Risk factors for pneumococcal carriage in adults living with HIV on antiretroviral therapy in the infant pneumococcal vaccine era in Malawi

Abstract

Objective: Adults living with HIV (ALWHIV) on antiretroviral therapy (ART) are at high risk of pneumococcal carriage and disease. To help evaluate carriage risk in African ALWHIV at least 4 years after infant pneumococcal conjugate vaccination introduction in 2011, we assessed association between pneumococcal carriage and potential risk factors.Methods: Nasopharyngeal swabs were collected from adults aged 18-40 years attending an ART clinic during rolling, cross-sectional surveys in Blantyre, Malawi between 2015 and 2019. We fitted generalized additive models to estimate the risk of sex, social economic status (SES), living with a child less than 5 years, and ART duration on carriage.Results: Of 2067 adults, median age was 33 years (range 28-37), 1427 (69.0%) were women, 1087 (61.4%) were in low-middle socioeconomic-status (SES), 910 (44.0%) were living with a child less than 5 years, and median ART duration was 3 years (range 0.004-17). We estimated 38.2 and 60.6% reductions in overall and vaccine-serotype carriage prevalence. Overall carriage was associated with low SES, living with a child less than 5 years and shorter duration on ART. By contrast, vaccine-type carriage was associated with living without a child less than 5 years and male sex. Conclusion:Despite temporal reductions in overall and vaccine-serotype carriage, there is evidence of incomplete vaccine-serotype indirect protection. A targeted-vaccination campaign should be considered for ALWHIV, along with other public health measures to further reduce vaccine-serotype carriage and therefore disease.

Frequent shedding of multi-drug resistant pneumococci among adults living with HIV on suppressive antiretroviral therapy in Malawi

“…PLHIV, compared to HIV-uninfected participants were older, with 44% (24/55) and 20% (7/35) >36 years old, respectively (p=0.049). Likewise, compared to HIV-uninfected participants, PLHIV had a lower socioeconomic status as measured by asset ownership index 12 (median 4 [IQR 2.0-5.0] vs. 6 [3.5-7.50], p=0.005), and a lower CD4 count (median 514 cells/μl [IQR 652-927] vs. 760 cells/μl [IQR [332-750], p<0.001) (Table 1).…”

“…Likewise, compared to HIV-uninfected participants, PLHIV had a lower socioeconomic status as measured by asset ownership index 12 59% [53.7-64.8] p<0.001) (Fig. 2a).…”

“…Moreover, pneumococcal carriage prevalence has been reported to be over two-fold higher in PLHIV on antiretroviral therapy (ART) (40-60%) than in those HIV-uninfected (8-15%) or ART-naïve PLHIV (18-25%) 10, 11 . Residual carriage of all PCV13 serotypes (VTs) among Malawian adults living with HIV on ART has remained relatively high 7, 11 , with low socioeconomic status having been shown to exacerbate overall carriage prevalence 12 .…”

Estimating pneumococcal carriage dynamics in adults living with HIV in a mature infant pneumococcal conjugate vaccine program in Malawi, a modelling study

“…In a multivariate longitudinal analysis, pneumococcal carriage acquisition was higher in females than males (NVT [Hazard Ratio [HR]: 1.53, Introduction Streptococcus pneumoniae (pneumococcus) commonly colonises the nasopharynx (NP) of children and adults [1]. Pneumococcal colonisation precedes disease, such as pneumonia, meningitis, and bacteraemia [1][2][3], and is also prerequisite for transmission [1]. The pneumococcus causes excessively high pneumococcal carriage and disease burden in adults living with human immunodeficiency virus (ALWHIV) on antiretroviral therapy (ART) compared to adults without HIV (HIV-) [4,5], despite the substantial coverage of ART and suppression of viral load [6,7].…”

“…Since female adults are more likely to interact with younger children due to cultural and parental roles, social mixing is highly intensive between children and females compared to male adults in this setting [31], likely resulting in higher carriage acquisition risk in females than males consistent with our findings in this study. Furthermore, household spread of pneumococcus is usually influenced by higher household density [26, 32, 33], and having more younger children in the house who are a major reservoir of pneumococcal carriage transmission increases the risk of pneumococcal carriage acquisition [3]. Similarly, higher pneumococcal carriage acquisitions in low than high SES households, as shown here and in previous studies in this setting [3], is likely related to poor living conditions, including poor ventilation and overcrowding.…”