Q Fever

Occupational risk groups in Australia: abattoir workers, livestock farmers, shearers, veterinarians, laboratory personnel handling C. burnetii. Travelers with planned agricultural/pastoral exposure in endemic regions (Australia, southern France, Spain, Netherlands, sub-Saharan Africa). Military personnel deployed to endemic areas. Pre-vaccination screening mandatory — skin test (CST) and serology required to exclude prior exposure.

Severe allergic reaction to previous dose or any component. Previous Q fever infection (confirmed or suspected) — vaccination of previously immune individuals can cause severe local reactions including sterile abscess, granuloma. Positive Q fever skin test (Coxiella Skin Test, CST ≥5 mm). Positive Q fever serology (IgG Phase I or Phase II ≥1:10). Pregnancy (insufficient data). Immunocompromised individuals (limited efficacy data).

Common (1–10%): injection site pain (40–50%), induration, erythema, headache, malaise, myalgia, fatigue. Uncommon: fever, lymphadenopathy. Rare but important: severe local reactions in pre-sensitized individuals (if screening omitted) — sterile abscess, granuloma at injection site. Chronic fatigue syndrome (Q fever fatigue syndrome, QFS): debated association, Australian studies suggest no increased risk with proper pre-screening.

Single 0.5 mL dose, subcutaneous injection (deltoid region). No booster recommended — single dose provides long-term immunity (≥5 years confirmed, likely lifetime). Must complete pre-vaccination screening 7 days before vaccination. Administer ≥14 days before potential exposure. Currently only available in Australia (special access in other countries).

Pre-licensure study (Marmion et al.): 100% efficacy in seronegative abattoir workers over 15 months. Australian post-marketing surveillance: vaccine effectiveness ~95–100% in occupational cohorts with >20 years follow-up. Single dose generates durable cell-mediated and humoral immunity. Seroconversion: >97% at 28 days post-vaccination.

Store at +2°C to +8°C. Do not freeze. Protect from light. Use within 6 hours of reconstitution. Shelf life: 36 months (lyophilized).

Limited formal interaction studies. Can be co-administered with other inactivated vaccines at different sites (based on general principles). No known drug interactions. Concurrent immunosuppressive therapy may reduce immune response.

Pregnancy: contraindicated (insufficient data, and pre-vaccination screening not validated in pregnancy). Breastfeeding: no data; inactivated vaccine expected to be safe, but withhold if possible. Risk-benefit if occupational exposure is ongoing.

Breastfeeding: Q-VAX® (inactivated) — there is insufficient data on its use during breastfeeding. As an inactivated vaccine, the theoretical risk to the breastfed infant is low. Coxiella burnetii can be shed in breast milk during active Q fever infection, which is a separate concern from vaccination. Breastfeeding women at occupational risk should discuss vaccination timing with their healthcare provider. Consider completing breastfeeding before vaccination if exposure risk allows deferral.

Not approved for children <15 years (Q-Vax). Limited safety and efficacy data in pediatric populations. Q fever is uncommon in children but does occur in rural/agricultural settings.

No specific dose adjustment. Elderly with occupational exposure history more likely to be seropositive — pre-screening especially important.

MANDATORY pre-vaccination screening: skin test (CST) + serology. Do NOT vaccinate without screening — risk of severe adverse reactions in pre-immune individuals. Screening protocol: blood draw for Q fever IgG/IgM serology AND intradermal CST (0.02 mL, read at 7 days). Only vaccinate if both negative. Post-vaccination: observe for 30 minutes. Injection site may remain tender for 1–2 weeks.