A common antibiotic switches self-amplifying RNA vaccines on and off — with 10x range between states

Key Findings

💉 The 2025–2026 COVID vaccines are working in older adults — with a meaningful gap between the two

• Among 233,072 adults aged 65+ who received mRNA-1283 (Moderna's updated formula), protection against COVID-related hospitalization was 59.3% — rising to 66.9% in those 75 and older.
• For 422,610 BNT162b2 (Pfizer) recipients in the same age group, hospitalization protection was 48.3%, and 45.9% in those 75+.
• Both vaccines also reduced medically attended COVID (doctor visits, urgent care) by roughly 41–50% across age groups.
• This is a retrospective real-world study using matched cohorts with inverse probability weighting to balance differences between groups — not a randomized trial.

🔬 A new NMR method maps what's actually inside an mRNA vaccine particle — and the structure may surprise you

• Using a technique called dynamic nuclear polarization (DNP)-enhanced solid-state NMR, researchers directly detected encapsulated mRNA inside intact lipid nanoparticles (LNPs) — the tiny fat bubbles used to deliver mRNA vaccines.
• The data support a concentric, layered architecture: PEG-lipids (the slippery outer coating) sit at the surface, helper lipids (like DOPE and cholesterol) form intermediate layers, and the mRNA sits at the core.
• This "core-shell" model was confirmed by numerical simulations testing eight different structural arrangements — the layered model best fit all the experimental data.
• The internal structure of LNPs carrying large mRNA has been poorly understood; this approach offers a way to directly probe it without breaking the particles apart.

🎯 LNPs delivered antibodies directly into cells — and protected mice from Parkinson's-linked proteins

• Antibodies are normally too large and charged to enter cells on their own — they work on the outside. This study used LNPs to deliver full-length antibodies directly into the cytoplasm (the cell's interior).
• The platform worked across multiple cancer cell lines, inhibiting key proteins involved in inflammatory and cancer signaling pathways that are normally unreachable by standard antibody drugs.
• In mice, LNPs carrying α-synuclein-specific antibodies (targeting a protein linked to Parkinson's disease) were delivered systemically using organ-targeted LNP formulations — as was a RelA-targeting antibody for acute lung injury.
• The approach was tested with several different therapeutic antibodies, suggesting it may generalize across targets.

⚠️ Anti-PEG immune responses can block mRNA vaccines — and changing the formula doesn't fix it

• PEG (polyethylene glycol) is a coating on virtually all approved LNP-based medicines, including COVID vaccines. A single LNP dose can trigger the immune system to make anti-PEG antibodies that neutralize future doses.
• Researchers tested whether changing the PEG-lipid chemistry, PEG concentration, mRNA cargo, or injection route on the second dose could prevent this efficacy loss — none of these adjustments worked.
• LNPs that triggered anti-PEG antibodies also impaired delivery of the FDA-approved MC3 LNP formulation (used in the drug Onpattro), suggesting the problem crosses product lines.
• Lowering PEG concentration reduced immune reactions but also reduced potency — a direct tradeoff with no clear winner.
• This is a preprint and has not yet been peer-reviewed.

🦴 In mice, bone-targeted LNPs carrying anti-sclerostin mRNA restored trabecular bone in an osteoporosis model

• Standard LNPs overwhelmingly accumulate in the liver — a major barrier for treating bone diseases. Researchers attached an Asp8 peptide (a short protein chain that binds to hydroxyapatite, the mineral in bone) to LNP surfaces to redirect them.
• In mice with surgically induced osteoporosis (ovariectomy model), the bone-targeted LNPs (SA@LNP-D) reduced liver accumulation and specifically accumulated in bone tissue.
• The LNPs carried mRNA encoding an anti-sclerostin antibody — sclerostin is a protein that normally suppresses bone formation. Blocking it both stimulated new bone formation and inhibited bone breakdown.
• Bone-targeted LNPs showed stronger therapeutic effects on trabecular bone mass and microstructure than conventional (untargeted) LNPs in the same model.

📊 After repeated COVID vaccination, IgG4 antibodies rise — and may be linked to more breakthrough infections

• In a cohort of healthcare workers in Spain, repeated mRNA vaccination was associated with a progressive shift toward IgG4 (a specific antibody subtype) — a pattern that was less pronounced when infection came before vaccination.
• IgG4 showed broader reactivity to Omicron variants than IgG1 (the more typical antibody subtype), and both IgG2 and IgG4 decayed more slowly in the blood than IgG1.
• During the Omicron wave, elevated IgG2 and IgG4 were linked to increased risk of breakthrough infection, while higher IgG1 and antibodies that activate immune complement were associated with protection.
• IgG4 levels correlated with complement-activating antibodies only in people with lower IgG1 — suggesting the two subtypes may compete.