---
schema_version: "secwatch.filing_event.v1"
accession: "0001193805-22-000672"
form_type: "8-K"
ticker: "ARCT"
cik: "0001768224"
company_name: "Arcturus Therapeutics Holdings Inc."
filed_at: "2022-04-20T23:59:59+00:00"
generated_at: "2026-06-26T06:14:48.741084+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# Arcturus ARCT-154 Phase 3 shows 55% efficacy vs COVID-19, 95% vs severe disease

## Summary
- Two 5-mcg doses of ARCT-154 provided 55% efficacy (95% CI 46.9-61.9) against symptomatic COVID-19.
- Vaccine demonstrated 95.3% efficacy (95% CI 80.4-98.9) against severe COVID-19 including deaths.
- No cases of myocarditis or pericarditis reported; unsolicited adverse events comparable to placebo.
- Data submitted to Vietnam Ministry of Health for EUA; ARCT-154 advancing to pivotal booster trial in major markets.
- Also amended loan with Western Alliance Bank to extend interest-only payments to Aug 1, 2022, and terminated Israeli supply deal for first-gen vaccine (no penalty).

## SEC filing metadata
- accession: 0001193805-22-000672
- form_type: 8-K
- ticker: ARCT
- cik: 0001768224
- company_name: Arcturus Therapeutics Holdings Inc.
- filed_at: 2022-04-20T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 1.01, 1.02, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1768224/000119380522000672/0001193805-22-000672-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1768224/000119380522000672/e621578_8k-arct.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193805-22-000672
- JSON: https://secwatch.observer/filing/0001193805-22-000672.json
- Plain text: https://secwatch.observer/filing/0001193805-22-000672.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.