three American vaccines showed that all of them show similar efficacy in the long run, he said. Since one of these is an adenoviral vector one, “we can assume it will work with Sputnik as well.”
In September, the Johnson & Johnson pharmaceutical company said that administering the booster dose some two months after the first dose made antibody levels four to six times higher and raised the vaccine’s efficacy to 94% against moderate and severe Covid-19 cases – up from just 66% provided by the first dose.
Last week, the US Food and Drug Administration (FDA) endorsed J&J’s booster proposal, even though it did not set a fixed timeline for administering the second shot.
Still, even in the present state, the study results might be good news for adenoviral vector vaccines worldwide, Skulachev said. Although the antibody response level provided by the one-shot Johnson & Johnson jab is “more than 10 times lower” than that of the mRNA vaccines during the “peak immunity period,” its durability does it credit, he believes.
“It is clear that it is definitely not worse in the long run,” Skulachev said, adding that the “greatest result” demonstrated by the study is that all the vaccines provide some “baseline” immunity even eight months after vaccination.
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“Over time, immunity responses induced by all vaccines come to a certain ‘steady state,’ which protects from hospitalization and death,” Skulachev explains, adding, however, that it might not be enough to protect a person from contracting the virus.
“We have this baseline immunity induced by all vaccines. This is something that protects [a person] against hospitalization,” he added, calling such data “reassuring.” This ‘baseline’ immunity could also be a good basis for re-vaccination booster shots, the scientist believes.
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