Control strategies for Q fever based on results of pre‐vaccination screening in Victoria, 1988 to 2001

Abstract

Objective: Data from Q fever prevaccination screening were analysed to determine the level of agreement between the two tests of immunity and between disease or vaccination history and immunity, trends in proportion of participants immune to Q fever, and the annual risk of infection. Method: Data from nearly 10,000 screening episodes between July 1988 and June 2001 on Victorian workers at high risk were assessed. Results: Most participants were male (86%) and employed in Victorian abattoirs (81%). Agreement between results of tests for immunity was ‘fair’ (k=0.52). Selfreported history of vaccination or infection was a poor predictor of immunity. The proportion of positive blood and skin tests increased with years of exposure to animals/meat, but decreased over the 13‐year period with shorter exposures. Hence the percentage requiring vaccination increased from 50% in 1998 to 90% in 2001. The average annual risk of infection among abattoir workers was 45.0 per 1,000 (95% CI 42.3–47.6), and 62.6 per 1,000 (95% CI 57.5–67.7) over the first 10 years of exposure. Conclusions: This is the first Australian study to estimate the annual risk of Q fever infection in abattoir workers. The study confirmed previous findings of poor agreement between screening tests and predictive value of history of vaccination/exposure. Up to 90% of new entrants in high‐risk workplaces will be susceptible to Q fever and require vaccination. Implications: Systematic post‐marketing surveillance is needed to monitor adverse events to the vaccine, duration of protection and possible reasons for vaccine failures.

Adverse events and association with age, sex and immunological parameters of Q fever vaccination in patients at risk for chronic Q fever in the Netherlands 2011

“…The discordance of positive skin test and absence of antibodies (207; 12%) confirms previous observations [35]. Skin test did not lead to any ST-related SAE.…”

A serosurvey of Coxiella burnetii infection in children and young adults in South West Queensland

“…An economic evaluation of Q fever vaccination used an estimate 30 infections per 1,000 per year 20 . A similar rate (45.0 per 1,000) was found in Victorian abattoir workers 21 . The seropositivity in this study was 11.7% (1076 of 9196), similar to our finding of 11.0% in those aged 15‐24.…”

“…The incidence for the 15-24 age group using the following formula, where p age (15)(16)(17)(18)(19)(20)(21)(22)(23)(24) and p age(0-14) are the average prevalences for ages 15-24 and 0-14 respectively, and age difference is average age for the 15-24 group minus the average age for the 0-14 group. 6…”

Seroprevalence of Q fever among metropolitan and non‐metropolitan blood donors in New South Wales and Queensland, 2014–2015

“…First, antibody levels decline with time; only 10% of vaccinated participants and 39% of people with a history of Q fever in our study were seropositive. Seropositivity is therefore a poor marker of immunity, highlighting the importance of a good clinical history when screening for vaccination eligibility, as the performance of the skin test as a predictor of immunity also varies . Nevertheless, although 90% of vaccinated participants were seronegative, no‐one who had been vaccinated had been diagnosed with Q fever, consistent with reports of high vaccination effectiveness .…”

“…The value of notification data for informing vaccination policy is further limited because data on the vaccination status, occupation, and exposure history of patients are not routinely collected . Infection risk can also be measured by serosurveys, but most Q fever serosurveys in Australia have been of occupational groups at high risk, such as abattoir workers or farmers . Localised outbreaks suggest that living or working near certain types of industry may also play a role .…”