Killed oral cholera vaccines (OCVs) are part of the standard response package to a cholera outbreak, although the two-dose regimen of vaccines that has been prequalified by the World Health Organization (WHO) poses challenges to timely and efficient reactive vaccination campaigns.¹ Recent data suggest that the first dose alone provides short-term protection, similar to that of two doses, which may largely dictate the effect of OCVs during epidemics.^2-4

Background. Monovalent rotavirus vaccine was introduced in the routine public health immunization program in Lusaka, Zambia, in January 2012 and was rolled out countrywide in November 2013. We examined the effect of rotavirus vaccination on hospitalization for all-cause acute gastroenteritis (AGE) and rotavirus-specific AGE at a large referral hospital in Lusaka.

Introduction: Zambia experienced a major cholera outbreak in 2017–2018, with more than 5905 cases reported countrywide, predominantly from the peri-urban slums of Lusaka city. The WHO recommends the use of oral cholera vaccines (OCVs) together with traditional control measures, including health promotion, provision of safe water and improving sanitation, in cholera endemic areas and during cholera outbreaks. In response to this outbreak, the Zambian government implemented the OVC campaign and administered the Euvichol-plus vaccine in the high-risk subdistricts of Lusaka. Although OCVs have been shown to be effective in preventing cholera infection in cholera endemic and outbreak settings, the effectiveness of the Euvichol-plus vaccine has not yet been evaluated in Zambia. This study aimed to determine the effectiveness of two doses of OCV administered during the 2017/2018 vaccination campaign. Methods: We conducted a matched case–control study involving 79 cases and 316 controls following the mass vaccination campaign in the four subdistricts of Lusaka (Chawama, Chipata, Kanyama and Matero). Matching of controls was based on the place of residence, age and sex. Conditional logistic regression was used for analysis. Adjusted OR (AOR), 95% CI and vaccine effectiveness (1-AOR) for two doses of Euvichol-plus vaccine and any dose were estimated (p < 0.05). Results: The AOR vaccine effectiveness for two doses of Euvichol-plus OCV was 81.0% (95% CI 66.0% to 78.0%; p<0.01). Secondary analysis showed that vaccine effectiveness for any dose was 74.0% (95% CI 50.0% to 86.0%; p<0.01). Conclusion: These findings show that two doses of Euvichol-plus OCV are effective in a cholera outbreak setting in Lusaka, Zambia. The findings also indicate that two doses are more effective than a single dose and thus support the use of two doses of the vaccine as part of an integrated intervention to cholera control during outbreaks.

Background: Intussusception, a rare adverse event associated with rotavirus vaccines in some settings, is a common cause of intestinal obstruction in infants and toddlers globally with a peak age of 4–6 months. This age group may overlap with the extended age of administering rotavirus vaccine. Methods: A retrospective (January 2007 to June 2009) and prospective (July 2009 to June 2012) survey was conducted in 9 Zambian hospitals. Children between 0 and 24 months who were operated on for intestinal obstruction/intussusception were identified in theatre log books. In the latter part of the survey, patients were recruited prospectively. Demographic, clinical and surgical data from hospital files were collected for each patient. Results: One-hundred and five children were identified to have undergone surgery for intussusceptions. Many were boys 57.6% (57/99). Of those with complete data, intussusception was common in infants 86.9% (86/99) and many children (68.0%) were between 3 and 8 months of age with a peak age of 5–6 months. Lusaka had the highest number of children with intussusception with an estimated annual incidence rate of 12/100,000 in children <2 years of age. The overall case fatality rate was very high 33.7% (31/92). Conclusion: Intussusception was common in infants with a peak age of 5–6 months, and of particular concern is the group of 2–4 months the age of rotavirus vaccination. The estimated incidence rate of 12/100,000 is an underestimate as many cases may not present for care. The high case fatality rate of 33.7% is due to both delayed presentation and diagnosis in hospital.

Background: Pneumococcus is a leading cause of pneumonia and meningitis. Zambia introduced a 10-valent pneumococcal conjugate vaccine (PCV10) in July 2013 using a 3-dose primary series at ages 6, 10, and 14 weeks with no booster. We evaluated the impact of PCV10 on meningitis and pneumonia hospitalizations. Methods: Using hospitalization data from first-level care hospitals, available at the Ministry of Health, and from the largest pediatric referral hospital in Lusaka, we identified children aged <5 years who were hospitalized with pneumonia or meningitis from January 2010–December 2016. We used time-series analyses to measure the effect of PCV10 on monthly case counts by outcome and age group (<1 year, 1–4 years), accounting for seasonality. We defined the pre- and post-PCV10 periods as January 2010–June 2013 and July 2014–December 2016, respectively. Results: At first-level care hospitals, pneumonia and meningitis hospitalizations among children aged <5 years accounted for 108 884 and 1742 admissions in the 42 months pre-PCV10, respectively, and 44 715 and 646 admissions in the 30 months post-PCV10, respectively. Pneumonia hospitalizations declined by 37.8% (95% confidence interval [CI] 21.4–50.3%) and 28.8% (95% CI 17.7–38.7%) among children aged <1 year and 1–4 years, respectively, while meningitis hospitalizations declined by 72.1% (95% CI 63.2–79.0%) and 61.6% (95% CI 50.4–70.8%), respectively, in these age groups. In contrast, at the referral hospital, pneumonia hospitalizations remained stable and a smaller but significant decline in meningitis was observed among children aged 1–4 years (39.3%, 95% CI 16.2–57.5%). Conclusions: PCV10 introduction was associated with declines in meningitis and pneumonia hospitalizations in Zambia, especially in first-level care hospitals.