BCG vaccination and tuberculosis prevention: A forty years cohort study, Monastir, Tunisia

Abstract

We aimed to describe incidence, trends of tuberculosis (TB) over 18 years and to evaluate the impact of the BCG vaccine after four decades of immunization program according to three protocols. We performed a cohort study including declared cases in Monastir from January 1, 2000 to December 31, 2017. We reported 997 cases of TB. The predominant site was pulmonarylocalization (n = 486). The age standardized incidence of pulmonary and lymph node TB per 100,000 inh were 5.71 and 2.57 respectively. Trends were negative for pulmonary TB (PTB) (b = - 0.82; r = -0.67; p<10 −3 ) and positive for lymph node localization (b = 1.31; r = 0.63; p<10 −3 ). We had not notified cases of HIV associated with TB. Crude incidence rate (CIR) of PTB per 100,000 inh was 8.17 in Non-Vaccinated Cohort (NVC) and 2.85 in Vaccinated Cohort (VC) (p < 0.0001). Relative risk reduction (RRR) of BCG vaccination was 65.1% (95%CI:57.5;71.4) for pulmonary localization and 65% (95%CI:55; 73) for other localizations. We have not established a significant RRR of BCG vaccination on lymph node TB. Protocol 3 (at birth) had the highest effectiveness with a RRR of 96.7% (95%CI: 86.6%; 99.2%) and 86% (95%CI:71%;91%) in patients with PTB and other localizations TB respectively. In Cox regression model the HR was 0.061 (95% CI 0.015–0.247) for PTB and 0.395 (95% CI 0.185–0.844) for other localizations TB in patients receiving protocol 3 compared to NVC. For lymph-node TB, HR was 1.390 (95% CI 1.043–1.851) for protocol 1 and 1.849 (95% CI 1.232–2.774) for protocol 2 compared to NVC. Depending on the three protocols, the BCG vaccine had a positive impact on PTB and other TB localizations that must be kept and improved. However, protocols 1 and 2 had a reverse effect on lymph node TB.

The Spectrum of Bacille Calmette–Guérin Diseases in Children—A Decade of Data from Neonatal Vaccination Settings

“…Some countries, especially those with low TB incidence, have delayed BCG administration until 3 and 6 months to avoid BCG complications in infants born with immunodeficiency, and others went to selective vaccination for high-risk infants instead of taking a universal approach [ 10 , 11 , 30 ]. The experience from Greenland, Tunisia, and Bahrain of increased incidence and/or severity of TB especially in children after waving out universal neonatal BCG vaccine is a call for careful consideration before adopting such an approach even by low incident countries [ 30 , 31 , 32 ]. The rate of all TB forms in Oman decreased from 21.4 per 100,000 population in 1991 to 5.9 per 100,000 population in 2018, remaining remained constant since then.…”

Tuberculosis epidemiological trend in Sousse, Tunisia during twenty years (2000–2019)

“…In Sousse, Tunisia, the tuberculosis incidence increasing trend can also be explained by the above-described factors, as the population is aging [ 28 ], and there is a quite high prevalence of smoking and diabetes [ 17 , 29–31 ]. Other studies done in Tunisia, have also have objectified this rise in incidence whether in the South of Tunisia [ 7 ] and Monastir governorate [ 32 ].…”