Introduction. Diphtheria is an acute respiratory infection caused by the gram-positive bacillus Corynebacterium diphtheria. Diphtheria can manifest with various clinical manifestations ranging from diphtheria of the skin, diphtheria of the eye, nasopharynx, and tonsils to severe respiratory tract infections. Due to the strong exotoxin produced by this bacterium, complications can occur in some organs and organ systems (myocarditis, neuritis, paralysis). It is very important to treat patients with antibiotics and diphtheria antitoxin to reduce the effect of the exotoxin produced by this pathogen. As a preventive measure, the vaccine should be administered in childhood from the age of one. A booster vaccination is given at 2, 7, and 14 years of age. Objective. To determine whether the regular administration of the diphtheria vaccine is carried out according to the mandatory vaccination calendar on the territory of the Šumadija District in Serbia and to compare the results obtained for the period before, during, and after the COVID-19 pandemic. Results and Discussion. Thanks to mandatory vaccination, the morbidity and mortality of children have decreased, and in our country, this serious infection has almost disappeared, i.e. eradicated. In many countries in Asia and Africa, there are cases of occurrence and spread of diphtheria during the year. The study is based on the processing of statistical data for the period 2018 to 2022. During the pandemic caused by the Coronavirus (COVID-19), there was a standstill in health services and interruptions in health care at the primary healthcare level. It was also observed that the percentage of vaccinations administered decreased in the calendar years during the pandemic and immediately after COVID-19. For the period from 01.01.2020 to 31.12.2020, a significant decrease in booster vaccination against diphtheria from 98% to 72% among 7-year-olds and from 96% to 86% among 14-year-olds was observed on the territory of Šumadija District compared to 2018, the period before COVID-19. Conclusion. It is to be feared that the disease, which can assume epidemic proportions due to its easy transmissibility and spread, will re-emerge. Healthcare professionals and the population should continue to be educated about the importance of mandatory vaccination according to the childhood vaccination calendar.

1. N. C. Sharma et al., “Diphtheria,” Nat. Rev. Dis. Primers, vol. 5, no. 1, 81, Dec. 2019.
   DOI: 10.1038/s41572-019-0131-y
   PMid: 31804499
2. A. Lamichhane, S. Radhakrishnan, “Diphtheria,” in StatPearls [Internet], Treasure Island, FL, USA: StatPearls Publishing, Jan. 2024.
   PMid: 32809746
3. M. Muscat, B. Gebrie, A. Efstratiou, S. S. Datta, D. Daniels, “Diphtheria in the WHO European Region, 2010 to 2019,” Eurosurveillance, vol. 27, no. 8, 2100058, Feb. 2022.
   DOI: 10.2807/1560-7917.ES.2022.27.8.2100058
   PMid: 35209973
   PMCid: PMC8874865
4. C. Jarrett et al., “Strategies for addressing vaccine hesitancy - A systematic review,” Vaccine, vol. 33, no. 34, pp. 4180 – 4190, Aug. 2015.
   DOI: 10.1016/j.vaccine.2015.04.040
   PMid: 25896377
5. P. Aaby, H. Ravn, C. S. Benn, “The WHO Review of the Possible Nonspecific Effects of Diphtheria-Tetanus-Pertussis Vaccine,” Pediatr. Infect. Dis. J., vol. 35, no. 11, pp. 1247 – 1257, Nov. 2016.
   DOI: 10.1097/INF.0000000000001269
   PMid: 27753772
6. J. P. Mangion, S. Mancini, C. Bachy, A. de Weggheleire, F. Zamatto, “Diphtheria in Europe,” Public Health Action, vol. 13, no. 2, pp. 31 – 33, Jun. 2023.
   DOI: 10.5588/pha.23.0011
   PMid: 37359068
   PMCid: PMC10290257
7. M. Prygiel et al., “Challenges of Diphtheria Toxin Detection,” Toxins, vol. 16, no. 6, 245, May 2024.
   DOI: 10.3390/toxins16060245
   PMid: 38922140
   PMCid: PMC11209151
8. S. A. Truelove et al., “Clinical and Epidemiological Aspects of Diphtheria: A Systematic Review and Pooled Analysis,” Clin. Infect. Dis., vol. 71, no. 1, pp. 89 – 97, Jun. 2020.
   DOI: 10.1093/cid/ciz808
   PMid: 31425581
   PMCid: PMC7312233
9. L. F. Hewitt, “Use of antibiotics in the treatment of experimental diphtheria infections,” Br. J. Exp. Pathol., vol. 31, no. 5, pp. 597 – 602, Oct. 1950.
   PMid: 14791911
   PMCid: PMC2073362
10. A. J. Leidner et al., “Cost-effectiveness of adult vaccinations: A systematic review,” Vaccine, vol. 37, no. 2, pp. 226 – 234, Jan. 2019.
    DOI: 10.1016/j.vaccine.2018.11.056
    PMid: 30527660
    PMCid: PMC6545890
11. Izveštaji o sprovedenoj imunizaciji na teritoriji Republike Srbije u 2014. godini, Institut za javno zdravlje Srbije “Dr Milan Jovanović Batut”, Beograd, Srbija, 2015.
    (Reports on immunization carried out on the territory of the Republic of Serbia in 2014, Institute for Public Health of Serbia “Dr Milan Jovanović Batut”, Belgrade, Serbia, 2015.)
    Retrieved from: https://www.batut.org.rs/index.php?category%20id=140
    Retrieved on: Jan. 20, 2024
12. Izveštaji o sprovedenoj imunizaciji na teritoriji Republike Srbije u 2016. godini, Institut za javno zdravlje Srbije “Dr Milan Jovanović Batut”, Beograd, Srbija, 2017.
    (Reports on immunization carried out on the territory of the Republic of Serbia in 2016, Institute for Public Health of Serbia “Dr Milan Jovanović Batut”, Belgrade, Serbia, 2017.)
    Retrieved from: https://www.batut.org.rs/index.php?category%20id=140
    Retrieved on: Jan. 20, 2024
13. Izveštaji o sprovedenoj imunizaciji na teritoriji Republike Srbije u 2017. godini, Institut za javno zdravlje Srbije “Dr Milan Jovanović Batut”, Beograd, Srbija, 2018.
    (Reports on immunization carried out on the territory of the Republic of Serbia in 2017, Institute for Public Health of Serbia “Dr Milan Jovanović Batut”, Belgrade, Serbia, 2018.)
    Retrieved from: https://www.batut.org.rs/index.php?category%20id=140
    Retrieved on: Jan. 20, 2024
14. Izveštaji o sprovedenoj imunizaciji na teritoriji Republike Srbije u 2022. godini, Institut za javno zdravlje Srbije “Dr Milan Jovanović Batut”, Beograd, Srbija, 2023.
    (Reports on immunization carried out on the territory of the Republic of Serbia in 2022, Institute for Public Health of Serbia “Dr Milan Jovanović Batut”, Belgrade, Serbia, 2023.)
    Retrieved from: https://www.batut.org.rs/index.php?category%20id=140
    Retrieved on: Jan. 20, 2024
15. Izveštaji o sprovedenoj imunizaciji na teritoriji Republike Srbije u 2018. godini, Institut za javno zdravlje Srbije “Dr Milan Jovanović Batut”, Beograd, Srbija, 2019.
    (Reports on immunization carried out on the territory of the Republic of Serbia in 2018, Institute for Public Health of Serbia “Dr Milan Jovanović Batut”, Belgrade, Serbia, 2019.)
    Retrieved from: https://www.batut.org.rs/index.php?category%20id=140
    Retrieved on: Jan. 20, 2024
16. S. M. Aljunid et al., “Economic impact of switching from partially combined vaccine ‘Pentaxim® and hepatitis B’ to fully combined vaccine ‘Hexaxim®’ in the Malaysian National Immunization Program,” BMC Health Serv. Res., vol. 22, no. 1, 34, Jan. 2022.
    DOI: 10.1186/s12913-021-07428-7
    PMid: 34986870
    PMCid: PMC8734051
17. I. Rengganis, “Adult Diphtheria Vaccination,” Acta Med. Indones., vol. 50, no. 3, pp. 268 – 272, Jul. 2018.
    PMid: 30333279
18. Z. Radovanović, Istina o vakcinama: Priručnik za savesne roditelje, 2. dopunjeno i prošireno izdanje, Smederevo, Srbija: Heliks, 2017.
    (Z. Radovanović, The truth about vaccines: Manual for conscientious parents,2nd amended and expanded ed., Smederevo, Serbia: Helix, 2017.)
19. M. Prygiel, E. Mosiej, P. Górska, A. A. Zasada, “Diphtheria-tetanus-pertussis vaccine: past, current & future,” Future Microbiol., vol. 17, no. 3, pp. 185 – 197, Feb. 2022.
    DOI: 10.2217/fmb-2021-0167
    PMid: 34856810
20. K. Yang, H. Kim, E. Ortiz, C. Huoi, J. Kang, “Post-Marketing Safety Surveillance of a Childhood Pentavalent Diphtheria-Tetanus-Acellular Pertussis-Polio and Haemophilus influenzae Type B (DTaP-IPV//Hib) Vaccine in South Korea,” Infect. Dis. Ther., vol. 12, no. 2, pp. 499 – 511, Feb. 2023.
    DOI: 10.1007/s40121-022-00724-7
    PMid: 36520326
    PMCid: PMC9925623
21. R. Petrović, Imunizacije, Beograd, Srbija: Velarta, 1996.
    (R. Petrović, Immunizations, Belgrade, Serbia: Velarta, 1996.)
22. F. Kahn, T. Lepp, J. Storsaeter, “Primary diphtheria immunization of adolescents and adults with low-dose vaccine, a survey of historic evidence from the literature,” Acta Paediatr., vol. 112, no. 2, pp. 242 – 245, Feb. 2023.
    DOI: 10.1111/apa.16589
    PMid: 36333877
    PMCid: PMC10099547
23. Z. Garib, M. C. Danovaro-Holliday, Y. Tavarez, I. Leal, C. Pedreira, “Diphtheria in the Dominican Republic: reduction of cases following a large outbreak,” Rev. Panam. Salud Publica, vol. 38, no. 4, pp. 292 – 229, Oct. 2015.
    PMid: 26758220
24. L. W. Rümke, H. C. Rümke, “Diphtheria: a ‘forgotten’ disease?,” Ned. Tijdschr. Geneeskd., vol. 163, no. 42, D4036, Oct. 2019.
    PMid: 31609562
25. G. Kaur et al., “Routine Vaccination Coverage - Worldwide, 2022,” MMWR Morb. Mortal. Wkly Rep., vol. 72, no. 43, pp. 1155 – 1161, Oct. 2023.
    DOI: 10.15585/mmwr.mm7243a1
    PMid: 37883326
    PMCid: PMC10602616
26. Q. Hasan, Y. F. Hutin, R. Hajjeh, “Immunization in the Eastern Mediterranean Region: some signs of post-COVID-19 recovery, but more work ahead,” East. Mediterr. Health J., vol. 29, no. 9, pp. 681 – 683, Sep. 2023.
    DOI: 10.26719/2023.29.9.681
    PMid: 37776128
27. V. Petrović, Imunizacija protiv zaraznih bolesti, Novi Sad, Srbija: Medicinski fakultet, 2015.
    (V. Petrović, Immunization against infectious diseases, Novi Sad, Serbia: Faculty of Medicine, 2015.)
    Retrieved from: https://izjzv.org.rs/uploads/52458a10-bf00-7942-ce12-/Imunizacija_protiv_zaraznih_bolesti.pdf
    Retrieved on: Jan. 20, 2024
28. V. Turkulov i sar., Infektivne bolesti za studente medicine,2. izdanje, Novi Sad, Srbija: Medicinski fakultet, 2015.
    (V. Turkulov et al., Infectious diseases for medical students,2nd ed., Novi Sad, Serbia: Faculty of Medicine, 2015.)
29. Clinical management of diphtheria: guideline, WHO/DIPH/Clinical/2024.1, WHO, Geneva, Switzerland, 2024.
    Retrieved from: https://iris.who.int/bitstream/handle/10665/375887/WHO-DIPH-Clinical-2024.1-eng.pdf?sequence=1
    Retrieved on: Feb. 20, 2024
30. E. Sifuentes-Rodríguez, D. Palacios-Reyes, “COVID-19: The outbreak caused by a new coronavirus,” Bol. Med. Hosp. Infant. Mex., vol. 77, no. 2, pp. 47 – 53, 2020.
    DOI: 10.24875/BMHIM.20000039
    PMid: 32226003
31. A. A. Al-Dar et al., “Diphtheria resurgence in Sada’a-Yemen, 2017-2020,” BMC Infect. Dis., vol. 22, no. 1, 46, Jan. 2022.
    DOI: 10.1186/s12879-022-07033-x
    PMid: 35016630
    PMCid: PMC8751122