Mass measles immunization campaign: experience in the Hong Kong Special Administrative Region of China.
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After the 1988 measles outbreak, annual notification rates for measles in Hong Kong SAR between 1989 and 1999 were 0.4-4.9 per 100 000, with peaks in 1992, 1994 and 1997. The first half-year incidence rates per 100 000 were 2.3 in 1997, 0.5 in 1995 and 1.2 in 1996. Monthly notification rates increased from a baseline of <10 cases to 59 in May 1997. Serological surveillance showed only 85.5% of children aged 1-19 years had measles antibodies. An epidemic, mainly because of failure of the first dose to produce immunity, seemed imminent in mid-1997. A mass immunization campaign targeted children aged 1-19 from July to November 1997. The overall coverage was 77%. The rate of adverse events was low. After the campaign, measles notification fell to 0.9 per 100 000 in 1998. A two-dose strategy and supplementary campaigns will maintain measles susceptibility at levels low enough to make measles elimination our goal. (+info)
The average cost of measles cases and adverse events following vaccination in industrialised countries.
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BACKGROUND: Even though the annual incidence rate of measles has dramatically decreased in industrialised countries since the implementation of universal immunisation programmes, cases continue to occur in countries where endemic measles transmission has been interrupted and in countries where adequate levels of immunisation coverage have not been maintained. The objective of this study is to develop a model to estimate the average cost per measles case and per adverse event following measles immunisation using the Netherlands (NL), the United Kingdom (UK) and Canada as examples. METHODS: Parameter estimates were based on a review of the published literature. A decision tree was built to represent the complications associated with measles cases and adverse events following immunisation. Monte-Carlo Simulation techniques were used to account for uncertainty. RESULTS: From the perspective of society, we estimated the average cost per measles case to be US$276, US$307 and US$254 for the NL, the UK and Canada, respectively, and the average cost of adverse events following immunisation per vaccinee to be US$1.43, US$1.93 and US$1.51 for the NL, UK and Canada, respectively. CONCLUSIONS: These average cost estimates could be combined with incidence estimates and costs of immunisation programmes to provide estimates of the cost of measles to industrialised countries. Such estimates could be used as a basis to estimate the potential economic gains of global measles eradication. (+info)
Influenza vaccinations in Northern Ireland: are older patients missing out?
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BACKGROUND: Influenza is a common respiratory disease that may affect a large proportion of the population annually. Vaccination is recommended for those most at risk of complications; namely everyone aged 65 and over and those under 65 who are immunosuppressed or who have chronic disease. OBJECTIVE: To explore the variations in influenza vaccination rates for the winter of 2000, with special reference to uptake amongst older patients. DESIGN: An audit of vaccination rates amongst 12 practices that participate in the Northern Ireland Data Retrieval in Primary Care Project. METHODS: Data were extracted from the practice computers; Read codes were used to determine if the patient was immunosuppressed or suffered from chronic heart, lung or renal disease or had diabetes mellitus. The postcode of residence was used as a proxy for residence in a nursing or residential home as this could not be determined directly from the data. Multiple regression analysis was used to determine which factors were significantly related to vaccination uptake. RESULTS: We vaccinated 10,427 patients in these practices against influenza with a vaccination rate of 65.2% for the over-65 population. Uptake rates peaked at age 85 and declined thereafter so that only half of those aged over 90 had been vaccinated. This age related decline in vaccination rates was evident in ten of the twelve practices. The presence of chronic disease increased the likelihood of vaccination even amongst older patients. Logistic regression confirmed the decline in uptake rates at older ages and suggested that patients who shared the address of a nursing or residential home were less likely to have been vaccinated. CONCLUSIONS: We feel that the current monitoring of influenza vaccination rates needs to be extended so that uptake amongst those most at risk, namely the very oldest and those in nursing and residential homes, can be adequately assessed. (+info)
Molecular epidemiological analysis of the changing nature of a meningococcal outbreak following a vaccination campaign.
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A serogroup C meningococcal outbreak that occurred in an Israeli Arab village led to a massive vaccination campaign. During the subsequent 18 months, new cases of type B Neisseria meningitidis infection were revealed. To investigate the influence of vaccination on bacteriological epidemiology, bacteria were isolated from individuals at the outbreak location, patients with several additional other sporadic cases, and patients involved in another outbreak. Haploid bacterial genomic DNA was mixed with a consensus PCR product to form a heteroduplex state that enabled multilocus sequence typing (MLST) to be combined with denaturing high-performance liquid chromatography (DHPLC) for a novel high-throughput molecular typing method called MLST-DHPLC. A 100% correlation was found to exist between the sequencing by MLST alone and the MLST-DHPLC method. Independent molecular typing by repetitive extragenic palindromic PCR discriminated the neisserial clones as well as the MLST-DHPLC method did. The occurrence of type B N. meningitidis in the postvaccination period might be attributed to the selection pressure applied to the bacteria by vaccination, suggesting a possible unwarranted outcome of vaccination with the quadrivalent vaccine for control of a serogroup C meningococcal outbreak. This is the first time that DHPLC has been applied to the genotyping of bacteria, and it proved to be more efficient than MLST alone. (+info)
The risk of aseptic meningitis associated with the Leningrad-Zagreb mumps vaccine strain following mass vaccination with measles-mumps-rubella vaccine, Rio Grande do Sul, Brazil, 1997.
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BACKGROUND: Few data are available on the risk of aseptic meningitis following vaccination with the Leningrad-Zagreb (L-Z) strain of mumps vaccine. In 1997 the mumps vaccine was introduced into the state of Rio Grande do Sul in Brazil through mass vaccination with mumps-measles-rubella (MMR), targeting children aged 1-11 years. Five municipalities used exclusively MMR vaccine containing the L-Z strain of mumps. An outbreak of aseptic meningitis was observed shortly after the mass campaign. METHODS: To estimate the risk of aseptic meningitis associated with this strain, we analysed vaccination and meningitis case surveillance data from the selected municipalities. A case of vaccine-associated aseptic meningitis was defined as one with a pleocytosis of 10-1,500 leukocytes/ml and occurring within 15-35 days after vaccine receipt. RESULTS: We estimated a risk of 2.9 cases per 10,000 doses of L-Z administered, equivalent to 1 case per 3,390 doses administered. The overall risk of aseptic meningitis following the campaign was increased 12.2-fold (95% CI: 6.0-24.7) compared with the same period in 1995-1996. Following the mass campaign, the incidence of mumps declined 93% during 1998-2000. CONCLUSIONS: Vaccination with the L-Z strain of mumps vaccine as part of a mass campaign was associated with a significantly increased risk of aseptic meningitis. Decisions about type of mumps vaccine and mumps vaccination strategies must consider vaccine safety issues in addition to other criteria. (+info)
Mass vaccination campaign following community outbreak of meningococcal disease.
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During December 12-29, 1998, seven patients ages 2-18 years were diagnosed with serogroup C meningococcal disease in two neighboring Florida towns with 33,000 residents. We evaluated a mass vaccination campaign implemented to control the outbreak. We maintained vaccination logs and recorded the resources used in the campaign that targeted 2- to 22-year-old residents of the two towns. A total of 13,148 persons received the vaccinations in 3 days. Vaccination coverage in the target population was estimated to be 86% to 99%. Five additional cases of serogroup C meningococcal disease occurred in the community during the year after the campaign began, four in patients who had not received the vaccine. The cost of control efforts was approximately $370,000. Although cases continued to occur, the vaccination campaign appeared to control the outbreak. Rapid implementation, a targeted approach, and high coverage were important to the campaign's success. (+info)
Capsule switching among C:2b:P1.2,5 meningococcal epidemic strains after mass immunization campaign, Spain.
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A mass immunization campaign for 18-month to 19-year-olds was undertaken in Spain in 1996-1997 because of an epidemic of serogroup C meningococcal disease associated with a C:2b:P1.2,5 strain belonging to the A4 lineage. Surveillance for the "capsule-switching" phenomenon producing B:2b:P1.2,5 isolates was undertaken. Of 2,975 meningococci characterized, B:2b:P1.2,5 and B:2b:P1.2 antigenic combinations were found in 18 isolates; 15 meningococci were defined as serogroup B belonging to the A4 lineage. (+info)
Conventional influenza vaccination is not associated with complications in working-age patients with asthma or chronic obstructive pulmonary disease.
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By using a nested case-control design, the authors studied the effectiveness of the influenza vaccine in reducing severe and fatal complications in 4,241 and 5,966 primary care, working-age patients aged 18-64 years who had asthma or chronic obstructive pulmonary disease during the 1998-1999 and 1999-2000 influenza epidemics in the Netherlands. Patients developing fatal or nonfatal exacerbations of lung disease, pneumonia, congestive heart failure, or myocardial infarction during either epidemic were considered cases. For each case, four age- and sex-matched controls were randomly sampled, and patient records were reviewed. Conditional logistic regression and propensity scores were used to assess vaccine effectiveness after adjustment for confounding factors. In seasons one and two, respectively, 87% (47/54) and 85% (171/202) of the cases and 74% (155/210) and 75% (575/766) of the controls had been vaccinated. After adjustments, vaccination was not associated with reductions in complications (season one: odds ratio = 0.95, 95% confidence interval (CI): 0.26, 3.48; season two: odds ratio = 1.07, 95% CI: 0.59, 1.96; pooled odds ratio = 1.07, 95% CI: 0.63, 1.80). Because influenza vaccination appeared not to be associated with a clinically relevant reduction in severe morbidity, other measures need to be explored. (+info)