Relationship between nutritional status and the ability of six to twelve- weeks infants to sero-convert to rotavirus vaccination

Abstract

Live attenuated oral vaccines against rotavirus have been shown to be less efficacious in children from developing countries compared to developed countries. Reasons for this disparity are not fully understood. This study aimed to investigate the potential association between indicators of nutritional status (vitamin A status, weight for age, height for age and mid-upper arm circumference) of the infants and sero-conversion among Zambian infants routinely immunized with rotavirus vaccine, Rotarix™. A total of 1320 infants were assessed for enrolment and420 infants were recruited at infant age 6-12 weeks in Lusaka, Zambia. Clinical information and samples were collected at baseline and at one month following the second dose of rotavirus vaccine. Only 208 infant samples were analyzed at baseline and one month after vaccination to determine infant nutritional status (vitamin A status, weight for age, height for age status and mid-upper arm circumference. Vitamin A status and serum rotavirus-specific IgA were determined using standardized Enzyme Linked Immuno-sorbent Assay methods. The anthropometric indices were interpreted using WHO growth standards. Sero-conversion was defined as a ≥ 4 fold rise in serum IgA titre from baseline to one-month post Rotarix™ dose 2, while sero-positivity of IgA was defined as serum titre ≥ 40. Pearson Chi-squared test was used to investigate the association of sero-conversion and categorical factors (i.e. sex, vitamin A status, weight for age, height for age, mid-upper arm circumference at baseline and serum IgA sero-positivity). The sero-conversion frequency to rotavirus was 57.2% (119/208) and baseline infant sero-positivity to rotavirus was 23.1% (48/208). Baseline vitamin A deficiency, underweight and stunting were 78.9% (164/208), 6.7% (14/208) and 52.4% (109/208), respectively. Base-line Infant moderate acute malnutrition was 38.0% (79/208208) and severe acute malnutrition was 12.50% (26/208) as determined by the infant mid-upper arm circumference. There was no evidence of association between infant serum IgA sero-conversion and nutritional variables; serum vitamin A deficiency (p=0.882), stunting (p=0.905), underweight (p=0.243), Mid-Uper arm circumference (p=0.565) and infant baseline serum IgA sero-positivity (p=0.832). Poor IgA sero-conversion frequency observed in this cohort was not influenced by nutritional factors indicated by infant serum vitamin A status, weight for age, height for age and mid-upper arm circumference. Early infant exposure to rotavirus infection, determined by infant serum IgA sero-positivity levels did not influence sero-conversions frequencies in this cohort. These factors may have other effects later in childhood, as no difference was observed among seroconvertors and non-seroconvertors to rotavirus vaccination in the 6-12 weeks age group. Further research is needed to better understand vaccine sero-conversion. Key word: Rotavirus vaccine, rotavirus, seroconvert, Zambia, Infant