Overview of the Implementation of the First Year of Immunization against Human Papillomavirus across Different Administrative Units in Serbia and Montenegro

"It is essential to address...challenges effectively in future national strategies, leveraging media, especially electronic platforms, to counter misinformation and promote evidence-based information about the HPV vaccine."

Developing countries, such as Serbia and Montenegro, have a moderate to high burden of incidence and mortality of cervical cancer. In these countries, healthcare resources may be limited, leading to challenges in implementing comprehensive cervical cancer prevention and control measures. This study analysed coverage of HPV immunisation during the first year of the immunisation programme and the sociodemographic characteristics across different administrative units in Serbia and Montenegro.

The study used depersonalised coverage data from the National Immunization Registries of the Public Health Institute of Serbia and Institute of Public Health of Montenegro, which contain data on vaccinated girls with the HPV vaccine. Data were collected for one year from the time of the introduction of nine-valent HPV vaccine at the national level, i.e., from June 2022 in Serbia and from February 2023 in Montenegro. In addition, Serbia initiated HPV vaccination, adopting a gender-neutral strategy for ages 9-19 without prior campaign or promotion. In contrast, Montenegro focused initially on 9-year-olds with extensive promotional and educational efforts. It was not until February 2023 that Montenegro expanded its vaccination programme to include ages 9-14.

The researchers analysed coverage in cohorts of girls aged 9 to 14 years, 15 to 19, and 9 to 19 years in Serbia and of girls aged 9-14 years in Montenegro for the mentioned period. The analysis of vaccine coverage was based on the initiated HPV immunisation, i.e., every child who received at least one dose of the vaccine was considered vaccinated, in both countries. The coverage by administrative units was calculated by dividing the number of vaccinated female persons by the number of female persons in the observed cohorts according to the population census.

Coverage of HPV vaccination in Serbia for females aged 9-14 and 15-19 years was 5.5% and 5.9%, respectively. The coverage rate of immunisation against HPV in Montenegro for girls aged 9-14 years was 22.1%. Within Serbia, only one administrative region (Moravica) had HPV immunisation coverage in girls 9-19 years old above 10%, possibly because epidemiologists from the local public health department had a more prominent presence in local media and communication with schools and healthcare workers in their district compared to other districts. (In Serbia, 11 districts had coverage from 5 to 10%, and 13 districts had coverage below 5%.) In Montenegro, two administrative units, Cetinje and Berane, reported the highest coverage, with 39% and 36.4% of vaccinated eligible girls, respectively.

When the researchers explored the coverage of HPV immunisation among girls aged 9-19 years across different regions in Serbia, they observed that the level of coverage did not correlate with the number of paediatricians or with population density. In Montenegro, they observed a similar situation. On the other hand, they found a statistically significant moderate negative correlation between HPV immunisation coverage and the percentage of illiterate women in the administrative units. That is, in the administrative units in Serbia that fall into the third tertile for the variables "Educational attainment of females aged 15 and up: Without or incomplete primary education" and "Illiterate female population aged 10 and up", the mean values of average immunisation coverage are lower compared to the other tertiles. This finding indicates that illiterate individuals might be harder to reach and inform about vaccination.

Reflecting on the findings, the researchers point to the process of introducing the HPV vaccine at the national level, which differed significantly between the two countries. As noted above, in Serbia, the HPV vaccine was introduced abruptly, without prior national promotional campaigns. On the other hand, Montenegro had established a structured approach to prepare the intended population for the vaccine's introduction. Extensive educational campaigns, expert media coverage, school visits, and communication with parents preceded the vaccine's introduction. These activities included involving epidemiologists and healthcare workers in promoting and emphasising the vaccine's importance to the public. In addition, financial incentives were provided to those involved in administering the HPV vaccine. These factors, rather than the number of paediatricians, population density, level of education, and other sociodemographic variables investigated in the study, appear to have had a more significant influence on the level of HPV immunisation coverage.

The findings highlight the need for targeted interventions, such as comprehensive educational campaigns and community engagement efforts, particularly in regions with higher illiteracy rates. In addition, addressing common concerns about the vaccine - like fear of side effects, perceptions of it being new or experimental, and doubts about safety and necessity - can further improve vaccination rates. There should also be a concerted effort to engage more healthcare workers in educational campaigns tailored for schools in every county. The goal is to ensure that every parent receives crucial information about HPV vaccination directly through the school system. Epidemiologists responsible for each district should have digital information on the number of vaccinated persons, gender, and place of residence, and then they should analyse vaccination rates more frequently to identify districts with low vaccination coverage. Such an analysis would guide the strengthening of targeted promotional campaigns in those specific areas.

In conclusion, taking into account the experiences in Montenegro, increasing immunisation coverage in Serbia could be achieved through a more vigorous educational campaign reaching schools, the general population, and healthcare workers, as well as by additionally incentivising those engaged in these activities. Also, in Serbia, utilising electronic media channels could enhance the visibility and understanding of HPV vaccination among the public. This approach could ensure that key messages about the vaccine's benefits and availability are widely accessible, thereby fostering increased vaccination rates nationwide.

Full list of authors, with institutional affiliations: Mirjana Štrbac, Institute of Public Health of Vojvodina; Milko Joksimović, Institute of Public Health of Montenegro; Vladimir Vuković, Institute of Public Health of Vojvodina and University of Novi Sad; Mioljub Ristić, Institute of Public Health of Vojvodina and University of Novi Sad; Goranka Lončarević, Institute of Public Health of Serbia "Dr Milan Jovanović Batut"; Milena Kanazir, Institute of Public Health of Serbia "Dr Milan Jovanović Batut"; Nataša Nikolić, Institute of Public Health of Vojvodina and University of Novi Sad; Tatjana Pustahija, Institute of Public Health of Vojvodina and University of Novi Sad; Smiljana Rajčević, Institute of Public Health of Vojvodina and University of Novi Sad; Stefan Ljubičić; Institute of Public Health of Vojvodina; Marko Koprivica, Institute of Public Health of Vojvodina; Dragan Laušević, Institute of Public Health of Montenegro; Vladimir Petrović, Institute of Public Health of Vojvodina and University of Novi Sad