Tonga Measles Outbreak 2019 - Situation Report #11
1. Summary of Situation
The outbreak of measles in Tonga began in early October 2019, following the return of a team of Tongan rugby players from New Zealand. The index case developed measles while in New Zealand. Subsequently, a further 12 players developed laboratory-confirmed measles after returning to Tonga. The early outbreak involved mainly teenagers from schools on Tongatapu and Vava’u Islands. All 70 villages on Tongatapu Island have reported cases. Small numbers of cases have been identified on the Islands of ‘Eua and Niuatoputapu. Since the initial two waves of the outbreak, cases are now being seen widely in other age groups.
An inter-disciplinary Ministry of Health Epidemic Task Force meets weekly to advise on management of the outbreak. In addition to routine outbreak response activities, a time-limited vaccination program targeting secondary school students and 6-11 months infants was initiated and completed. Mass Vaccination campaign targeting the 10-24-year age group not picked up in the school vaccination program throughout Tonga was completed on Friday 20 December 2019.
Note: Refer to earlier SITREPS for further detail of the initial cases and response.
2. Current Situation
Since the last situation report, 18 new measles cases with onset dates in the last week were reported in Tonga, including 16 cases from the main Island of Tongatapu and 2 cases from Vava’u Island. The cases were 9 males and 9 females respectively and were aged between 5 months and 21 years. The cases did not require hospitalizations. Other cases received within the last week but with earlier onset dates have been included in the cumulative figures and analysed below.
As of 23 December 2019, 596 confirmed or suspected cases of measles have been identified in Tonga. The majority 523 (87.8%) cases in total have occurred on Tongatapu and 63 (10.5%) have occurred on Vava’u Island. Cases have been reported to be mild with 15 hospitalizations with no deaths. The majority of the cases have been managed in home isolation. Given that the duration of illness is typically less than 2 weeks, it is estimated that at least 93% of the 596 reported measles cases will have already recovered from their illnesses
Figure 1 (below) shows the epidemic curve for the current outbreak in Tonga. Most of cases (blue) were reported from the Island of Tongatapu.
Figure 2 demonstrates the breakdown of cases by sex. Consistent with early transmission through male boarding schools, most cases have been among males, with the proportion of cases among females increasing as the outbreak progressed. A total of 94 cases have occurred in children aged less than 5 years, while cases among adolescents and young people continue to form the majority of the cases in this outbreak, with 468 (79%) cases occurring in people aged 10 to 24 years (Table 1 and Figure 3).