Japanese study questions durability of Covid vaccines as antibody protection wanes in many recipients

An analysis of antibody data from 2,526 adults in Fukushima who received two doses and a booster found that nearly half experienced a rapid decline in protective antibodies within nine months of boosting. The study tracked participants from April 2021 through November 2022, with an 18-month follow-up, and focused on the Pfizer-BioNTech and Moderna vaccines.

The researchers identified four patterns of immune response after the booster: durable responders, rapid decliners, vulnerable responders, and intermediate responders. Rapid decliners accounted for about 19% of participants, and vulnerable responders for about 28%; the rest were distributed between durable and intermediate categories. Overall, nearly half of participants fell into the rapid-decline or vulnerable groups.

Infection rates differed modestly between groups: about 5.2% of durable responders were infected, compared with roughly 6% among the rapid decliners and vulnerable responders — a relative increase of about 14%. Within three months of a booster, about one in five in the rapid-decline or vulnerable groups had contracted Covid, rising to roughly one-half by six months, compared with about one in five in the durable group.

However, the authors stressed that the differences in infection risk were not large in absolute terms and called for further work to understand the mechanisms behind weaker or shorter-lived antibody responses. They noted that some individuals did not maintain high antibody levels for an extended period after booster vaccination, which they said left them at higher risk for infection.

The Nagoya University team wrote that additional booster doses or even antibody therapy may be warranted for those predicted to be part of vulnerable or rapid-decliner populations. They cautioned that why some people generate weaker responses remains unclear, and emphasized the need for more research to support fully individualized vaccination strategies. The researchers also reported that people described as having post-viral syndrome (PVS) showed elevated levels of Covid spike proteins, with levels in PVS patients higher than those seen in long Covid cases.

Global context around vaccination efforts provides a broader frame. The World Health Organization has said jabs prevented about 14.4 million deaths in their first year of rollout, with some estimates approaching 20 million. A separate 2022 study led by Imperial College London suggested nearly 20 million lives were saved in the first year after vaccines began rolling out, with the majority of those benefits in high- and upper-middle-income countries.

In total, more than 13.6 billion doses of Covid vaccines have been administered worldwide, and roughly 70% of people have received at least one dose. The vaccines are widely credited with contributing to the easing of lockdowns and other pandemic-era restrictions, even as questions persist about the duration of protection and how best to tailor schedules for individuals.

The study’s findings arrive as researchers discuss a concept some have labeled “post-vaccination syndrome,” a collection of symptoms linked to mRNA vaccines such as brain fog or dizziness. Scientists caution that these findings are preliminary, have not yet undergone peer review, and require additional investigation to determine causal relationships and clinical significance.