mRNA booster provides strong protection against variant COVID-19…Effect persists regardless of age or infection
Variant COVID, a new challenge to vaccine protection
Recent spread of the variants XBB and BA.5 has increased the risk that the protective efficacy of existing vaccines will wane. Even individuals who have received three doses require an additional booster.
mRNA booster shows overwhelming superiority in neutralizing antibodies and ACE2‑RBD binding inhibition
The research team compared immune responses of an mRNA vaccine and an inactivated vaccine using microneutralization assays and ACE2‑RBD binding inhibition analyses. The mRNA booster consistently produced higher neutralizing antibody titers against both the original virus and the variants, and its inhibition effect remained stable.
After breakthrough infection, immunity from mRNA vaccine rises even more
When participants who experienced breakthrough infections were followed, those who had received the mRNA vaccine exhibited a marked surge in neutralizing antibodies that persisted for an extended period. In contrast, the inactivated‑vaccine group showed a modest increase with a shorter duration of maintenance.
Future immune strategy: tailored boosters needed irrespective of age
Analysis by age group revealed that the mRNA booster effect remained pronounced even in individuals aged 60 years and older. Consequently, mRNA‑based personalized boosters are projected to be essential for long‑term COVID‑19 defense, independent of age.
BACKGROUND: The emergence of highly mutated SARS‑CoV‑2 variants challenges vaccine protection. Evaluating long‑term immune protection from boosters is crucial. The experiment compares neutralizing antibody dynamics and ACE2‑RBD binding inhibition induced by mRNA and inactivated vaccine boosters, and assesses the impact of breakthrough infections and age on immune responses. METHODS: This study is based on a previous randomized, double‑blind, parallel controlled trial. Healthy participants aged ≥18 who had received ≥3 inactivated COVID‑19 vaccine doses. Volunteers (32 aged 18‑59 and 32 ≥ 60) were stratified by age and vaccine type (24 mRNA, 8 inactivated in each age group). Pregnant women, those with severe chronic diseases or a history of allergies are excluded. Neutralizing antibodies were measured via microneutralization assay, and ACE2‑RBD binding inhibition by high‑sensitivity electrochemiluminescence. The study assessed changes in antibody levels and ACE2‑RBD binding inhibition pre‑ and post‑infection across age groups to evaluate vaccine efficacy and durability. (Registed number: ChiCTR2200064575). RESULTS: The neutralizing antibody titers from mRNA vaccine showing stronger and more consistent responses against the original strain and variants like XBB and BA.5. After breakthrough infections, mRNA‑vaccinated individuals show a significant and lasting boost in antibodies, while the increase in inactivated vaccine recipients is modest. By age, mRNA‑vaccinated people over 60 experience a faster antibody decline post‑vaccination, whereas the inactivated vaccine group sees an initial rise at three months before declining. For ACE2‑RBD binding inhibition, mRNA vaccines maintain higher early‑phase rates, while inactivated vaccines show a delayed rise at three months followed by decline. CONCLUSIONS: mRNA vaccines induce stronger neutralizing antibodies and broader immunity than inactivated vaccines. Breakthrough infections boost antibody levels more in mRNA recipient
The emergence of variant viruses has made it difficult to achieve sufficient protection with existing vaccines alone. These findings address that gap, enabling us all to continue daily life longer and more safely.