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Live vaccines including BCG and measles may have non-targeted beneficial effects on childhood survival in areas with high mortality. The authors therefore undertook a survey of vaccinia scars to evaluate subsequent mortality. Based on a population census, a cohort of 1893 adults in urban Guinea-Bissau was examined in 1998 and followed until 2002. All cause mortality, excluding accidents. The median age of vaccinia vaccinations had been 16-18 years. Adults with a vaccinia scar had a mortality ratio (MR) of 0.60 (0.41-0.87) compared to those without any scar. The effect was stronger for women. Mortality decreased with each additional vaccinia scar (MR=0.73 (0.56-0.95)). Among 502 individuals with information on HIV infection, the age-adjusted HIV-2 prevalence was 2.45 (1.06-5.65) for those with a vaccinia scar. Control for district, ethnic group, schooling, place of birth, quality of housing and HIV status had little effect on the estimate. Since vaccinia and BCG scars could have been confused, mortality for adults with vaccinia and/or BCG scar was compared to those without, the MR being 0.61 (0.41-0.89). Known cultural or socio-economic factors possibly associated with access to vaccination had no influence on the mortality ratio for having a vaccinia scar. Hence, vaccinia vaccination may have a prolonged beneficial effect on adult survival.

The sequence of routine immunisations may be important for childhood mortality. Three doses of diphtheria–tetanus–pertussis vaccine (DTP) should be given at 6, 10, and 14 weeks and measles vaccine (MV) at 9 months of age. The sequence is not always respected. We examined in-hospital mortality of children having received DTP with or after measles vaccine. The only paediatric ward in Bissau, Guinea-Bissau. Children hospitalised during two periods in 1990–1996 and 2001–2002 who had received MV prior to hospitalisation. The all-cause case fatality at the hospital for children aged 6–17 months. The case fatality was increased for children who had received DTP with or after measles vaccine compared with children who had received measles vaccine as the most recent vaccine, the ratio being 2.53 (1.37–4.67) and 1.77 (0.92–3.41) in the two periods, respectively. The combined estimate was 2.10 (1.34–3.28). These results were not explained by differences in nutritional status, number of doses of DTP or discharge policy. Administration of DTP with, or after MV, may reduce the beneficial effect of MV.

Oral polio vaccine (OPV) and diphtheria–tetanus–pertussis (DTP) vaccines are given simultaneously in routine immunisation programmes in developing countries. It is therefore difficult to determine the separate effects of these vaccines on survival. We used the shortage of DTP vaccine in Bissau to examine the impact of OPV on the case fatality at the paediatric ward in Bissau. For 719 children less than 5 years of age whose vaccination card had been seen at admission and who had not yet received measles vaccine, having received OPV only was associated with a case fatality of 6% compared with 15% for children having received combined DTP and OPV vaccinations, the case fatality ratio (CFR) being 0.29 (95% confidence interval (CI) 0.11–0.77). Even if children fleeing the hospital were assumed to have died shortly after leaving the hospital, the case fatality would still be lower for children having received OPV only (CFR=0.41 (95% CI 0.20–0.81)). The tendency was similar for children hospitalised with pneumonia, diarrhoea, and presumptive malaria. Control for background factors had no impact on the estimate. In areas with high mortality, OPV administered alone may have non-specific beneficial effects or DTP may have a negative effect for children who had received both DTP and OPV.

Live vaccines including BCG and measles may have non-targeted beneficial effects on childhood survival in areas with high mortality. The authors therefore undertook a survey of vaccinia scars to evaluate subsequent mortality. Based on a population census, a cohort of 1893 adults in urban Guinea-Bissau was examined in 1998 and followed until 2002. All cause mortality, excluding accidents. The median age of vaccinia vaccinations had been 16–18 years. Adults with a vaccinia scar had a mortality ratio (MR) of 0.60 (0.41–0.87) compared to those without any scar. The effect was stronger for women. Mortality decreased with each additional vaccinia scar (MR = 0.73 (0.56–0.95)). Among 502 individuals with information on HIV infection, the age-adjusted HIV-2 prevalence was 2.45 (1.06–5.65) for those with a vaccinia scar. Control for district, ethnic group, schooling, place of birth, quality of housing and HIV status had little effect on the estimate. Since vaccinia and BCG scars could have been confused, mortality for adults with vaccinia and/or BCG scar was compared to those without, the MR being 0.61 (0.41–0.89). Known cultural or socio-economic factors possibly associated with access to vaccination had no influence on the mortality ratio for having a vaccinia scar. Hence, vaccinia vaccination may have a prolonged beneficial effect on adult survival.

•MMR vaccination is given to protect against measles, mumps and rubella.•RSV is an important cause of acute lower respiratory infections in young children.•MMR vaccination was associated with 22% lower rate of RSV hospital contacts.•MMR vaccination may reduce the rate or severity of RSV infection. The live measles vaccine has been associated with lower non-measles mortality and admissions in low-income countries. The live measles–mumps–rubella vaccine has also been associated with lower rate of admissions with any type of infection in Danish children; the association was strongest for admissions with lower respiratory infections. To examine whether measles, mumps, and rubella (MMR) vaccination was associated with reduced rate of hospital contact related to respiratory syncytial virus (RSV) in a high-income country. Nationwide cohort study of laboratory-confirmed RSV hospital contacts at age 14–23 months in all children born in Denmark 1997–2002 who had already received the vaccine against diphtheria, tetanus, pertussis (acellular), polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) at the recommended ages of 3, 5, and 12 months. The study included 888 RSV hospital contacts in 128,588 person years of follow up (rate 6.8/1000 person years). Having MMR as the most recent vaccine was associated with a reduced rate of RSV hospital contacts compared with having DTaP-IPV-Hib as the most recent vaccine (Incidence rate ratio (IRR), 0.75; 95% confidence interval (CI), 0.63–0.89). After adjustment for potential confounders including exact age in days the IRR was 0.78 (95% CI, 0.66–0.93). The adjusted IRR was 0.74 (95% CI, 0.60–0.92) in males and 0.84 (95% CI, 0.66–1.06) in females (P Interaction, 0.42). There was no association in the first month after MMR vaccination (adjusted IRR, 0.97; 95% CI, 0.76–1.24) but the adjusted IRR was 0.70 (95% CI, 0.58–0.85) from one month after MMR vaccination. MMR vaccination was associated with reduced rate of hospital contacts related to laboratory-confirmed RSV infection. Further research on the association between MMR vaccination and other unrelated pathogens are warranted.

•Nationwide retrospective cohort study of Danish children aged 15months to 4years.•Comparison of the live MMR+the inactivated DTaP-IPV-Hib vaccine vs MMR alone.•27% higher rate of admissions for lower respiratory infections for MMR+DTaP-IPV-Hib.•No significant association with admissions for other types of infections.•Adjustment for a long range of potential confounders including exact age. In Denmark, live measles, mumps, and rubella vaccine (MMR) is associated with a reduced risk of infectious disease admissions, particularly for lower respiratory tract infections. In low-income countries, simultaneous vaccination (i.e. vaccination at the same visit) with live and inactivated vaccines may increase child mortality compared with the live vaccine alone. We examined the hypothesis that simultaneous administration of MMR and the inactivated DTaP-IPV-Hib vaccine compared with MMR alone is associated with higher incidence of infectious disease admissions. Nationwide, retrospective, register based cohort study of 520,859 children born in Denmark 1997–2006, who were followed from 15months to 4years of age. Incidence rate ratios (IRRs) of hospital admissions were estimated by Cox regression and adjusted for background factors including exact age. By 2years of age, 4965 children had simultaneous MMR and DTaP-IPV-Hib as their most recent vaccination. Compared with MMR alone, simultaneous administration was associated with a higher rate of lower respiratory tract infections (adjusted incidence rate ratio (IRR), 1.27; 95% confidence interval (CI), 1.13–1.42). There was no effect on other infections. Overall, simultaneous administration was associated with a 7% (95% CI, 0–15%) increase in infectious disease admissions. Simultaneous administration of MMR and DTaP-IPV-Hib compared with MMR alone may increase the rate of hospital admissions related to lower respiratory tract infections. These findings require replication in other high-income settings.

Vaccines have non-specific effects (NSE) on subsequent morbidity and mortality from non-vaccine related infectious diseases. Thus NSE refers to any effect that cannot be accounted for by the induction of immunity against the vaccine-targeted disease. These effects are sex-differential, generally being more pronounced in females than males. Furthermore, the NSE are substantial causing greater than fifty percent changes in all cause mortality in certain settings, yet have never been systematically tested despite the fact that millions of children receive vaccines each year. As we strive to eliminate infectious diseases through vaccination programmes, the relative impact of NSE of vaccines on mortality is likely to increase, raising important questions regarding the future of certain vaccine schedules. A diverse group of scientists met in Copenhagen to discuss non-specific and sex-differential effects of vaccination, and explore plausible biological explanations. Herein we describe the contents of the meeting and the establishment of the ‘Optimmunize’ network aimed at raising awareness of this important issue among the wider scientific community.