Question explored with the scientific record
Conversation so far
- 1 Is the mRNA flu jab safe
- 2 Have any mRNA flu vaccines reached larger trials, and what were the serious side effect rates?
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Have any mRNA flu vaccines reached larger trials, and what were the serious side effect rates?
The short version: no mRNA flu vaccine has reached a large-scale trial with published serious adverse event rates. The evidence base is still tiny and mostly preclinical.
The largest human data comes from a 2017 phase 1 trial of H10N8 and H7N9 mRNA flu vaccines. It enrolled 23 people who got the shot and 8 who got placebo. There were 163 reactogenicity events, all mild, and no serious adverse events [5]. That is the entire human safety record. No larger trials have published results. The rest of the evidence is ferrets, mice, and lab assays [3, 4, 6, 8, 9, 10]. None of it answers your question about large-scale human safety.
The heart inflammation signal from the closely related mRNA COVID platform is the only large-scale safety data we have. A global database analysis found over 26,000 myocarditis reports and 22,000 pericarditis reports linked to mRNA COVID vaccines [11]. That is not flu-specific, but it is the only large human safety signal for the platform.
| Evidence | What it shows |
|---|---|
| Phase 1 mRNA flu trial | 23 people, no serious events [5] |
| Preclinical studies | Mice, ferrets, macaques only [3, 4, 6, 8, 9, 10] |
| mRNA COVID database | 26,670 myocarditis reports [11] |
My call: no mRNA flu vaccine has large-scale human safety data. The platform's heart inflammation signal is real. Confidence: low.
Sources used 13
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