Re-emergence of Diphtheria after COVID-19 pandemic in Pakistan: Time to consider booster vaccination strategies
Authors: Muhammad Salman, Muhammad S. Rana, Muhammad Usman, Muhammad Tahir, Kashif Muqarrab, Muhammad B. Alam, Massab Umair, Muhammad Anas, Nadeem Ullah, Ayesha Farooq, Zurva Ashraf
Journal: Journal of Infection (2024)

Dear Editor, I would like to draw attention to the recent article entitled" China Faces the Challenge of Influenza A virus, Including H3N8, in the post-COVID-19 era, by Tao Ren and colleagues1Cai J. Ruan J. Lin Q. et al.China faces the challenge of influenza A virus, including H3N8, in the post-COVID-19 era.Journal of Infection. 2023; Abstract Full Text Full Text PDF Scopus (0) Google Scholar published in this journal. The authors discussed the outbreak of Influenza virus in China following the COVID-19 pandemic. In this context, we wish to report the re-emergence of Diphtheria in Pakistan after the COVID-19 pandemic. Diphtheria, caused by the toxin-producing bacteria, Corynebacterium diphtheriae is a rare yet severe and fatal infectious disease. The bacterium usually infects the throat and nose, it can also lead to skin infections. The bacteria's ability to produce harmful toxins poses life-threatening complications, including heart issues such as myocarditis, neuritis, paralysis, and renal failure. Diphtheria is transmitted from person to person, usually through respiratory droplets, coughing, and sneezing2Diphtheria. 2023 [cited 2024 20 Feb 2024]; Available from: 〈https://www.who.int/news-room/fact-sheets/detail/diphtheria〉.Google Scholar. Before the widespread use of the diphtheria vaccine in 1930, global diphtheria cases and outbreaks were prevalent. From 2000-2022, a total of 190,954, Diphtheria cases were reported to the World Health Organization from all WHO regions3Diphtheria reported cases and incidence. [cited 2024 20 Feb 2024]; Available from: 〈https://immunizationdata.who.int/pages/incidence/DIPHTHERIA.html?CODE=Global&YEAR=〉.Google Scholar. This report highlights the re-emergence of Diphtheria in Pakistan after the COVID-19 pandemic. In Pakistan, Diphtheria is a notifiable disease for which the case investigation and reporting is mandatory for all public and private hospitals. Pakistan had sporadic transmission of Diphtheria since 2000 and the first outbreak of Diphtheria was documented in 2013. Localized Diphtheria outbreaks in Pakistan were also documented from 2017-2022. After the COVID-19 pandemic, the Diphtheria outbreak surpassed all previous records. According to the Ministry of National Health Services, Regulations and Coordination, from 1 January to 27 December 2023, a total of 996 Diphtheria cases (912 suspected and 84 labs confirmed) resulting in 124 deaths were recorded from all provinces of Pakistan, mostly in Khyber Pakhtunkhwa (58%), Sindh (24.4%), Punjab (14.5%), Balochistan (2.2), Islamabad (0.3%), and Azad Jammu& Kashmir (0.3%). District-wise distribution of Diphtheria cases is shown in Fig. 1. Among the reported Diphtheria cases,53% occurred among male and 47% among female individuals. By age group, 25% of cases were reported in children less than five years of age, and 75% of cases were reported in patients more than five years of age. Only about 36% of reported cases were vaccinated. Epidemiological trends of Diphtheria cases and DPT3 vaccination coverage in Pakistan between 2000-20234Diphtheria reported cases and incidence. 20 Feb 2024 ]; Available from: 〈https://immunizationdata.who.int/pages/incidence/diphtheria.html?CODE=EMR+PAK&YEAR=〉.Google Scholar, 5Immunization, DPT (% of children ages 12-23 months) - Pakistan. 20 Feb 2024 ]; Available from: 〈https://data.worldbank.org/indicator/SH.IMM.IDPT?locations=PK〉.Google Scholar are presented in Fig. 2. These findings, such as 64% of cases being unvaccinated, underscore the urgent need to improve routine immunization coverage, particularly considering that 75% of cases were in individuals over five years old, emphasizing the necessity for booster vaccination strategies. It's essential to note that the actual number of cases may be higher due to underreporting in several WHO regions, including Pakistan. For the prevention and control of vaccine-preventable diseases (VPDs), the Expanded Programme on Immunization (EPI) was established in Pakistan in 1978. The pentavalent vaccine is included as a part of routine immunization in Pakistan, which protects against Haemophilus influenza B, diphtheria, pertussis, tetanus, and hepatitis B. In Pakistan, children receive the pentavalent vaccine at 6, 10, and 14 weeks of age. Within Pakistan, estimates of vaccination coverage with the pentavalent vaccine (DPT3), in 2023 were reported to be 85%6Shahid S. Ahmed S. Qazi M.F. et al.Differential coverage for vaccines in the expanded program on immunization (EPI) among children in rural Pakistan.Vaccine. 2023; 41: 2680-2689Crossref Scopus (1) Google Scholar. The actual 85% coverage of DPT is good enough for community protection but the ground reality of this reported coverage may be much different according to the current findings. According to WHO, the risk of diphtheria is considered high if the coverage of DPT in children less than 1 year is below 50% and the risk of infection and outbreak is low if the actual coverage is above 79%7Blumberg L. Prieto M.A. Diaz J.V. et al.The preventable tragedy of diphtheria in the 21st century.International Journal of Infectious Diseases. 2018; 71: 122-123Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar. The global Vaccine Action Plan 2011-2020 endorsed by the World Health Assembly in 2012, recommends that each country should reach DPT-3 coverage of 90% in their routine immunization schedule by 20208Sharma N.C. Efstratiou A. Mokrousov I. et al.Diphtheria.Nature Reviews Disease Primers. 2019; 5: 1-18Crossref Scopus (98) Google Scholar. Pakistan's immunization indicators remain below the expected benchmarks, with challenges in achieving goals related to polio eradication, and measles-rubella elimination. Pakistan is third among the countries with the most unvaccinated and under-vaccinated children. Of the 3.8 million infants who did not receive their third dose of the DTP3 vaccine in the Region in 2015, 40% of those were living in Pakistan9Pakistan: Expanded Programme on Immunization. 20 Feb 2024 ]; Available from: 〈https://www.emro.who.int/pak/programmes/expanded-programme-on-immunization.html〉.Google Scholar. Vaccine coverage serves as an indicator of the performance of immunization programs and progress toward public health goals. Pakistan has not yet met the WHO's target of a >95% vaccination rate. Additionally, vaccine coverage rates in Pakistan exhibit significant variation between provinces. There are wide variations within the province for immunization coverage in urban and rural areas. Diphtheria was a major cause of childhood morbidity and mortality during the pre-vaccine era. The resurgence of Diphtheria exacerbated by the COVID-19 pandemic's impact on vaccination programs, necessitates immediate action. With a case fatality rate of 5-17% among the unvaccinated population, diphtheria poses a serious public health threat in Pakistan. Accurate diagnosis and proper case management by using diphtheria antitoxin (DAT) or recommended antibiotics is important to save lives. However, diphtheria is a continuously evolving pathogen, to becomes resistant to a wide variety of antibiotics. Case-based surveillance, early outbreak detection, and suitable preventive measures, including vaccination, are crucial. Urgent steps must be taken to enhance routine immunization coverage, implement booster vaccination strategies for addressing the problem of waning immunity, and ensure accurate and reliable data collection on diphtheria cases for effective public health interventions. All authors declared that there is no conflict of interest related to this article.