Limitations of this study
The application of a cross-sectional pattern basically does not allow reliable statements about cause-effect relationships. The study also fails to provide information on the number of vaccination doses administered (complete vs. incomplete basic immunisation vs. booster vaccination) or on the time at which HAV or HBV vaccination may have been given (e.g. being vaccinated as a child, before taking up employment or before starting career). The questionnaire did not contain validated questions, for it has been developed by the Institute of Teachers' Health. It was previously used in the special school study by Claus et. al. (2014). Due to the retrospective data collection, bias in the information on HAV or HBV infection or vaccination cannot be excluded (recall bias). As a matter of principle, when interpreting the data and comparing them with other data sources, the relevant collection method must be taken into account (self-disclosure vs. vaccination record vs. determination of serostatus). The comparison of study participants and non-participants showed significant age differences. Corresponding age effects must therefore be taken into account when interpreting the data. However, the strength of this study lies in the high and representative participation rate.
HBV hazards in the workplace
Various studies have previously investigated the prevalence of HBV infections or the seroprevalence of HBV in institutions for the disabled. Most studies found a higher proportion of post-infection conditions (anti-HBc positive) in mentally impaired residents compared to the general population (6–10). Increased HBV seroconversion rates among teachers have also been described previously, assuming the presence of HBV carriers among pupils (3, 2).
In 2015, the WHO estimated that 3.5% of the population worldwide live with chronic HBV infection (11). According to Poethko-Müller et al. (12), the serostatus in a Germany-wide sample showed HBV infection in approximately 5.1% of adults. Similar studies from other countries presented comparable information (13, 14). In the present study, 1.1% and 1.6% of the respondents stated that they had had HBV and HAV respectively. This discrepancy could be due to the limitation of this study, namely that only self-reports are available but no serological evidence is. In addition, HBV may have a subclinical course.
In the present study, 94.7% − 98.1% of all respondents stated that they were treating injuries among pupils, the majority (70.9–81.8%) 1–2 times a month or less. These findings support the recommendation of the German Standing Committee on Vaccination (STIKO) that company first aiders, who are classified by the Committee on Biological Agents (ABAS) of the German Federal Ministry of Labour and Social Affairs (BMAS) as an occupational group with an increased risk of infection, be vaccinated against HBV (15). However, with regard to first aid activities, there is currently a lack of data to show that there is an increase in the number of accidents in special schools compared with the general population.
Both, teachers and educational staff, support their pupils in taking medication. This also includes the administration of injections. However, it has not been clarified whether these invasive activities are associated with an increased risk of needlestick injuries. Assuming increased incompliance and decreased impulse control among pupils in care, aggressive behavior such as scratching, biting, or spitting by pupils is not negligible as a potential risk of infection from injury and is reported from all special schools, regardless of the special focus of support. Remis et. al. previously described transmissions of HBV from mentally retarded pupils to their teachers. The risk of infection for teachers who report student contact in the classroom is found to be increased more than fourfold. (16) Accordingly, the results of this study indicate that employees at special schools are at increased risk of HBV infection and that hepatitis B prophylaxis is likely to be required.
HAV hazards in the workplace
Pupils with mental or physical disabilities are diapered, washed, fed, probed and catheterized by the staff. The regular performance of these activities entails a risk of infection for pathogens that are excreted via the stool. Possible contact can occur here, for example, during assisted toilet use, incontinence care or intimate hygiene. Nevertheless, contact can also occur with nasal secretions, saliva or infected blood during wound care. Claus et al. showed that many pupils at special schools with focus on mental or physical disabilities could not follow elementary hygiene rules, so that body excretions remain on hands, body and objects. There would therefore be an uncontrollable, increased risk of both contact and smear infections and those transmitted via droplet infection (5).
According to the results of the present study, almost all employees working at special schools with a focus on mental or physical disabilities assist pupils with toilet visits and intimate hygiene at least once a year. Almost every second employee take part in this activity on a daily basis. At special schools with a focus on social-emotional disabilities and with interdisciplinary focus, this applies to significantly fewer workers overall and predominantly to the educational staff. The frequency of diaper changes is generally lower. The relative distribution of these activities between the occupational groups is comparable at all schools, irrespective of the support focus. However, activities with risk of infection such as catheterization, which one would rather expect in mentally or physically impaired pupils, are also carried out in schools with a focus on social-emotional or interdisciplinary focus, although to a much lesser extent.
In the context of the present survey, about 10% of the employees at special schools with a focus on mental or physical disabilities perform catheterization, predominantly by educational staff. In contrast, 26.2% of the respondents in the study of Claus et al. (5) stated that they catheterized pupils. This difference could be caused by the fact that the study by Claus et al. was based on a self-selective sample of special schools, resulting in the participation of schools mainly for pupils with severe disabilities.
Overall, the activities mentioned here involve contact with potentially infectious faeces or bodily fluids and form part of the activities of all employees of all special schools, regardless of their specialisation. This makes preventive occupational health care including infection prevention counselling and vaccination against HAV highly relevant.
Based on the self-declarations, vaccination rates of 57.7% (HAV) and 64.3% (HBV) could be determined in this study. Claus et al. (4) also reported similar vaccination rates of 42.0% (HAV) and 80.1% (HBV) based on vaccination passports and serostatus, which appear to be higher overall than those reported by Poethko-Müller and Schmitz (12) for the population-wide sample. The finding of the highest HBV vaccination rate in the group of 20 to 29-year-old persons in all studies is probably a consequence of the vaccination recommendation for infants and children recommended in 1992 by the WHO and issued in Germany in 1995. Moreover, the differences in vaccination rates may be caused by socio-economic effects. For example, Poethko-Müller and Schmitz (12) found higher vaccination rates among persons with a higher social status.
In the present study, logistic regression analyses were used to determine age, school’s focus of support and participation in vaccination counselling within the past 5 years as significant predictors of HAV and HBV vaccination. For the HBV vaccination, gender, participation in infection protection advice, support of pupils in toilet visits and intimate hygiene were determined as additional significant predictors. Similarly, Claus et al. (4) found a significantly higher vaccination rate (82.6% vs. 71.8%) for HBV for respondents who change diapers compared to respondents who do not change. Staff seem to associate taking on nursing tasks such as changing nappies or assisting schoolchildren with toileting or intimate hygiene with the risk of HBV infection, even though the tasks themselves are mainly associated with the risk of HAV infection. At this point, it is not clear whether the decision to be vaccinated is influenced by subjective risk perceptions or whether this is due to structural guidelines or processes for risk assessment in schools based on corresponding activity or job-related selection mechanisms.
Analogous to the relevant influencing factors identified in the present study, Claus et al. (4) also pointed out that HAV vaccination is more likely if the employees have been informed about infectious diseases and vaccination protection before they start work. According to the present study, explicit vaccination counselling is more likely to be taken up and has a greater influence on vaccination rates than general infection protection instruction. A certain biasing influence due to the different reference periods (vaccination counselling within 5 years vs. infection prevention instruction within 2 years) cannot be excluded at this point.
However, the prevalence of HBV infections in persons over 20 years of age has not been significantly reduced even after the introduction of vaccination (Kwon und Lee 2011). In addition various studies have shown that the response rate to HBV vaccination may depend on a number of factors (17–21). Therefore, the immune status of persons at increased risk of infection should be assessed and, if necessary, boostered (22).
In principle, the results clearly show the need for counselling and information. In their systematic review, Jarrett et al. (23) state that the most effective way to increase vaccination rates is to target under-vaccinated members of specific populations with strategies that focus on increasing vaccination knowledge and awareness and to simplify access to vaccination.