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A vaccine candidate for COVID-19 has been identified by researchers from the Oxford Vaccine Group and Oxford's Jenner Institute.
Nasopharyngeal Carriage of Pneumococcus in Children in England up to 10 Years After 13-Valent Pneumococcal Conjugate Vaccine Introduction: Persistence of Serotypes 3 and 19A and Emergence of 7C.
BACKGROUND: Monitoring changes in pharyngeal carriage of pneumococcus in children following 13-valent pneumococcal conjugate vaccine (PCV13) introduction in the United Kingdom in 2010 informs understanding of patterns of invasive pneumococcal disease (IPD) incidence. METHODS: Nasopharyngeal swabs from healthy children vaccinated with PCV13 according to schedule (2, 4, and 12 months) were cultured and serotyped. Results for children aged 13-48 months were compared between 2014-2015 and 2017-2019 and with children aged 6-12 months (2017-2020). Blood was obtained from a subset of children for pneumococcal serotype-specific immunoglobulin G (IgG). RESULTS: Total pneumococcal carriage at 13-48 months was 47.9% (473/988) in 2014-2015 and 51.8% (412/795) in 2017-2019 (P = .10); at age 6-12 months this value was 44.6% (274/615). In 2017-2019, 2.9% (95% confidence interval, 1.8%-4.3%) of children aged 13-48 months carried PCV13 serotypes (mainly 3 [1.5%] and 19A [0.8%]) and >20% carried the additional 20-valent PCV (PCV20) serotypes. Similar proportions of children had IgG ≥0.35 IU/mL for each serotype in 2014-2015 and 2017-2019. Serotype 7C carriage increased significantly (P < .01) between 2014-2015 and 2017-2019. Carriage of PCV20 serotypes 8 and 12F, both major causes of IPD, was rare. CONCLUSIONS: Introduction of PCV20, if licensed for children, could significantly change the composition of pneumococcal serotypes carried in the pharynx of UK children. CLINICAL TRIALS REGISTRATION: NCT03102840.
Equity of the Meningitis B vaccination programme in England, 2016-2018.
In England, the Meningitis B (MenB) vaccine is scheduled at eight and 16 weeks with a booster dose at one year of age and protects children against invasive bacterial meningococcal disease caused by Neisseria meningitidis serogroup B. Coverage of the second dose of MenB vaccine at 12 months was >92% in 2017/18, but this may mask inequalities in coverage in particular population groups. MenB vaccination records for children aged six, 12 and 18 months of age from December 2016 to May 2018 were routinely extracted from GP patient management systems every month in England via a web-based platform for national monitoring of vaccine coverage. We determined the association between ethnicity, deprivation and area of residence, vaccine coverage and drop-out rates (between dose one and dose two), using binomial regression. After adjusting for other factors, ethnic groups with lowest dose one coverage (Black or Black British-Caribbean, White-Any other White background, White-Irish) also had lowest dose two coverage, but in addition, these ethnic groups also had the largest drop-out rates between dose one and dose two. The drop-out rate for Black or Black British-Caribbean children was 5.7 percentage points higher than for White-British children. Vaccine coverage decreased with increasing deprivation quintile, and this was most marked for the booster coverage (6.2 percentage points lower in the most deprived compared to least deprived quintile, p < 0.001). To achieve high coverage for completed courses across all ethnic groups and deprivation quintiles both high initiation rates and a reduction in drop-out rates for ethnic groups with lowest coverage is necessary. A qualitative approach to better understand reasons behind lower coverage and higher drop-out rates in the most underserved ethnic groups is required to develop tailored approaches addressing these inequalities.
A review of the international issues surrounding the availability and demand for diphtheria antitoxin for therapeutic use.
Diphtheria treatment requires early administration of diphtheria antitoxin (DAT), an immunoglobulin preparation that neutralises circulating diphtheria toxin. Here, we review issues relating to the supply and use of DAT and assess its availability by means of an international survey. Results showed that several countries do not currently hold DAT stockpiles due to low prevalence, and hence perceived risk of diphtheria, and/or difficulties in obtaining DAT supplies. The potential for importation of cases into any country exists globally, since diphtheria remains endemic in many regions. It is therefore important that DAT be readily available - particularly since waning diphtheria immunity has been observed among adult populations in countries with good vaccination coverage. Options for diphtheria therapy are discussed.
Immunity to tetanus and diphtheria in the UK in 2009.
INTRODUCTION: This study aimed to estimate the immunity of the UK population to tetanus and diphtheria, including the potential impact of new glycoconjugatate vaccines, and the addition of diphtheria to the school leaver booster in 1994. METHODS: Residual sera (n=2697) collected in England in 2009/10 were selected from 18 age groups and tested for tetanus and diphtheria antibody. Results were standardised by testing a panel of sera (n=150) to enable comparison with a previously (1996) published serosurvey. Data were then standardised to the UK population. RESULTS: In 2009, 83% of the UK population were protected (≥0.1 IU/mL) against tetanus compared to 76% in 1996 (p=0.079), and 75% had at least basic protection against diphtheria (≥0.01 IU/mL) in 2009 compared to 60% in 1996 (p<0.001). Higher antibody levels were observed in those aged 1-3 years in 2009 compared to 1996 for both tetanus and diphtheria. Higher diphtheria immunity was observed in those aged 16-34 years in 2009 compared to 1996 (geometric mean concentration [GMC] 0.15 IU/mL vs. 0.03 IU/mL, p<0.001). Age groups with the largest proportion of susceptible individuals to both tetanus and diphtheria in 2009 were <1 year old (>29% susceptible), 45-69 years (>20% susceptible) and 70+ years (>32% susceptible). Low immunity was observed in those aged 10-11 years (>19% susceptible), between the scheduled preschool and school leaver booster administration. DISCUSSION: The current schedule appears to induce protective levels; increases in the proportions protected/GMCs were observed for the ages receiving vaccinations according to UK policy. Glycoconjugate vaccines appear to have increased immunity, in particular for diphtheria, in preschool age groups. Diphtheria immunity in teenagers and young adults has increased as a result of the addition of diphtheria to the school leaver booster. However, currently older adults remain susceptible, without any further opportunities for immunisations planned according to the present schedule.
Diphtheria in the United Kingdom, 1986-2008: the increasing role of Corynebacterium ulcerans.
Diphtheria is an uncommon disease in the UK due to an effective immunization programme; consequently when cases do arise, there can be delays in diagnosis and case-fatality rates remain high. We reviewed 102 patients with infections caused by toxigenic corynebacteria (an average of four per year) reported in the UK between 1986 and 2008: 42 Corynebacterium diphtheriae, 59 C. ulcerans and one C. pseudotuberculosis, as well as 23 asymptomatic carriers. Five fatalities were reported, all in unvaccinated patients. The major risk factor for C. diphtheriae infection continued to be travel to an endemic country. C. ulcerans infections became more common than C. diphtheriae infections in the UK; they were associated with contact with companion animals. The occurrence of indigenous severe C. ulcerans infections and imported C. diphtheriae cases highlights the need to maintain UK routine vaccination coverage at the 95% level in the UK, as recommended by the World Health Organization.
Inequalities in childhood vaccination timing and completion in London.
The UK primary vaccination course includes vaccination against diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib) and is scheduled at ages four, 8 and 12 weeks, followed by a 'preschool booster' at age three years four months. Vaccine coverage is generally measured at age one, two and five years. In addition to high coverage, vaccination should be timely to maximise population protection. Vaccination histories for 315,381 children born March 2001 to April 2010 were extracted from Child Health Information Systems in nine London health service areas and grouped into first and fifth birthday cohorts. We assessed timeliness of receipt of DTaP/IPV/Hib and drop-out rates by ethnicity, deprivation and area. Most children received their first, second and third doses on time at two, three, and four months. Among children completing by one year and after adjusting for deprivation and health area, compared with White-British children, Somali and Bangladeshi children were less likely to have received three doses of DTaP/IPV/Hib by six months of age (-11% and -5% respectively). Differences in timeliness by deprivation and health area existed, but were smaller. Compared with White-British children, children of Polish, Somali and Caribbean ethnicities were less likely to return for preschool booster, with a drop-out rate at least 7% higher in these groups. Within the fifth birthday cohort, only 2.3% of children who were completely unvaccinated (575/25,095) at age one year were fully vaccinated by age five. Higher proportions of partially vaccinated (one or two doses) children at age one year went on to be fully vaccinated by age five ((836/3213) 26.0% and (3565/6076) 58.7% respectively). These inequalities suggest that tailored approaches may be required to target specific groups with regards to improving vaccine uptake.
What school-level and area-level factors influenced HPV and MenACWY vaccine coverage in England in 2016/2017? An ecological study.
OBJECTIVE: To describe school-level and area-level factors that influence coverage of the school-delivered human papillomavirus (HPV) and meningococcal A, C, W and Y (MenACWY) programmes among adolescents. DESIGN: Ecological study. SETTING AND PARTICIPANTS: Aggregated 2016/2017 data from year 9 pupils were received from 1407 schools for HPV and 1432 schools for MenACWY. The unit of analysis was the school. PRIMARY AND SECONDARY OUTCOME MEASURES: Outcome measures were percentage point (pp) difference in vaccine coverage by schools' religious affiliation, school type, urban/rural, single sex/mixed and region. A subanalysis of mixed-sex, state-funded secondary schools also included deprivation, proportion of population from black and ethnic minorities, and school size. RESULTS: Muslim and Jewish schools had significantly lower coverage than schools of no religious character for HPV (24.0 (95% CI -38.2 to -9.8) and 20.5 (95% CI -30.7 to -10.4) pp lower, respectively) but not for MenACWY. Independent, special schools and pupil referral units had increasingly lower vaccine coverage compared with state-funded secondary schools for both HPV and MenACWY. For both vaccines, coverage was 2 pp higher in rural schools than in urban schools and lowest in London. Compared with mixed schools, HPV coverage was higher in male-only (3.7 pp, 95% CI 0.2 to 7.2) and female-only (4.8 pp, 95% CI 2 to 7.6) schools. In the subanalysis, schools located in least deprived areas had the highest coverage for both vaccines (3.8 (95% CI 0.9 to 6.8) and 10.4 (95% CI 7.0 to 13.8) pp for HPV and MenACWY, respectively), and the smallest schools had the lowest coverage (-10.4 (95% CI -14.1 to -6.8) and -7.9 (95% CI -12 to -3.8) for HPV and MenACWY, respectively). CONCLUSIONS: Tailored approaches are required to improve HPV vaccine coverage in Muslim and Jewish schools. In addition, better ways of reaching pupils in smaller specialist schools are needed.
Oral fluid testing for pertussis, England and wales, june 2007-august 2009.
Existing pertussis surveillance systems tend to underidentify less severe cases among older children and adults. For routine follow-up of notified, nonconfirmed, clinically diagnosed pertussis cases, use of an oral fluid test was pilot tested in England and Wales during June 2007-August 2009. During that period, 1,852 cases of pertussis were confirmed by established laboratory methods and another 591 by oral fluid testing only. Although introduction of serologic testing in 2002 led to the greatest increase in ascertainment of pertussis, oral fluid testing increased laboratory ascertainment by 32% overall; maximal increase (124%) occurred among children 5-9 years of age. Patients whose pertussis was confirmed by oral fluid testing were least likely to be hospitalized, suggesting that milder community cases were being confirmed by this method. Oral fluid testing is an easily administered, noninvasive surveillance tool that could further our understanding of pertussis epidemiology and thereby contribute to decisions on vaccination strategies.
Sociodemographic predictors of variation in coverage of the national shingles vaccination programme in England, 2014/15.
INTRODUCTION: In September 2013, England introduced a shingles vaccination programme to reduce incidence and severity of shingles in the elderly. This study aims to assess variation in vaccine coverage with regards to selected sociodemographic factors to inform activities for improving equity of the programme. METHODS: Eligible 70year-olds were identified from a national vaccine coverage dataset in 2014/15 that includes 95% of GPs in England. NHS England Local Team (LT) and index of multiple deprivation (IMD) scores were assigned to patients based on GP-postcode. Vaccine coverage (%) with 95% confidence intervals (CIs), were calculated overall and by LT, ethnicity and IMD, using binomial regression. RESULTS: Of 502,058 eligible adults, 178,808 (35.6%) had ethnicity recorded. Crude vaccine coverage was 59.5% (95%CI: 59.3-59.7). Coverage was lowest in London (49.6% coverage, 95%CI: 49.0-50.2), and compared to this coverage was significantly higher in all other LTs (+6.3 to +10.4, p<0.001) after adjusting for ethnicity and IMD. Coverage decreased with increasing deprivation and was 8.2% lower in the most deprived (95%CI: 7.3-9.1) compared with the least deprived IMD quintile (64.1% coverage, 95%CI: 63.6-64.6), after adjustment for ethnicity and LT. Compared with White-British (60.7% coverage, 95%CI: 60.5-61.0), other ethnic groups had between 4.0% (Indian) and 21.8% (Mixed: White and Black African) lower coverage. After adjusting for IMD and LT, significantly lower coverage by ethnicity persisted in all groups, except in Mixed: Other, Indian and Bangladeshi compared with White-British. CONCLUSIONS: After taking geography and deprivation into account, shingles vaccine coverage varied by ethnicity. White-British, Indian and Bangladeshi groups had highest coverage; Mixed: White and Black African, and Black-other ethnicities had the lowest. Patients' ethnicity and IMD are predictors of coverage which contribute to, but do not wholly account for, geographical variation coverage. Interventions to address service-related, sociodemographic and ethnic inequalities in shingles vaccine coverage are required.
Screening for Corynebacterium diphtheriae and Corynebacterium ulcerans in patients with upper respiratory tract infections 2007-2008: a multicentre European study.
Diphtheria is now rare in most European countries but, when cases do arise, the case fatality rate is high (5-10%). Because few countries continue to routinely screen for the causative organisms of diphtheria, the extent to which they are circulating amongst different European populations is largely unknown. During 2007-2008, ten European countries each screened between 968 and 8551 throat swabs from patients with upper respiratory tract infections. Six toxigenic strains of Corynebacterium diphtheriae were identified: two from symptomatic patients in Latvia (the country with the highest reported incidence of diphtheria in the European Union) and four from Lithuania (two cases, two carriers); the last reported case of diphtheria in Lithuania was in 2002. Carriage rates of non-toxigenic organisms ranged from 0 (Bulgaria, Finland, Greece, Ireland, Italy) to 4.0 per 1000 (95% CI 2.0-7.1) in Turkey. A total of 28 non-toxigenic strains were identified during the study (26 C. diphtheriae, one Corynebacterium ulcerans, one Corynebacterium pseudotuberculosis). The non-toxigenic C. ulcerans strain was isolated from the UK, the country with the highest reported incidence of cases due to C. ulcerans. Of the eleven ribotypes detected, Cluj was seen most frequently in the non-toxigenic isolates and, amongst toxigenic isolates, the major epidemic clone, Sankt-Petersburg, is still in circulation. Isolation of toxigenic C. diphtheriae and non-toxigenic C. diphtheriae and C. ulcerans in highly-vaccinated populations highlights the need to maintain microbiological surveillance, laboratory expertise and an awareness of these organisms amongst public health specialists, microbiologists and clinicians.
School-based vaccination programmes: An evaluation of school immunisation delivery models in England in 2015/16.
Schools are increasingly being used to deliver vaccines. In 2015/16 three school-based vaccination programmes were delivered to adolescents in England: human papillomavirus (HPV), meningococcal groups A, C, W and Y disease (MenACWY) and tetanus, diphtheria and polio (Td/IPV). We assessed how school delivery models impact vaccine coverage and how a delivery model for one programme may impact another. Routinely collected national data were analysed to ascertain the school grade achieving highest coverage within each one-dose programme and to compare two-dose delivery models (within year vs across years) for the HPV vaccine. We also assessed whether the HPV delivery model was associated with coverage in other programmes. MenACWY and Td/IPV coverage was highest in younger school grades. Overall similar HPV coverage was achieved with both models (86.7% two doses within one year, 85.8% two doses across two years, p = 0.20). High two-dose HPV coverage in 2015/16 was reported in areas that achieved high HPV coverage in 2013/14 when three doses were required. Areas with high three-dose coverage in 2013/14 achieved higher coverage with a within-one-year approach (92.0% vs 85.2%, p < 0.001), whilst areas reporting low coverage in 2013/14 achieved lower but similar coverage in 2015/16 with both models (79.2% vs 80.9% p = 0.29). MenACWY and Td/IPV coverage were higher in areas with high HPV coverage in 2013/14. Among high HPV coverage areas, MenACWY coverage was higher when HPV doses were delivered within year. School-based programmes should be offered as early as feasible and acceptable to optimise coverage. The choice of delivery model for HPV should take into account local performance and provider experience. Single providers may delivery multiple vaccines and the delivery for one programme may affect the performance of other programmes. Providers should consider local circumstances including past and current vaccine coverage and factors influencing coverage when deciding what delivery model to adopt.
Migrant health and infectious diseases in the UK: findings from the last 10 years of surveillance.
BACKGROUND: Migrants account for an increasing proportion of the UK population. They are at risk of acquiring infectious diseases in their country of origin (prior to migration or during return visits), during migration, as well as in their destination country. Migrants can therefore have different risk profiles to the indigenous population. METHODS: UK enhanced surveillance data for TB, HIV, malaria and enteric fever were analysed, with a focus on 2010, for migrant (non-UK born) populations. RESULTS: South Asia was the most common region of birth for TB and enteric fever cases (57 and 80% of migrant cases, respectively). Sub-Saharan Africa was the predominant region of birth for HIV in heterosexuals and malaria cases (80 and 75% of migrant cases, respectively). The majority of cases of TB, HIV in heterosexuals, malaria and enteric fever reported in the UK are migrants. Among UK-born cases, ethnic minorities are disproportionately represented. CONCLUSIONS: This analysis highlights the importance of considering, and improving the recording of, country of birth as a risk factor for infection. Consideration of multiple health risks is of value for migrant patients, and this has implications for the design of improved preventative strategies.
Diphtheria in the postepidemic period, Europe, 2000-2009.
Diphtheria incidence has decreased in Europe since its resurgence in the 1990s, but circulation continues in some countries in eastern Europe, and sporadic cases have been reported elsewhere. Surveillance data from Diphtheria Surveillance Network countries and the World Health Organization European Region for 2000-2009 were analyzed. Latvia reported the highest annual incidence in Europe each year, but the Russian Federation and Ukraine accounted for 83% of all cases. Over the past 10 years, diphtheria incidence has decreased by >95% across the region. Although most deaths occurred in disease-endemic countries, case-fatality rates were highest in countries to which diphtheria is not endemic, where unfamiliarity can lead to delays in diagnosis and treatment. In western Europe, toxigenic Corynebacterium ulcerans has increasingly been identified as the etiologic agent. Reduction in diphtheria incidence over the past 10 years is encouraging, but maintaining high vaccination coverage is essential to prevent indigenous C. ulcerans and reemergence of C. diphtheriae.
Women who experience obstetric haemorrhage are at higher risk of anaemia, in both rich and poor countries.
OBJECTIVES: Anaemia is a potential long-term sequel of obstetric blood loss, but the increased risk of anaemia in women who experience a haemorrhage compared to those who do not has not been quantified. We sought to quantify this risk and explore the duration of increased risk for these women. METHODS: Systematic review of articles published between 1990 and 2009. Data were analysed by high- and low-income country groupings. Prevalence and incidence ratios, and mean haemoglobin levels were compared. RESULTS: Eleven of 822 studies screened were included in the analysis. Most studies showed a higher prevalence or incidence of anaemia in women who had experienced haemorrhage than in those who did not, irrespective of the timing of measurement post-partum. In high-income countries, women who had a haemorrhage were at 5.68 (95% CI 5.04-6.40) times higher risk of post-partum anaemia than women who did not. In low-income countries, the prevalence of anaemia was 1.58 (95% CI 0.96-2.60) times higher in women who had a haemorrhage than in women who did not, although this ratio was greater when the study including mild anaemia in its definition of anaemia was excluded (1.93, 95% CI 1.42-2.62). Population-attributable fractions ranged from 14.9% to 39.6%. Several methodological issues, such as definitions, exclusion criteria and timing of measurements, hindered the comparability of study results. CONCLUSIONS: Women who experience haemorrhage appear to be at increased risk of anaemia for many months after delivery. This important finding could have serious implications for their health care and management.
Density-dependent mortality of the human host in onchocerciasis: relationships between microfilarial load and excess mortality.
BACKGROUND: The parasite Onchocerca volvulus has, until recently, been regarded as the cause of a chronic yet non-fatal condition. Recent analyses, however, have indicated that in addition to blindness, the parasite can also be directly associated with human mortality. Such analyses also suggested that the relationship between microfilarial load and excess mortality might be non-linear. Determining the functional form of such relationship would contribute to quantify the population impact of mass microfilaricidal treatment. METHODOLOGY/PRINCIPAL FINDINGS: Data from the Onchocerciasis Control Programme in West Africa (OCP) collected from 1974 through 2001 were used to determine functional relationships between microfilarial load and excess mortality of the human host. The goodness-of-fit of three candidate functional forms (a (log-) linear model and two saturating functions) were explored and a saturating (log-) sigmoid function was deemed to be statistically the best fit. The excess mortality associated with microfilarial load was also found to be greater in younger hosts. The attributable mortality risk due to onchocerciasis was estimated to be 5.9%. CONCLUSIONS/SIGNIFICANCE: Incorporation of this non-linear functional relationship between microfilarial load and excess mortality into mathematical models for the transmission and control of onchocerciasis will have important implications for our understanding of the population biology of O. volvulus, its impact on human populations, the global burden of disease due to onchocerciasis, and the projected benefits of control programmes in both human and economic terms.
Identifying regional variation in the prevalence of postpartum haemorrhage: a systematic review and meta-analysis.
OBJECTIVE: To provide regional estimates of the prevalence of maternal haemorrhage and explore the effect of methodological differences between studies on any observed regional variation. METHODS: We conducted a systematic review of the prevalence of maternal haemorrhage, defined as blood loss greater than or equal to 1) 500 ml or 2) 1000 ml in the antepartum, intrapartum or postpartum period. We obtained regional estimates of the prevalence of maternal and severe maternal haemorrhage by conducting meta-analyses and used meta-regression to explore potential sources of between-study heterogeneity. FINDINGS: No studies reported the prevalence of antepartum haemorrhage (APH) according to our definitions. The prevalence of postpartum haemorrhage (PPH) (blood loss ≥500 ml) ranged from 7.2% in Oceania to 25.7% in Africa. The prevalence of severe PPH (blood loss ≥1000 ml) was highest in Africa at 5.1% and lowest in Asia at 1.9%. There was strong evidence of between-study heterogeneity in the prevalence of PPH and severe PPH in most regions. Meta-regression analyses suggested that region and method of measurement of blood loss influenced prevalence estimates for both PPH and severe PPH. The regional patterns changed after adjusting for the other predictors of PPH indicating that, compared with European women, Asian women have a lower prevalence of PPH. CONCLUSIONS: We found evidence that Asian women have a very low prevalence of PPH compared with women in Europe. However, more reliable estimates will only be obtained with the standardisation of the measurement of PPH so that the data from different regions are comparable.
Role of PCR in the diagnosis of pertussis infection in infants: 5 years' experience of provision of a same-day real-time PCR service in England and Wales from 2002 to 2007.
As part of an enhanced surveillance programme for pertussis in England and Wales, a real-time PCR service for the detection of Bordetella pertussis was introduced for infants aged
Childhood vaccination coverage by ethnicity within London between 2006/2007 and 2010/2011.
OBJECTIVES: To assess childhood vaccination coverage at first, second and fifth birthdays by ethnicity in London between 2006/2007 and 2010/2011 and identify factors relating to lower coverage. DESIGN: Data concerning receipt of diphtheria-containing vaccines were extracted from child health information systems (CHISs) and sent to the Health Protection Agency. SETTING: Nine London Primary Care Trusts (PCTs). PARTICIPANTS: Records for 315 381 children born April 2001-March 2010. MAIN OUTCOME MEASURES: Receipt of a full primary course of diphtheria-containing vaccines at first and second birthdays, and a primary course and preschool booster at fifth birthday. RESULTS: Consistently good vaccine coverage of the primary course (>88% at first birthday, >89% at second birthday) was achieved across the five largest ethnic groups. Coverage of the preschool booster at fifth birthday was >65% across the five largest ethnic groups. Lowest coverage was observed in smaller ethnic groups. Deprivation was not a strong indicator of coverage overall, and for most ethnic groups there was no relationship between deprivation and coverage. Coverage was significantly lower in children not assigned to a general practitioner practice in the CHIS. CONCLUSIONS: Smaller, less well-established ethnic groups within a PCT may require specific targeting to ensure children are fully immunised and to improve record keeping. Unregistered children need particular attention and may be missed by current scheduling processes in London. In order to monitor the impact of the current National Health Service (NHS) reorganisation on inequalities in access to healthcare data on country of birth, in addition to ethnicity, should be available for analysis.
Effectiveness of the typhoid Vi vaccine in overseas travelers from England.
BACKGROUND: Approximately 500 cases of enteric fever, caused by Salmonella enterica serovar Typhi and Paratyphi, are reported in the UK each year. The majority are associated with travel to the Indian subcontinent. The typhoid Vi vaccine protects against S. Typhi and is available to travelers from their general practice or private clinics. The effectiveness of this vaccine has been assessed previously in endemic regions of the world but not in travelers. METHODS: Data from the enhanced surveillance scheme concerning persons in England aged ≥2 years who traveled from the UK and contracted culture-confirmed enteric fever were used to calculate the effectiveness of the vaccine in travelers. A "case-case" case-control design was used, in which patients with typhoid comprised the "cases" and those with paratyphoid acted as "controls." RESULTS: The overall effectiveness of the vaccine, adjusted for age group, sex, ethnicity, birth in a typhoid-endemic country, and year (of receipt of specimen), was 65% (95% confidence interval 53%-73%). Effectiveness did not vary across subgroups of any of the factors in the model, but there was some evidence of waning effectiveness of the vaccine with increasing time since receipt (trend p = 0.05). CONCLUSIONS: The vaccine has been demonstrated to have a similar effectiveness in travelers as that found in endemic populations. It appears to be protective in all ages, including in young children (aged 2-5 years), a finding not consistently replicated in other studies. However, good hygiene practices are necessary in addition to vaccination to prevent infection. The "case-case" case-control design provides a valuable method of calculating the effectiveness of this vaccine in travelers, given the availability of paratyphoid controls, a population with similar demographics and risk exposures.
The waning of maternal measles antibodies: A multi-country maternal-infant seroprevalence study.
OBJECTIVES: To assess geographical variation in maternal measles antibody levels from birth to nine months of age, to inform recommendations for the timing of the first measles vaccine dose. METHODS: Stored infant serum samples from 11 countries taken at delivery and/or follow-up time points prior to measles vaccination (N=2845) were tested for measles plaque reduction neutralisation (PRNT) and measles, mumps, and rubella immunoglobulin G at a central laboratory. Antibody decay in infants was modelled using linear mixed effects models with participant-level random intercepts and random slopes. Proportions of infants with antibody concentrations above the clinical protection threshold (0.12 IU/mL) were estimated at each age. RESULTS: At birth, most (94%, 519/552) infants had PRNT ≥0.12 IU/mL, but geometric mean concentrations ranged from 0.32 IU/mL (Guatemala) to 1.60 IU/mL (Pakistan). There was no geographical variation in the decay rate of PRNT nor immunoglobulin G. Geometric mean PRNT fell below 0.12 IU/mL between ages 2.5 months (Guatemala) and 6.2 months (Pakistan). At age 6 months, <50% of infants had PRNT ≥0.12 IU/mL in all countries except Pakistan. CONCLUSIONS: Reliance on maternal antibodies for protection until age 9 months or later leaves most infants with insufficient direct protection against measles infection between ages 6-9 months.