Abstract
BackgroundVaccination is a mainstay of preventive healthcare, reducing the incidence of serious childhood infections. Ecological studies have demonstrated an inverse association between markers of high ambient ultraviolet (UV) radiation exposure (e.g., sunny season, low latitude of residence) and reduction in the vaccination-associated immune response. Higher sun exposure on the day prior to and spanning the day of vaccination has been associated with a reduced antigen-specific immune response independent of skin pigmentation. The South African Department of Health’s Expanded Programme on Immunisation provides free vaccinations in government primary health care clinics. In some areas, these clinics may have only a small waiting room and patients wait outside in full sun conditions. In rural areas, patients may walk several kilometres to and from the clinic. We hypothesised that providing sun protection advice and equipment to mothers of children (from 18 months) who were waiting to be vaccinated would result in a more robust immune response for those vaccinated.MethodsWe conducted an intervention study among 100 children receiving the booster measles vaccination. We randomised clinics to receive (or not) sun protection advice and equipment. At each clinic we recorded basic demographic data on the child and mother/carer participants, their sun exposure patterns, and the acceptability and uptake of the provided sun protection. At 3–4 weeks post-vaccination, we measured measles IgG levels in all children.DiscussionThis is the first intervention study to assess the effect of sun protection measures on vaccine effectiveness in a rural, real-world setting. The novel design and rural setting of the study can contribute much needed evidence to better understand sun exposure and protection, as well as factors determining vaccine effectiveness in rural Africa, and inform the design of immunisation programmes. (TRN PACTCR201611001881114, 24 November 2016, retrospective registration)
Highlights
Vaccination is a mainstay of preventive healthcare, reducing the incidence of serious childhood infections
We have shown that, in young adults, personal exposure to higher levels of solar UV radiation on the day prior to vaccination, and in the peri-vaccination period, was associated with a significant decrease in the antigen-specific cell-mediated immune response to a novel antigen, keyhole limpet haemocyanin [21]
In light of the recent evidence showing that higher levels of sun exposure in the period leading up to and immediately following vaccination is associated with a demonstrable decrease in antigen-specific immune response, we hypothesised that providing sun protection advice and equipment to mothers of children who are waiting for measles vaccinations will result in an enhanced immune response
Summary
Setting The study was conducted in primary health care clinics in the Greater Giyani Local Municipality, Limpopo Province (see Fig. 1). Children at control and intervention sites received the measles vaccination according to the Health Department protocol (including routine height and weight measurements) and using the standard vaccine preparation method, and were asked to return to the clinic 3–4 weeks later for blood testing. Following the blood draw visit, the mothers in the intervention group completed a brief questionnaire on their acceptance and use of the sun protection equipment and participants at the control site received the sun protection equipment. We will use multiple linear regression to examine the factors associated with levels of measles antibodies (across all children tested), including age, sex, body mass index (weight and height), HIV status, sun exposure, sun protection coverage and clinic attended (i.e., intervention versus control group). This number will allow estimation of recruitment rates within clinics with 95% Confidence Intervals (CI) within ± 10% and within clinic estimation of outcomes with 95% CI within ± 14% for proportions and ± 0.3 standard deviations for continuous measures, and differences between groups of 28% for binary measures and 0.6 standard deviations for continuous measures in univariable and regression analyses
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