Eric Wiesen

Impact of measles outbreak response vaccination campaign in Dar es Salaam, Tanzania.

We assessed the impact of a measles outbreak response vaccination campaign (ORV) in Dar es Salaam, Tanzania. Age-specific incidence rates were calculated before and after the ORV. Incidence rate ratios for the two time periods were compared and used to estimate expected cases and deaths prevented by ORV. The ratio of measles incidence rates in the age groups targeted and not targeted by ORV decreased from 5.8 prior to ORV to 1.8 (p<0.0001) after; 506 measles cases and 18 measles deaths were likely averted. These results support the need for revised recommendations concerning ORV in general settings in Africa.

Measles outbreak in Tanzania, 2006-2007

We conducted a measles outbreak investigation in Dar es Salaam, Tanzania. Surveillance data were analyzed; a susceptibility profile developed, and case-control study conducted. The age distribution of cases peaked among those <2, 5-7, and > or =18 years, corresponding to the age distribution of susceptibles. Risk factors included being unvaccinated (aOR=5.7, p<0.01) or having received one dose of vaccine compared to two (aOR=2.4, p=0.01), being younger, and having a less-educated caretaker. Vaccine effectiveness was 88% (one dose) and 96% (two doses). Results highlight the importance of receiving one dose of measles vaccine, and the added benefit of two doses.

Prevention of infection-related cancers in the WHO Western Pacific Region

A considerable number of infectious agents have been classified as human carcinogens Group 1 by the International Agency for Research on Cancer. Major infection-related cancers such as cancers of nasopharynx (53%), stomach (60%) and liver (63%) occur in the World Health Organization Western Pacific Region. Many infection-related cancers are preventable, particularly those associated with human papilloma virus, Helicobacter pylori, human immunodeficiency virus-I, hepatitis B virus and hepatitis C virus and liver flukes. Mongolia shows the highest prevalence of hepatitis B virus and hepatitis C virus, and China shows the highest prevalence of Helicobacter pylori. Chronic infection is attributable for 17-28% of overall cancer incidence or mortality in China, Japan and Korea. Through infant immunization for hepatitis B, 30 of 37 countries and areas in the Western Pacific Region have reached the 2012 milestone of chronic hepatitis B virus infection prevalence of <2% in 5-year-old children and countries and areas of the region are now striving toward reaching the regional goal of <1% by 2017. Human papilloma virus immunization program is implemented either by government funding or, in some low-income countries, by public and private sector organizations. Cervical cancer screening via visual inspection with acetic acid or Pap smear is available in many Western Pacific Region Member States. More efforts are needed to implement new World Health Organization guide to vaccinate 9- to 13-year-old girls with two doses of human papilloma virus vaccine, and use human papilloma virus tests to screen women to prevent and control cervical cancer including guaranteed monitoring and appropriate follow-up for abnormal results.

Progress towards hepatitis B prevention through vaccination in the Western Pacific, 1990–2014

Hepatitis B infections are responsible for more than 300 thousand deaths per year in the Western Pacific Region. Because of this high burden, the countries and areas of the Region established a goal of reducing hepatitis B chronic infection prevalence among children to less than 1% by 2017. This study was conducted to measure the progress in hepatitis B prevention and assess the status of achievement of the 2017 Regional hepatitis B control goal. A literature review was conducted to identify studies of hepatitis B prevalence in the countries and areas of the region, both before and after vaccine introduction. A mathematical model was applied to assess infections and deaths prevented by hepatitis B vaccination and hepatitis B prevalence in countries without recent empirical data. The majority of countries and areas (22 out of 36) were estimated to have over 8% prevalence of chronic hepatitis B infection among persons born before vaccine introduction. After introduction of hepatitis B vaccine, most countries and areas (24 out of 36) had chronic infection prevalence of less than 1% among children born after vaccine introduction. It was estimated that in the past 25 years immunization programmes in the Western Pacific Region have averted 7,167,128 deaths that would have occurred in the lifetime of children born between 1990 and 2014 if hepatitis B vaccination programmes had not been established. Regional prevalence among children born in 2012 was estimated to be 0.93%, meaning that the Regional hepatitis B control goal was achieved. While additional efforts are needed to further reduce hepatitis B transmission in the region, this study demonstrates the great success of the hepatitis B vaccination efforts in the Western Pacific Region.

Assessment of the hepatitis B birth dose vaccination program, Papua New Guinea, 2014.

INTRODUCTION Papua New Guinea (PNG) implemented hepatitis B birth dose (BD) vaccination in 2005 yet since that time coverage has remained low, allowing mother-to-child transmission to occur. We conducted a field assessment of the BD vaccination program to develop strategies for improving the BD coverage. METHODS We selected five provinces with higher hepatitis B prevalence and five with lower prevalence based on the results of a 2013 hepatitis B serological survey. Within each province, we interviewed district and provincial health officers, health workers, village volunteers, and caregivers from ten randomly selected health facilities. Data were collected on knowledge, practice, vaccine management and data recording/reporting. To identify enabling factors and barriers, we compared health facilities with higher BD coverage with those with lower coverage, and compared caregivers whose children received BD with those whose children did not. RESULTS Overall timely BD coverage was 31% and BD vaccination was taking place in 81% of sampled health facilities. Lack of cold chain and vaccine were the major reasons for not providing the BD. Insufficiencies in supervision, vaccine management, community outreach, and data management were identified as obstacles to achieving high timely hepatitis B BD coverage. Good supervision, knowledge of hepatitis B and hepatitis B vaccination, antenatal care including information about the hepatitis B BD, provision of vaccine refrigerators in maternity wards, and outreach vaccination for home deliveries were associated with higher timely BD coverage. DISCUSSION Several steps will likely be effective in improving BD coverage: strengthening training and supervision among health workers and officers, educating caregivers on the benefits of the BD and delivery in health facilities, improving vaccine management, and improving data quality. Considerable effort and leadership will be needed to achieve these steps.

Impact of Adverse Events Following Immunization in Viet Nam in 2013 on chronic hepatitis B infection.

Highlights • Hepatitis B vaccination coverage dropped significantly after Adverse Events Following Immunization in Viet Nam in 2013.• We estimated 17,456 hepatitis B-related deaths would occur due to the drop in vaccination coverage.• Swift responses to reported adverse events following immunization are needed to maintain consumer confidence in vaccination.

Stability of the Age Distribution of Measles Cases Over Time During Outbreaks in Bangladesh, 2004–2006

Despite recommendations from WHO to conduct measles outbreak response vaccination campaigns based on the age distribution of cases at the beginning of an outbreak, few data exist to specifically examine whether the age distribution of cases remains constant over time in a measles outbreak. This analysis explores this question with use of measles outbreak surveillance data from Bangladesh from the period 2004-2006. Pearson χ(2) tests were conducted of age distributions over 2 periods during 41 large laboratory-confirmed measles outbreaks. Statistically significant changes in age distribution over time were observed in 24% of the outbreaks. No single pattern was detected in the shifts in age distribution; however, an increase in the proportion of cases occurring among infants <9 months of age was evident in 6 outbreaks. These findings suggest a need to consider the possibility of a shift in the age distribution over time when planning an outbreak response vaccination campaign.

Approaches to Vaccination Among Populations in Areas of Conflict

Vaccination is an important and cost-effective disease prevention and control strategy. Despite progress in vaccine development and immunization delivery systems worldwide, populations in areas of conflict (hereafter, “conflict settings”) often have limited or no access to lifesaving vaccines, leaving them at increased risk for morbidity and mortality related to vaccine-preventable disease. Without developing and refining approaches to reach and vaccinate children and other vulnerable populations in conflict settings, outbreaks of vaccine-preventable disease in these settings may persist and spread across subnational and international borders. Understanding and refining current approaches to vaccinating populations in conflict and humanitarian emergency settings may save lives. Despite major setbacks, the Global Polio Eradication Initiative has made substantial progress in vaccinating millions of children worldwide, including those living in communities affected by conflicts and other humanitarian emergencies. In this article, we examine key strategic and operational tactics that have led to increased polio vaccination coverage among populations living in diverse conflict settings, including Nigeria, Somalia, and Pakistan, and how these could be applied to reach and vaccinate populations in other settings across the world.

Progress Toward Poliomyelitis Eradication — Nigeria, January–December 2017

Nearly three decades after the World Health Assembly launched the Global Polio Eradication Initiative in 1988, four of the six World Health Organization (WHO) regions have been certified polio-free (1). Nigeria is one of three countries, including Pakistan and Afghanistan, where wild poliovirus (WPV) transmission has never been interrupted. In September 2015, after >1 year without any reported WPV cases, Nigeria was removed from WHOs list of countries with endemic WPV transmission (2); however, during August and September 2016, four type 1 WPV (WPV1) cases were reported from Borno State, a state in northeastern Nigeria experiencing a violent insurgency (3). The Nigerian government, in collaboration with partners, launched a large-scale coordinated response to the outbreak (3). This report describes progress in polio eradication activities in Nigeria during January-December 2017 and updates previous reports (3-5). No WPV cases have been reported in Nigeria since September 2016; the latest case had onset of paralysis on August 21, 2016 (3). However, polio surveillance has not been feasible in insurgent-controlled areas of Borno State. Implementation of new strategies has helped mitigate the challenges of reaching and vaccinating children living in security-compromised areas, and other strategies are planned. Despite these initiatives, however, approximately 130,000-210,000 (28%-45%) of the estimated 469,000 eligible children living in inaccessible areas in 2016 have not been vaccinated. Sustained efforts to optimize surveillance and improve immunization coverage, especially among children in inaccessible areas, are needed.