Pneumococcal population genomics changes during the early time period of conjugate vaccine uptake in southern India.

Streptococcus pneumoniae is a major cause of invasive disease of young children in low- and middle-income countries. In southern India, pneumococcal conjugate vaccines (PCVs) that can prevent invasive pneumococcal disease began to be used more frequently after 2015. To characterize pneumococcal evolution during the early time period of PCV uptake in southern India, genomes were sequenced and selected characteristics were determined for 402 invasive isolates collected from children <5 years of age during routine surveillance from 1991 to 2020. Overall, the prevalence and diversity of vaccine type (VT) and non-vaccine type (NVT) isolates did not significantly change post-uptake of PCV. Individually, serotype 1 and global pneumococcal sequence cluster (GPSC or strain lineage) 2 significantly decreased, whereas serotypes 6B, 9V and 19A and GPSCs 1, 6, 10 and 23 significantly increased in proportion post-uptake of PCV. Resistance determinants to penicillin, erythromycin, co-trimoxazole, fluoroquinolones and tetracycline, and multidrug resistance significantly increased in proportion post-uptake of PCV and especially among VT isolates. Co-trimoxazole resistance determinants were common pre- and post-uptake of PCV (85 and 93 %, respectively) and experienced the highest rates of recombination in the genome. Accessory gene frequencies were seen to be changing by small amounts across the frequency spectrum specifically among VT isolates, with the largest changes linked to antimicrobial resistance determinants. In summary, these results indicate that as of 2020 this pneumococcal population was not yet approaching a PCV-induced equilibrium and they highlight changes related to antimicrobial resistance. Augmenting PCV coverage and prudent use of antimicrobials are needed to counter invasive pneumococcal disease in this region.

Impact of exclusive breast feeding until six months of age on common illnesses: A prospective observational study.

Objectives: The WHO recommends exclusive breast feeding (EBF) for all infants for the first six months of life. National Family Health Survey-4 (2015-16) shows EBF rates of only 54.9%. We conducted a prospective study to assess prevalence of EBF and incidences of illnesses in infants from birth till six months of age. Methods: Healthy term infants born in our hospital between December 2017 and November 2018 were recruited at birth. Structured diary cards were given to mothers to record feeding patterns, occurrence and severity of illnesses. Mothers were interviewed at 6, 10, 14 and 26 weeks or contacted by telephone at 18 and 22 weeks. Data were analyzed using SPSS IBM Statistics 22. Results: The prevalence of EBF among 450 infants (M:F = 1.3:1) who completed the study was 47% at 6 months. 185 (69 EBF + 116 non-EBF) of 450 infants reported a total of 242 illnesses, most commonly respiratory (82.6%) followed by gastrointestinal (11.6%). Number of illnesses per infant was 0.45 and 0.6 in EBF group and non-EBF group respectively (p = 0.015). Illness incidences in EBF infants were significantly lower during all successive time intervals after 10 weeks of age. Logistic regression analysis confirmed significantly lower illness incidences in EBF infants at 10-14 weeks [OR = 0.27 (CI 0.12-0.64)] and 18-22 weeks [OR = 0.50 (CI 0.27-0.90)]. Conclusions: The prevalence of EBF is suboptimal in our setting, with illness incidences significantly higher in non-EBF children. Appropriate intervention strategies need to be tailored to reinforce early initiation and continuation of EBF throughout the first six months of life.

Study of Common Illnesses Before and After Vaccination: A Risk interval Approach.

OBJECTIVE: To compare the proportion of children who developed a specified illness in the 7 day post-vaccination window, with the background rate of the same event in the 7 day pre-vaccination window. STUDY DESIGN: Risk interval approach (Self-controlled case-series). SETTING: Well Baby Clinic of Christian Medical College, Vellore. PARTICIPANTS: 1602 healthy infants and under-six children presenting for routine vaccination. OUTCOME MEASURES: Episode of any illness. METHODS: The interviewer enquired about any adverse event or illness experienced by the child for each day of the week preceding the administration of age-appropriate vaccines. A second interview (telephonic) was conducted by the same interviewer one week following vaccine administration to enquire about adverse event(s) experienced by the child for each day of the subsequent week using a similar protocol. RESULTS: With multiple vaccines delivered at appropriate ages, common childhood illnesses that could be reported as adverse events following immunization, except fever (RR=5.7, 95% CI=4.50-7.35), occurred at higher rates pre-vaccination. Risk Ratios of fever following whole cell (RR=9.3, 95% CI=6.43-13.52) and acellular (RR=8.5, 95% CI=3.82-18.91) vaccines were similar, with both showing a decreasing trend with increasing age. The gastrointestinal adverse event profile [diarrhea (RR=0.6, 95% CI=0.14-2.51) and vomiting (RR=1.0, 95% CI=0.14-7.10)] for rotavirus vaccine was similar pre- and post-immunization. CONCLUSIONS: Since most adverse events to vaccines are also common childhood illnesses, estimating the background rates of common illnesses is important to accurately ascertain a causal relationship.