天然痘ワクチン

天然痘ウイルスを扱う検査室従事者、軍関係者、生物学的脅威対応チーム。

ACAM2000: severe eczema/atopic dermatitis (risk of eczema vaccinatum), immunocompromised persons (risk of progressive vaccinia), pregnancy (risk of fetal vaccinia), cardiac disease (myocarditis risk), household contacts with above conditions, breastfeeding, age <1 year. Jynneos: severe allergic reaction to previous dose or component; pregnancy (use only if benefit outweighs risk). ACAM2000 has significantly more contraindications than Jynneos.

ACAM2000: expected vaccination site reaction (papule → vesicle → pustule → scab over 2–3 weeks). Inadvertent inoculation to other body sites (face, genitals — 6/10,000). Generalized vaccinia (3/10,000). Myopericarditis (5.7/1,000, usually mild). Eczema vaccinatum (in eczema patients): severe, potentially fatal. Progressive vaccinia (vaccinia necrosum): in immunocompromised — potentially fatal. Jynneos: injection site pain (85%), redness, swelling, fatigue (30%), headache (18%). No myocarditis signal. No risk of progressive vaccinia (non-replicating).

ACAM2000: single dose via scarification (bifurcated needle, 15 punctures with vaccinia-containing droplet). Major reaction ("take") expected — vesicle/pustule at site. Check vaccination take at 6–8 days. Jynneos: 2 doses of 0.5 mL SC (not IM), 28 days apart. Previously smallpox-vaccinated: single Jynneos booster. ACAM2000 booster: every 3 years for ongoing risk (laboratory workers).

ACAM2000: historically ~95% effective against smallpox (pre-eradication data). Cross-protection against mpox: ~85%. Vaccination within 3 days of smallpox exposure prevents disease in most cases. Jynneos: see Mpox Vaccine entry for mpox effectiveness data. Orthopoxvirus cross-neutralizing antibodies: detectable in >95% after Jynneos 2-dose series.

ACAM2000: frozen at -15°C to -25°C. Reconstituted: use within 18 hours. Jynneos: frozen at -20°C (long-term) or +2°C to +8°C for up to 8 weeks.

ACAM2000: do not co-administer with live vaccines (including varicella, MMR) — risk of dissemination. Jynneos: standard live vaccine spacing (same day or ≥28 days for other live vaccines; any interval for inactivated vaccines). VIG (vaccinia immune globulin) is used to treat ACAM2000 complications — does not interfere with vaccination.

Pregnancy: ACAM2000 contraindicated (fetal vaccinia documented). Jynneos: limited data; use only in emergency when benefit outweighs risk. Breastfeeding: ACAM2000 contraindicated (live vaccinia in lesion). Jynneos: expected safe (non-replicating).

ACAM2000: not for <1 year. Jynneos: approved ≥18 years (US), ≥1 year (EU — as Imvanex). Pediatric ACAM2000 use only in emergency.

ACAM2000: vaccination site is INFECTIOUS until scab separates. Strict wound care: keep covered, wash hands, avoid contact with immunocompromised/eczema/pregnant individuals. Healthcare workers: may need reassignment during vaccination take. Jynneos: no wound care needed (no skin lesion). Both vaccines cross-protect against variola, vaccinia, and mpox. Pre-event vaccination (ACAM2000): use only in designated personnel — adverse events exceed benefit in general population.