Study setting

This study focused on the public health landscape in Germany, a politically stable, high-income country located in Central Europe. In Germany, the responsibility for public health planning and decision-making largely falls to the federal states. These subnational entities possess their own governments and parliaments, allowing for regional autonomy in a wide range of policy areas while operating within the overarching national health framework.

In April and May 2021, about 14 months after the introduction of the mandate and the onset of the COVID-19 pandemic in Germany, we conducted online interviews with employees from different LHDs to explore their opinions on and experiences with the implementation of the measles vaccine mandate. While one interview involved two employees from the same LHD, all other interviews were conducted as one-on-one meetings.

Study participants and recruitment

The study sample consisted of employees from German LHDs who were directly involved in the implementation of the measles vaccine mandate, herein referred to as experts due to their specialized knowledge and pertinent experiences [13]. All participants were required to be at least 18 years old. To assemble the study sample, purposive sampling was employed. Potential participants were approached during two separate public health conferences related to vaccination efforts in March and April 2021, where the planned study was presented and participation was encouraged. Interested individuals were invited to contact the research team via a study-specific email address. The final sample included 17 experts representing 16 different LHDs across 10 German federal states (Fig 1).

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Fig 1. Localization of the 16 participating local health departments in Germany.

https://doi.org/10.1371/journal.pone.0306003.g001

Data collection

Data were collected within online semi-structured interviews via WebEx, guided by an interview protocol consisting of open-ended questions (S1 Appendix). Semi-structured interviews are based on a catalog of questions, which, however, can be flexibly adapted to the interviewee and the flow of the interview to investigate the research interest in greater depth based on the responses given [14]. Accordingly, a modification of the order of topics or additional follow-up questions were possible [14]. The interview guide was developed by a team of researchers with expertise in immunization programs and evaluation research. The following topics were covered by the guide: (1) planning and preparation of the mandate, (2) implementation of the mandate (proof of immunity), (3) communication and counseling, (4) parental acceptance of the mandate, (5) implementation of the mandate (sanctions), (6) impact of the COVID-19 pandemic, and (7) strengths and weaknesses of the mandate. The development of the interview guide followed the SPSS principle (collect, check, sort, and subsume) by Helfferich [15]. The instrument was pretested within the study team and with two individuals from the target population to validate its logic and comprehensibility. Study participants were provided with a summary of the main topics prior to the interviews.

The interviews were conducted by the first author (SW, female, trained and experienced in qualitative research methods), who had no contact with any of the interviewees prior to this study. All interviews were conducted in German, audio-recorded using an encrypted voice recorder, and transcribed verbatim following the basic transcription system of Dresing and Pehl [16]. Interview lengths varied from 30 to 90 minutes. During transcription, any information that could potentially allow a direct link to an individual was anonymized. Participants could request a transcript of their interview, fostering transparency and participant validation of the data collected.

Data analysis

Data analysis was conducted using the Framework method, a specific approach to qualitative content analysis, to systematically manage and analyze the qualitative data [17]. The thematic categories (codes) were deductively derived from the structure and content of the interview guide. A coding tree, which organizes codes hierarchically, facilitated the systematic application of the established codes to the interview transcripts, enabling the identification of relevant text segments. All interview transcript excerpts relevant to our research interest were generalized and summarized in a stepwise process. The aggregated study results on the main themes and associated sub-themes were organized in a matrix with the dimensions “cases x categories”. This organization allowed for the comparison and interpretation of data across cases as well as across categories within a single case [17]. To ensure consistency, the interviewer (SW) coded and analyzed the data. Data management and analysis were facilitated by the software MAXQDA.

Ethics

Participation was voluntary. All study participants received detailed study information by mail prior to data collection, which outlined the study’s objectives, procedures, ethical considerations, including confidentiality measures, and emphasized the voluntary nature of participation. The interviews were based on written, informed consent. There was no compensation for study participation.

The study’s protocol and related documents received approval from the data protection officer of the Robert Koch Institute, ensuring adherence to data protection standards. Given that this study did not involve the collection or analysis of sensitive personal data beyond the professional role, the research project did not require the oversight of an ethics committee according to German regulations. This exemption applies as this study did not engage with areas mandatorily subject to ethics committee approval in Germany, such as studies involving drugs, biologics, medical devices, clinical trials, the use of human biological materials, genetic research, or studies on embryos, stem cells, and cloning, as stipulated by the Drug Law, the Medicinal Products Law, and the Medical Device Law Implementation Act, among others. We confirm that all research methods were conducted in accordance with the relevant guidelines and regulations, ensuring ethical integrity. The reporting of this study was guided by the Consolidated Criteria for Reporting Qualitative Research: 32-item checklist [18].

Implementation of the measles vaccine mandate

This section provides a summary of how the experts described the implementation process of the measles vaccine mandate. Typically, the proof of immunity is initially checked in the relevant facilities, such as schools, preschool childcare centers, and healthcare facilities. The results are documented and the individuals who did not provide immunity evidence are reported to the responsible LHD. In instances of ambiguous vaccination cards, medical certificates (e.g., for contraindications) or laboratory reports (e.g., for antibody verification), the facilities are often supported by the LHD in the verification process. LHDs are responsible for documenting and addressing reports of absent immunity proofs from institutions. Most interviewees indicated that they do not have a complete overview of the extent of missing proofs. Many institutions had not yet reported to the LHDs at the point of data collection, possibly due to the transition period, leading experts to speculate that several institutions had not yet initiated immunity proof verification. Conversely, some facilities had completed this process and informed the LHDs of any missing proofs. Some study participants speculated that the extent to which immunity was already being checked depends on the facility management’s stance on the mandate and its perceived significance.

As of the data collection period, about two-thirds of interviewees were engaged in addressing instances of missing immunity proofs, adopting a phased approach. Initially, LHDs remind the individuals in question of their obligation via phone or mail. Following this, multiple reminders are usually sent, sometimes specifying deadlines and hinting at possible sanctions. A few experts mentioned offering personal consultations. Other LHDs did not provide in-person counseling due to the pandemic or a lack of personnel resources.

Most participants had not yet enforced sanctions at the time of data collection, which become relevant if immunity proofs remain unsubmitted despite several reminders. The approach to processing the reports and enforcing sanctions varied across LHDs. Several study participants noted that sanctions are typically enacted by an authority other than the LHDs, such as the regulatory office. In some LHDs, it was still unclear how to apply sanctions, with unresolved questions about, for example, the amount of the fine. Other interviewees indicated values between EUR 1,000 and 2,500, noting differences between different groups of people or increased fines for repeated requests.

For most study participants, limited time was available to implement the measles vaccine mandate, for example due to the pandemic. However, for other experts, activities related to the mandate took up a large part of their work within the LHD. The amount of work associated with the mandate was observed to fluctuate over time and was expected to increase significantly after the transition period ends and individuals who were either employed or under care before March 2020 will be required to provide proof of their immunity.

Challenges in the implementation of the measles vaccine mandate

Many experts pointed to the prevalent uncertainty around the mandate’s implementation procedures as a significant challenge. This uncertainty encompassed issues such as handling fraudulent medical certificates and determining the course of action for imposing sanctions, including defining responsibilities and setting the amount of fines. Such ambiguity led to considerable differences in how different LHDs executed the mandate. Many interviewees felt left alone with these questions and criticized the lack of designated contacts and support from higher-level institutions.

„The main problem […] is that the support for these problems that arise in everyday life is basically not there or is much too slow. In other words, there is no contact person who can really explain in a timely manner: this is how we can deal with it. Or that there is simply far too little feedback—How should we implement it? How should we deal with these problem cases […]?" (Participant 5, physician, female)

The interviewees reported that the prevailing legal framework allows every LHD to adopt a different approach to the implementation of the measles vaccine mandate. Consequently, many study participants advocated for the establishment of standardized procedural instructions or guidelines for the whole country or at least within each federal state. It was pointed out several times that considerable regional differences in the implementation of a national policy are not appropriate and could lead to lower acceptance by the public.

The capability of facilities to verify immunity and report absent proofs was reportedly limited by the fact that non-medical personnel may lack the expertise to scrutinize vaccination cards and medical certificates adequately. Reportedly, this limitation resulted in the acceptance of potentially fraudulent documents. Fraudulent certificates are incorrect medical certificates (often vaccination or test certificates for communicable diseases) issued by a medical professional. Dealing with this type of medical certificate was described by almost all interviewees as a major challenge.

„In the neighboring county, there was a doctor working in a private practice […] They have issued umpteen certificates, both for the mask exemption and of course for the exemption from the vaccination obligation. That has been quite lucrative: a certificate costs 300 euros there. […] People traveled from the Allgäu and from Thuringia and from hundreds of kilometers away […] This certificate is formulated so that they certify not only an individual contraindication against a measles vaccination, but the formulation that this person may not be vaccinated at all with any vaccine now and in the future.” (Participant 7, physician, male)

Some experts noted that they were internally ordered not to doubt apparent fraudulent certificates principally. Other interviewees reported fraudulent documents or the physician who issued the fraudulent certificates to the state medical association. In this context, it was often noted that there would always be groups of people who will not be persuaded to get vaccinated and will evade their obligation to provide proof.

„And the opponents of vaccination, to be honest, they cannot be caught by any mandate in this world. That is my personal conviction. So, that one assumed: now all [parents] have their children vaccinated—this is not going to happen.”(Participant 12, specialist in social medicine, female)

Several experts suspected that the actual extent of vaccine-critical individuals would become apparent after the transition period has expired, as some individuals refer to this deadline and refuse to submit the proof earlier.

The participating experts reported few challenges in the interaction with parents of children attending school or preschool childcare as one of the largest groups affected by the mandate. However, they identified different levels of difficulty depending on whether the child had already been vaccinated, had simply not been vaccinated because the parents had forgotten, or whether the parents were opposed to vaccination. Parents of vaccinated children, and thus the majority, did not seem to have any problems with the mandate.

„The vast majority [of parents is] uncritical, because the majority is vaccinated. […] Those who have vaccinated their children do not find it dramatic, because they have to show the vaccination card anyway, for example at the school entry examination. So it is nothing out of the ordinary for parents who have already taken children through such a procedure at some point. Many also think it is good that it is now mandatory.”(Participant 12, specialist in social medicine, female)

Parents who have simply forgotten their obligation to provide proof usually complied after the first request. LHDs also had to deal with people with a vaccine-critical attitude, who feel that their fundamental rights are being restricted, regard vaccination as bodily harm, engage in lengthy discussions or threaten legal action. However, extreme negative parental reactions were described to be rare.

„I would say [that vaccine-critical attitudes are] fortunately not common. But when [they are vaccine opponents], they are real [opponents]. So these are parents who make it very clear to us on the phone, in the first meeting what they think of the whole issue. At times, discussions extend beyond factual matters into personal territory. So I also had to end a phone call […] because it was no longer on the same level, the conversation with the mother.”(Participant 11, specialist in social medicine, female)

Impact of the COVID-19 pandemic on the implementation of the measles vaccine mandate

According to most experts, the impact of the COVID-19 pandemic on the implementation of the measles vaccine mandate was substantial. Infection control activities often occupied the majority of the working hours in the LHDs. As a result, regular activities, including the implementation of the mandate, were often put on hold or, in some cases, completely suspended for certain periods. Since the COVID-19 pandemic reached Germany at about the same time as the mandate came into effect (in March 2020), meetings, working groups, and preparations that had been planned for the mandate were often canceled. According to the experts, the implementation of the mandate was immediately displaced by the pandemic in both public awareness and prioritization in the LHDs.

Some experts feared that the pandemic could also have a negative impact on vaccination rates for other infectious diseases (such as measles), further undermining the intention of the mandate. One of the reasons given was that doctor visits were less frequent and, accordingly, the vaccination status for infectious diseases besides COVID-19 was less likely to be checked and completed. Furthermore, parents were sometimes unable to provide proof due to COVID-19-related infection control measures, such as school closings. These circumstances often delayed the check for immunity.

A few interviewees reported that their work was not or only slightly affected by the pandemic, mostly because they were not assigned or only partially assigned to COVID-19-related activities. Positive effects of the pandemic were rarely mentioned, including an increase in public support for the measles vaccine mandate and a shift in attitudes towards vaccinations in general.

„It [the mandate] has experienced a higher level of acceptance. I am convinced that the danger or the value of infectious diseases has now come into consideration again for the first time in this generation. […] I believe that this actually means a rethinking in the direction of vaccination in general as well. People will think much more about: how can I avoid diseases? Perhaps, I hope in any case, this will also have an effect on the existing vaccinations, so that the willingness to vaccinate will at least remain at the same level or even increase.”(Participant 16, physician, female)

Experts’ attitudes towards the measles vaccine mandate

Most experts suspected that the measles vaccination rate would be increased through the mandate and that some vaccination gaps would be closed. Some experts even suggested that the new legislation is the only way to increase measles vaccination rates. It has been noted that it has brought more attention to measles and vaccinations in general, and has highlighted their relevance.

„Basically, I think it is a nice thing to show people that this is really important. […] Sometimes it is also easier if you are not given a choice, but are simply told: do this, do that.” (Participant 4, physician, female)

Some interviewees reported their work becoming easier due to the mandate, since the legal basis clearly regulates the obligations of the parties involved. Furthermore, the legislation emphasizes the social responsibility of citizens in preventing infectious diseases.

„But overall I think it [the mandate] is good. Because I think that at the moment we are developing a bit socially in a direction where everyone knows their rights, but the duties that you also have in a community are being neglected a bit.”(Participant 14, physician, female)

However, others were more hesitant, as they saw alternative approaches or necessary supplements to the mandate, such as more intensive public relations work, reporting, education, and regular, easily accessible vaccination campaigns.

„I would rather like to put the energy I am putting in here now into a vaccination campaign or into a medical activity in schools with vaccination counseling […]. With the same effort, I could visit every school in our county over the year and do at least one vaccination consultation with simultaneous vaccination of those who are in default [with their vaccination]. […] Then this would actually be an action and not just an administrative activity.” (Participant 16, physician, female)

The experts also expressed their opinions on the imposition of sanctions in the context of the mandate. Almost all participants considered sanctions appropriate and effective. They mentioned that penalties are necessary to make people act and to give the mandate a certain importance. In particular, people who have forgotten about vaccination or have not yet taken care of it were reached by the sanctions and reminded with pressure.

„I have now learned in the process that with certain people who, as I said, need […] [a bit pressure], I would say that fines make sense. Something only happens when there is pressure. And I would also take advantage of that. That has to happen, because it is about the well-being of the child. So you can push the parents in the right direction and that can also cost [them] something.”(Participant 16, physician, female)

In some cases, experts pointed out that individuals with well-founded fears, possibly stemming from negative experiences with vaccinations, might be reluctant to vaccinate their children. For these people, the imposition of sanctions was considered problematic. Some experts were ambivalent about the sanctions.

„I personally think that sanctions do not really reach people, on one hand. But on the other hand, you kind of need a plan so that it is taken seriously at all. And also with regard to people who make the effort and who stick to it and who participate. It would be unfortunate if they get the impression: we stick to it, we do everything / or even the facility managers: we make the effort and check it, and if you do not care, then it does not matter. […] And in order to attach a high value to it [the mandate], it is not possible without imposing sanctions.” (Participant 8, physician, female)

Other interviewees were fundamentally critical of sanctions and doubted that people would be persuaded to vaccinate because of a fine. They would prefer to rely on enhanced public relations efforts and to increase vaccination willingness through more extensive education and counseling. There was also frequent criticism that wealthier parents of school-aged children can buy their way out of the obligation because of the priority given to compulsory schooling, and that financial penalties in this context are ineffective.

Limitations

This study examines the implementation of a new German vaccine mandate to strengthen measles prevention, provides new insights into the operational work of the public health service, and highlights the need to harmonize the implementation of health policy measures among executing entities.

However, some limitations need to be considered. The interviewees were asked about past situations and activities. Retrospective assessment is inherently associated with difficulties because interviewees may not or may only partially remember all events correctly [35]. Memory gaps or false memories are difficult to assess or recognize by outsiders, but the potential for this bias must be taken into account. In general, using self-generated samples carries a risk of selection bias. Individuals who have agreed to participate in the study may systematically differ from non-participants, for example, in their attitude toward the measles vaccine mandate. The first author (SW) solely analyzed the data, including category construction and coding, and the coding process was conducted once. Since only one coder was involved, intercoder reliability does not apply. The study did not assess intracoder reliability, potentially affecting the consistency of coding over time. However, since the analysis was less interpretative than summarizing and structuring the interviewees’ statements, we suggest that this limitation does not significantly diminish the results’ conclusiveness.