A neonatal pneumococcal conjugate vaccine trial in Papua New guinea: study population, methods and operational challenges

Infants in Papua New Guinea (PNG) are at a high risk of invasive pneumococcal disease, and a substantial burden of this falls on children less than six months old. PNG is planning to introduce a pneumococcal conjugate vaccine for infants in the near future, but to make the maximum impact neonatal immunization will have to be considered. To provide evidence on safety and immunogenicity for neonatal and early infant immunization, we undertook an open randomized controlled trial of 7-valent pneumococcal conjugate vaccine (7vPCV). 318 children received 7vPCV at ages 0, 1 and 2 months or at 1, 2 and 3 months or not at all. All children received 23-valent pneumococcal polysaccharide vaccine at age 9 months. This was a large and complex trial: village reporters visited participants weekly during the first year and fortnightly for a further 6 months and nurses monitored self-reported morbidity and collected many thousands of biological samples. The study team was remarkably successful in achieving the study aims, with 18-month follow-up completed on 77% of enrolled children and over 80% of scheduled samples collected. While the results of the trial will be reported elsewhere, this paper discusses the design of the study and dissects out some of the main reasons for its successful completion. Strong community engagement was an essential factor in success and the principles of equitable partnership and service provision led to a strong research partnership. A two-stage consent process, comprising primary assent followed by later informed consent, led to a high drop-out before initial enrolment, but an outstanding retention of those enrolled in the study. We conclude that factors such as strong community participation, reciprocity and a good relationship between the study team and participants are just as important as the technical elements of laboratory testing and data handling in ensuring the success of a vaccine trial in PNG.

Streptococcus pneumoniae serogroups and colony morphology: a look back

From 1985 to 1987, Streptococcus pneumoniae isolates were collected from children under 5 years of age in the Asaro Valley, Papua New Guinea as part of a study on bacterial colonization and respiratory tract infections. Data on serogroup and colony morphology were collected to survey serogroups and associated colony morphologies present in the area and to assess whether colony morphology can be indicative of serogroup. In total, 5989 colonies were examined; serogroups 6, 10, 14, 15, 19, 23, 33, 34, 35 and nonserotypeable strains were the most common and accounted for 77% of all the colonies, with serogroups 6, 19 and 23 accounting for 48%. The majority of colonies displayed the typical draughtsman morphology, though serogroup 10 and non-serotypeable isolates most often displayed a raised colony morphology. Of the 15 mucoid colonies identified 73% were serotype 3, though only 29% of serotype 3 isolates were mucoid. Thus colony morphology is of limited value in identifying the pneumococcal serogroup/serotype apart from mucoid colonies, which are likely to be serotype 3.

Viruses associated with acute lower respiratory tract infections in children from the eastern highlands of Papua New Guinea (1983-1985).

This study, conducted at Goroka Hospital from January 1983 to June 1985, examined the viruses identified in nasopharyngeal aspirates (NPA) and urines collected from 716 hospitalised children with moderate or severe pneumonia, in NPA from 170 children with mild pneumonia treated as outpatients and in NPA from a control group of 428 children attending the outpatient department of Goroka Hospital suffering from minor ailments other than upper or lower respiratory tract infections. One or more viruses were identified from 68%, 51% and 43% of children with moderate or severe pneumonia, mild pneumonia and the control group, respectively. One-third of viruses were identified in conjunction with another virus in both control and sick children. Viral identification rates were highest in children under 1 year of age. Cytomegalovirus, adenoviruses, respiratory syncytial virus (RSV), measles and rhinoviruses were the most frequently identified viruses. RSV was associated with mild as well as moderate and severe disease. No virus was associated with an increased risk of death. Annual epidemics of RSV occurred during the wet season. An epidemic of influenza A virus and also influenza B virus and 3 epidemics of parainfluenza 3 virus occurred during the study period. The high viral identification rates in this study suggest a high frequency of transmission associated with the social structure and environment of Papua New Guinean highland villages and high population mobility.