Elizabeth Sek Hoon Khor’s research while affiliated with National University of Singapore and other places

The objective of this study was to assess and compare the reactogenicity of GlaxoSmithKline (GSK) Biologicals' diphtheria-tetanus-tricomponent acellular pertussis vaccine (DTPa) and the locally used combined diphtheria-tetanus-whole-cell pertussis vaccine (DTPw) as a primary vaccination course in healthy infants at the age of 3, 4 and 5 months. A phase IV, single-blinded, randomized comparative clinical study involved one hundred and eighty healthy infants with two study groups in a 2:1 ratio to receive either DTPa or DTPw vaccine which were administered intramuscularly at the right anterior-lateral aspect of the thigh. The incidence and intensity of local solicited symptoms such as pain, redness and swelling at injection site and general solicited symptoms such as fever and fussiness were evaluated. Serious adverse events were followed for one month after each vaccination. The overall incidence of local and general symptoms was significantly higher in the group receiving locally used DTPw vaccine as compared to the group receiving GSK DTPa vaccine. Solicited local symptoms, pain (47.4% vs 15.1%), redness (95.9% vs 84.9%) and swelling (46.2% vs 18.5%), were reported more frequently in the group receiving DTPw vaccine than in the group receiving DTPa vaccine. Fever (> or = 37.5 degrees C) (52% vs 14.6%) and fussiness (60.8% vs 33.6%) were also more commonly reported in the DTPw group. There were six serious adverse events reported (4 with DTPw and 2 with DTPa). None of them related to the study vaccines, as considered by the investigators. Thus it was found that GSK Biologicals' DTPa vaccine was significantly less reactogenic as compared to the locally used DTPw vaccine manufactured by Commonwealth Serum Laboratories when administered as a 3-dose primary vaccination course to healthy infants at the age of 3, 4 and 5 months in Singapore.

This study was aimed to investigate the sensitization pattern to a range of common allergens in young Singaporean children. A cross-sectional study involving 75 children aged below 3 years was carried out. They presented between December 1995 and April 2000 with symptoms of asthma, rhinitis, eczema, or food allergy. Their levels of allergen-specific serum IgE to a panel of foods (egg white, milk, soy protein, shrimp, wheat and peanut), pet dander, dust mites and cockroaches were measured with Pharmacia CAP System radioallergosorbent test kits. Serum IgE levels greater than 0.35 kU/l represented a positive result. Four children could not be tested with the complete panel because of insufficient serum. The prevalence of sensitization was highest for cow's milk (45.9%) followed by egg white (38.7%), dust mites Dermatophagoides pteronyssinus (31.4%) and Blomia tropicalis (25.5%). Sensitization to ingested allergens was significantly more prevalent in children aged 1 year or younger than in the older children (70.4% of those below 1 year, and 50% of those aged 1-3 years; p < 0.02). Sensitization to inhaled allergens, such as dust mites, was more likely to manifest as respiratory symptoms (allergic rhinitis and asthma), while ingested allergens were associated with gastrointestinal symptoms and eczema (p < 0.001). It was concluded that infants and young children are at high risk of sensitization to common environmental substances. Allergen avoidance is therefore important even in the very young. The prevalence of sensitization to food allergens is higher compared to inhalant allergens in young children.