Browsing by Author "Cohen, Cheryl"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Effectiveness of the 13-valent pneumococcal conjugate vaccine against invasive pneumococcal disease in South African children : a case-control study
    (Elsevier, 2017-01-27) Cohen, Cheryl; Von Mollendorf, Claire; De Gouveia, Linda; Lengana, Sarona; Meiring, Susan; Quan, Vanessa; Nguweneza, Arthermon; Moore, David P.; Reubenson, Gary; Moshe, Mamokgethi; Madhi, Shabir A.; Eley, Brian; Hallbauer, Ute; Finlayson, Heather; Varughese, Sheeba; O'Brien, Katherine L.; Zell, Elizabeth R.; Klugman, Keith P.; Whitney, Cynthia G.; Von Gottberg, Anne
    Background: The 13-valent pneumococcal conjugate vaccine (PCV13) was designed to include disease-causing serotypes that are important in low-income and middle-income countries. Vaccine eff ectiveness estimates are scarce in these settings. South Africa replaced PCV7 with PCV13 in 2011 using a 2 + 1 schedule. We aimed to assess the eff ectiveness of two or more doses of PCV13 against invasive pneumococcal disease in children with HIV infection and in those not infected with HIV. Methods: Cases of invasive pneumococcal disease in children aged 5 years or younger were identifi ed through national laboratory-based surveillance. Isolates were serotyped with the Quellung reaction or PCR. We sought in-hospital controls for every case, matched for age, HIV status, and study site. We aimed to enrol four controls for every case not infected with HIV and six controls for every case with HIV infection (case-control sets). With conditional logistic regression, we calculated vaccine eff ectiveness as a percentage, with the equation 1 – [adjusted odds ratio for vaccination] × 100. We included data from an earlier investigation of PCV7 to assess vaccine eff ectiveness in children exposed to but not infected with HIV and in malnourished children not infected with HIV. Findings: Between January, 2012, and December, 2014, we enrolled children aged 16 weeks or older to our study: 240 were cases not infected with HIV, 75 were cases with HIV infection, 1118 were controls not infected with HIV, and 283 were controls with HIV infection. The eff ectiveness of two or more doses of PCV13 against PCV13-serotype invasive pneumococcal disease was 85% (95% CI 37 to 96) among 11 case-control sets of children not infected with HIV and 91% (–35 to 100) among three case-control sets of children with HIV infection. PCV13 eff ectiveness among 26 case-control sets of children not infected with HIV was 52% (95% CI –12 to 79) against all-serotype invasive pneumococcal disease and 94% (44 to 100) for serotype 19A. Vaccine eff ectiveness against PCV7-serotype invasive pneumococcal disease was 87% (95% CI 38 to 97) in children exposed to HIV but uninfected and 90% (53 to 98) in malnourished children not infected with HIV. Interpretation: Our results indicate that PCV13 in a 2 + 1 schedule is eff ective for preventing vaccine-type pneumococcal infections in young children not infected with HIV, including those who are malnourished or who have been exposed to HIV. Although the point estimate for PCV13 vaccine eff ectiveness in children infected with HIV was high, it did not reach signifi cance, possibly because of the small sample size. These fi ndings support recommendations for widespread use of pneumococcal conjugate vaccine in low-income and middle-income countries.
  • Thumbnail Image
    Item
    Hepatitis B sero-prevalence in children under 15 years of age in South Africa using residual samples from community-based febrile rash surveillance
    (Public Library of Science, 2019-05-31) Prabdial-Sing, Nishi; Makhathini, Lillian; Smit, Sheilagh Brigitte; Manamela, Morubula Jack; Motaze, Nkengafac Villyen; Cohen, Cheryl; Suchard, Melinda Shelley
    Introduction and methods: Hepatitis B is a vaccine preventable disease and is notifiable in South Africa. Hepatitis B vaccination was incorporated into the Expanded Programme on Immunisation in South Africa in 1995. We used a convenience sample from community-based febrile rash surveillance in 2013 to estimate hepatitis B sero-prevalence. Of samples serologically negative for acute measles infection, 450 samples spanning nine provinces of South Africa were tested for hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs) and hepatitis B core antibody (anti-HBc). Results: Two children (2/450; 0.4%) tested positive for HBsAg. Three hundred and three children (67.3%) had evidence of vaccine induced immunity. Vaccine induced immunity was present in 80.2% of 1–5 year olds, but only 60.3% of 10–14 year olds. Natural immunity, indicating exposure to circulating hepatitis B, was present in 13/450 (2.9%) children. Conclusion: Chronic hepatitis B in South African has decreased in prevalence from highly endemic levels prior to vaccine introduction to approximately 0.4% in this sample, demonstrating impact of a successful vaccination programme 18 years after introduction. Decreased vaccine-induced immunity with increasing age may reflect waning antibody titres over time.
  • Thumbnail Image
    Item
    HIV infection and the epidemiology of Invasive Pneumococcal Disease (IPD) in South African adults and older children prior to the introduction of a Pneumococcal Conjugate Vaccine (PCV)
    (Public Library of Science, 2016) Meiring, Susan; Cohen, Cheryl; Quan, Vanessa; De Gouveia, Linda; Feldman, Charles; Karstaedt, Alan; Klugman, Keith P.; Madhi, Shabir A.; Rabie, Helene; Sriruttan, Charlotte; Von Gottberg, Anne; GERMS-SA
    Introduction: Streptococcus pneumoniae is the commonest cause of bacteremic pneumonia among HIV-infected persons. As more countries with high HIV prevalence are implementing infant pneumococcal conjugate vaccine (PCV) programs, we aimed to describe the baseline clinical characteristics of adult invasive pneumococcal disease (IPD) in the pre-PCV era in South Africa in order to interpret potential indirect effects following vaccine use. Methods: National, active, laboratory-based surveillance for IPD was conducted in South Africa from 1 January 2003 through 31 December 2008. At 25 enhanced surveillance (ES) hospital sites, clinical data, including HIV serostatus, were collected from IPD patients ≥ 5 years of age. We compared the clinical characteristics of individuals with IPD in those HIV-infected and -uninfected using multivariable analysis. PCV was introduced into the routine South African Expanded Program on Immunization (EPI) in 2009. Results: In South Africa, from 2003–2008, 17 604 cases of IPD occurred amongst persons ≥ 5 years of age, with an average incidence of 7 cases per 100 000 person-years. Against a national HIV-prevalence of 18%, 89% (4190/4734) of IPD patients from ES sites were HIV-infected. IPD incidence in HIV-infected individuals is 43 times higher than in HIV-uninfected persons (52 per 100 000 vs. 1.2 per 100 000), with a peak in the HIV-infected elderly population of 237 per 100 000 persons. Most HIV-infected individuals presented with bacteremia (74%, 3 091/4 190). HIV-uninfected individuals were older; and had more chronic conditions (excluding HIV) than HIV-infected persons (39% (210/544) vs. 19% (790/4190), p<0.001). During the pre-PCV immunization era in South Africa, 71% of serotypes amongst HIV-infected persons were covered by PCV13 vs. 73% amongst HIV-uninfected persons, p = 0.4, OR 0.9 (CI 0.7–1.1). Conclusion: Seventy to eighty-five percent of adult IPD in the pre-PCV era were vaccine serotypes and 93% of cases had recognized risk factors (including HIV-infection) for pneumococcal vaccination. These data describe the epidemiology of IPD amongst HIV-infected and -uninfected adults during the pre-PCV era and provide a robust baseline to calculate the indirect effect of PCV in future studies.