Progress towards elimination of measles in Kenya, 2003-2016

Introduction: measles is targeted for elimination in the World Health Organization African Region by the year 2020. In 2011, Kenya was off track in attaining the 2012 pre-elimination goal. We describe the epidemiology of measles in Kenya and assess progress made towards elimination.Methods: we reviewed national case-based measles surveillance and immunization data from January 2003 to December 2016. A case was confirmed if serum was positive for anti-measles IgM antibody, was epidemiologically linked to a laboratory-confirmed case or clinically compatible. Data on case-patient demographics, vaccination status, and clinical outcome and measles containing vaccine (MCV) coverage were analyzed. We calculated measles surveillance indicators and incidence, using population estimates for the respective years.Results: the coverage of first dose MCV (MCV1) increased from 65% to 86% from 2003-2012, then declined to 75% in 2016. Coverage of second dose MCV (MCV2) remained < 50% since introduction in 2013. During 2003-2016, there were 26,188 suspected measles cases were reported, with 9043(35%) confirmed cases, and 165 deaths (case fatality rate, 1.8%). The non-measles febrile rash illness rate was consistently > 2/100,000 population, and "80% of the sub-national level investigated a case in 11 of the 14 years. National incidence ranged from 4 to 62/million in 2003-2006 and decreased to 3/million in 2016. The age specific incidence ranged from 1 to 364/million population and was highest among children aged < 1 year.Conclusion: Kenya has made progress towards measles elimination. However, this progress remains at risk and the recent declines in MCV1 coverage and the low uptake in MCV2 could reverse these gains

Visiting health centers as a risk factor for measles transmission: Kamwenge District, Uganda, April ­ July 2015

Introduction: Uganda has been implementing a one-dose measles vaccination at age 9 months in its national EPI schedule. On 27 April 2015, a measles outbreak, which was confirmed by serum positivity in several patients, occurred in Kamwenge District. Since then, the number of reported measles patients has increased despite the implementation of measures to control the outbreak by the local government. We investigated this outbreak to identify the risk factors for measles transmission, estimate vaccination coverage, determine vaccine effectiveness, and recommend control measures.Methods: we defined a probable case as onset in a Kamwenge District resident of fever and generalized rash from 16 April 2015 onward with ≥ 1 of the following: coryza, conjunctivitis, or cough. A confirmed case was a probable case with positive measles-specific IgM in patient serum. For case-finding we reviewed medical records and found patients in the community with the help of the village health team. We determined vaccination histories by vaccination cards or interviews. In a case-control study, we compared the exposure histories of 50 probable case-persons with 200 asymptomatic control-persons during case-persons' exposure period (i.e., between minimum and maximum incubation). We matched case- and control-persons by age and residence village. We estimated vaccination coverage for children aged ≤ 2 years based on the percent of control-children vaccinated. Results: we identified 213 probable/ confirmed cases from 3 affected sub-counties (attack rate = 5.1/10,000). The epidemic curve showed sustained community transmission. The case-control study showed that 42% (21/50) of case-persons and 12% (23/200) of control-persons visited health centers during case-persons' exposure period (AORM-H = 6.1; 95% CI = 2.7-14). Vaccination coverage among children aged ≤ 2 years was 58% (95% CI = 47-68%). The vaccine effectiveness was 80% (95% CI = 35-94%). We found that all health centers were crowded, with no triaging system to separate suspect measles patients from patients with other illnesses.Conclusion: exposures to measles patients at crowded health centers, low vaccination coverage, and suboptimal vaccine effectiveness facilitated measles transmission in this outbreak. We recommended an emergency immunization campaign targeting young children, triaging and isolating suspect measles patients at health centers, and introducing a second dose of measles vaccine in the immunization schedule

Innovations en vaccinologie: enjeux et perspectives pour l'Afrique

La vaccination est incontestablement l'une des interventions de santé publique les plus efficaces et les plus rentables qui soient. Les vaccins continuent de révolutionner notre capacité à prévenir les maladies et à améliorer la santé. Avec toutes les avancées technologiques, nous sommes en mesure d'étendre les avantages des vaccins à plus de gens et de fournir une meilleure protection contre les maladies infectieuses mortelles. Toutefois, avec le développement incessant de nouvelles souches microbiennes à travers le monde, la recherche en vaccinologie se doit d'innover continuellement. D'énormes progrès ont été réalisés pour améliorer la couverture vaccinale et introduire de nouveaux vaccins en Afrique. De nouveaux types de vaccins associés à des outils de vectorisation, d'administration et de délivrance spécifiques mais aussi des adjuvants susceptibles de moduler finement la réponse immunitaire sont attendus dans le futur. En Afrique, il est nécessaire de développer une approche régionale afin de répondre efficacement aux nombreux défis. Une meilleure information, la formation des personnels de santé en vaccinologie et des recherches bien ciblées sont les clés des futurs accomplissements dans le domaine

Missed opportunities and barriers for vaccination: a descriptive analysis of private and public health facilities in four African countries

Introduction: missed opportunities and barriers to vaccination limit progress toward achieving high immunization coverage and other global immunization goals. Little is known about vaccination practices contributing to missed opportunities and barriers among private healthcare providers in Africa.Methods: Service Provision Assessments (SPA) of representative samples of health facilities in four African countries (Kenya, Tanzania, Senegal, Malawi) in 2010-2015 were used to describe missed opportunities and barriers for vaccination in public, private for-profit, private not-for-profit and faith-based facilities. Data included vaccination practices, observations during sick child and antenatal visits, and exit interviews following sick child visits.Results: data from 3,219 health facilities, 11,613 sick child visits and 8,698 antenatal visits were included. A smaller proportion of for-profit facilities offered child vaccination services (country range, 25-37%) than did public facilities (range, 90-96%). The proportion of facilities offering pentavalent vaccine (diphtheria, pertussis, tetanus, hepatitis B and Haemophilus influenza type b antigens) daily ranged 0-77% across countries and facility types. Less than 33% of for-profit facilities in any country offered measles vaccination daily. A minority of public or private providers assessed the child's vaccination status during a sick child visit (range by country and facility type, 14-44%), or offered tetanus toxoid during antenatal visits (range, 19-51%). Very few providers discussed the importance of newborn vaccination. Conclusion: substantial missed opportunities for, and barriers to, vaccination were identified across this representative sample of health facilities in four African countries. Strategies are needed to ensure that private and public providers implement practices to minimize barriers and missed opportunities for vaccination

Au sujet d'un paradoxe; ou comment repondre aux rumeurs parfois desagreables a propos des cas de rougeole survenant chez des sujets vaccines

En situation d'epidemie; il est frequent d'entendre que beaucoup de malades rougeoleux avaient pourtant ete vaccines; que le vaccin est inefficace; que les gens de la sante ne font pas du travail serieux. Ce genre de plainte; bien comprehensible lorsqu'elle est formulee par des parents confrontes a cette situation facheuse; est malheureusement amplifiee par des professionnels de la sante; devient rumeur; est reprise par les medias. Le directeur national du programme elargi de vaccination est convoque chez le ministre; le responsable regional chez le haut-commissaire ou le prefet; etc

A low-cost; community-based measles outbreak investigation with follow-up action

An outbreak of measles in Kampala; Uganda; in 1990 raised concern about the effectiveness of the measles vaccine that was used. The Uganda EPI Programme and the medical office of the Kampala City council therefore conducted a community-based investigation; with door-to-door interviews in two selected communities. They revealed 68 measles cases ranging in age from 5 months to 12 years; the highest age-specific attack rate (32) was found in children aged 12 to 23 months. BCG immunization coverage was high (85); but measles immunization coverage was moderate (48). One community; served by a mobile clinic; presented a vaccine efficacy of only 55. Responses by mothers revealed that many had failed to have their children completely immunized because of a lack of information; and because of difficulties in access to the services. In a follow -up; community leaders initiated monthly checking of immunization cards of both children and mothers. The low vaccine efficacy found in one of the communities resulted in a thorough assessment of the city's cold chain. This community-based approach proved to be cost-effective and practical for identifying the obstacles to effective immunization delivery

A low-cost; community-based measles outbreak investigation with follow-up action

An outbreak of measles in Kampala; Uganda; in 1990 raised concern about the effectiveness of the measles vaccine that was used. The Uganda EPI programme and the medical office of the Kampala City Council therefore conducted a community-based investigation; with door-to-door interviews in two selected communities. They revealed 68 measles cases ranging in age from 5 months to 12 years; the highest age-specific attack rate (32pc) was found in children aged 12 to 23 months. BCG immunization coverage was high (85pc); but measles immunization coverage was moderate (48pc). One community; served by a mobile clinic; presented a vaccine efficacy of only 55pc. Responses by mothers revealed that many had failed to have their children completely immunized because of a lack of information; and not because of difficulties in access to the service. In a follow-up; community leaders initiated monthly checking of immunization cards of both children and mothers. The low vaccine efficacy found in one of the communities resulted in a thorough assessment of the city's cold chain. This community-based approach proved to be cost-effective and practical for identifying the obstacles to effective immunization delivery

Low seroconversion rates to measles vaccine among children in Nigeria

The Nigerian Expanded Programme on Immunization (EPI) was assessed with particular reference to measles immunization. Of 150 children who received measles vaccine at the Institute of Child Health, University of Ibadan, Nigeria, 82 (54.7%) seroconverted. The immune response was directly related to the titre of the vaccines used. Vaccines whose titres were 10(-1) to 10(1.7) stimulated immune responses in 0-25% of vaccinees, those with titres in the range 10(-2.1) to 10(-2.5) stimulated responses in 12-47.6%, while those with titres of 10(-2.7) to 10(-3.4) stimulated responses in 87.5-100% of vaccinees. Only one of the vaccines used had a titre that met the minimum WHO required standard of log 10(-3) TCID50 at the point of vaccination

Measles in a West African nomadic community

A serological survey was conducted among Tuareg nomads to determine their level of immunity to measles. More than half (57.9%) of the children under 10 years of age did not have detectable antibodies to measles, suggesting that transmission of the disease is low in this mobile population. Mothers' reports of their children's history of measles were accurate (positive predictive value 93.9% for under-5-year-olds). Nomads are a reservoir of susceptible individuals who require immunization strategies adapted to their particular life-styles. These can be implemented at relatively low cost

Measles epidemic in Harare, Zimbabwe, despite high measles immunization coverage rates

Despite rapidly increasing measles immunization coverage in Harare city, measles remains endemic, and regular outbreaks occur. The most recent occurred in 1988, when the measles immunization coverage was 83%. We have carried out a retrospective study of the clinical and epidemiological features of this outbreak to assess whether the present immunization policy needs to be changed. Of 4357 cases of measles seen at primary health care centres and hospitals in Harare during the outbreak, 1399 (32%) were severe or involved complications that required hospital admission. The peak incidence occurred among under-2-year-olds, followed by that among 5-7-year-olds. Poor nutritional status was significantly more frequent among children who were hospitalized and among those who died. A total of 59% of all cases aged 9-59 months had documented evidence of measles immunization. The most frequent complications, which occurred most often among under-5-year-olds, were diarrhoea with dehydration, pneumonia, laryngotracheobronchitis, and convulsions, which together affected 56% of hospitalized cases. The hospital case fatality rate was low (1.43%). In Harare, measles transmission remains a problem, despite high measles immunization coverage rates; the failure rate for the standard Schwarz measles vaccine also appears to be high. There is a need to reduce the number of measles cases among under-9-month-olds and young children. Further studies into alternative measles vaccines and schedules are required

Lack of efficacy of the standard potency Edmonston-Zagreb live, attenuated measles vaccine in African infants

The efficacy of standard potency Edmonston-Zagreb (E-Z) measles vaccine was tested in a randomized trial of Black infants in a rural area of South Africa where a measles epidemic was occurring. The following immunization schedules were used: 48 infants aged 4-8.5 months who received 3.9 log 50 infectious units of E-Z vaccine (group A); 48 infants aged 4-8.5 months who received 3.28 log 50 infectious units of Schwarz vaccine (group B); and 28 infants aged greater than 9 months who received 3.28 log 50 infectious units of Schwarz vaccine and served as controls (group C). For infants aged less than 23 weeks who were given either the E-Z or Schwarz vaccine, the number of seropositives was low (28%), irrespective of the pre-vaccination level of measles antibody. There was a higher number of seropositives (68%) among those in the age range greater than 23 weeks to less than 36 weeks who received the E-Z vaccine rather than the Schwarz vaccine (36%). When administered to children aged greater than 36 weeks, the Schwarz vaccine produced a satisfactory, though suboptimal response rate (61%). There was no correlation between seropositivity and pre-vaccination measles antibody status. Use of the standard dose of E-Z vaccine may have been one of the factors for this poor response, and this supports the WHO recommendation that titres higher than the standard potency vaccine are needed if 6-month-old infants are to be successfully immunized against measles

Antibody response to measles immunization at seven months old in rural Ghanaian infants

A serological study was carried out in three rural communities in Southern Ghana in order to determine the optimal age for measles immunization. The live hyperattenuated measles vaccine (Schwarz strain) was inoculated subcutaneously into infants aged three to eleven months. The maternal measles antibodies in the infants started decreasing after 7 months; while the seroconversion rate after the immunization was increasing after 6 months. Forty seven infants were given the measles vaccines at the age of 7 months. The seroconversion rate was 91.5 per cent. There were no side effects. These results indicate that measles immunization can be administered effectively at the age of 7 months

High incidence of measles in previously vaccinated children in Dar es Salaam Tanzania: a major issue for concern

A new finding to emerge from the data is that at all ages above 13 months; more vaccinated children were infected with measles. It is recommended to assess seroconversion in children who have been vaccinated at known ages so as to ascertain what proportion actually seroconvert