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Pneumo 23 degrees , like the pneumococcal vaccines tested in randomised comparative trials, may slightly reduce the incidence of pneumococcal pneumonia in subjects with no particular risk factors, but fails to alter the overall incidence of pneumonia or its related mortality. In subjects at high risk of infection, pneumococcal vaccines have not been proven clinically effective in well-conducted trials. According to available retrospective studies Pneumo 23 degrees may, at best, slightly reduce the risk of severe pneumococcal infection. It has, however, no demonstrated effect on mortality and does not protect against pneumococci with diminished sensitivity to penicillin.

Clinical evaluation of a new vaccine should be based on information about the epidemiology and pathogenesis of the infection to be prevented, the protective immunity to this infection, and the immunological properties of the vaccine to be evaluated. In this review we describe one approach to evaluate a new vaccine, using our experience with pneumococcal conjugates as an example. Information on the epidemiology, pathogenesis and host responses was collected mainly during 1987-1992, improvement in diagnostic methods was carried out during 1990-1995, and the immunogenicity of vaccine candidates was tested during 1992-1995. Based on these factors, a randomized, controlled, blinded efficacy trial of two pneumococcal conjugate vaccines against acute otitis media was started in Finland in 1995. Enrolment of 2,497 infants has now been completed by April 1997, and the follow-up phase will continue until 1999.

Background: Even though the efficacy of pneumococcal vaccine against invasive pneumococcal infections and other closely related infections has been established, its use in the United States is only one quarter of that of influenza vaccine. The simultaneous administration of the two vaccines could be expected to raise the coverage of pneumococcal vaccination to a considerable degree. There is a paucity of data regarding the reactions associated with the simultaneous administration of pneumococcal and influenza vaccines., Methods: All persons aged 65 years or older living in 29 administrative districts in Northern Finland were offered influenza vaccine alone or influenza and pneumococcal vaccines. A total of 9336 persons (49.6% of the target population) accepted vaccination: 4581 persons born in odd years received influenza vaccine, and 4755 persons born in even years received influenza and pneumococcal vaccines. Local reactions were recorded in a diary by vaccines on the day of vaccination and for 4 days afterward according to the following scale: no reaction, mild reaction, strong reaction, and disabling reaction. The participants who felt feverish were asked to measure and record their temperature. Ninety-three percent of those vaccinated returned the diary., Results: No serious reactions were observed. The incidence of local reactions was 284 per 1000 vaccinations in the influenza-vaccinated group and 441 per 1000 vaccinations in the influenza-pneumococcal-vaccinated group, a difference of 157 (95% confidence interval, 137 to 176), and that of fever (temperature, at least 37.5 degrees C) was 10 and 24 per 1000, respectively, for a difference of 14 (95% confidence interval, 9 to 19). The frequency of local reactions decreased with advancing age., Conclusion: Because the adverse reactions to the pneumococcal and influenza vaccines when given together were mild, we conclude that the simultaneous administration of the two vaccines to the elderly population, irrespective of age, is safe.

Purpose: To determine the clinical effectiveness of Haemophilus influenzae type b (Hib) vaccines. STUDY IDENTIFICATION AND SELECTION: Computerized searches of MEDLINE, EMBASE and SCISEARCH databases were performed, and the reference list of each retrieved article was reviewed. Two prospective clinical trials of Hib polyribosyl ribitol phosphate conjugated with diphtheria toxoid (PRP-D) were identified. In addition, one cohort study of the PRP-D vaccine, two trials of the PRP vaccine, five case-control studies of the PRP vaccine and 10 randomized controlled trials of the immunogenicity of the PRP-D vaccine were identified., Data Extraction: Study quality was assessed and descriptive information concerning the study populations, the interventions and the outcome measurements was extracted., Results: The difference in the effectiveness of the PRP-D vaccine between the prospective trials, in which a three-dose schedule had been used beginning at 2 to 3 months of age, was clinically important (37% v. 83%) but not statistically significant. The PRP vaccine, which induces lower antibody responses than the PRP-D vaccine does, was clinically effective only in a subgroup of one prospective trial; 90% effectiveness was reported among children 18 to 60 months of age., Conclusions: Hib vaccine appears to be less effective in high-risk populations. None the less, because of the large variation in baseline risk, the number of children who would have to be vaccinated to prevent one case of invasive Hib disease is substantially less for high-risk than for low-risk populations. The vaccination of children at high risk, such as native children, with the PRP-D vaccine using a four-dose schedule (at 2, 4, 6 and 14 months of age) seems warranted. The currently available evidence does not strongly support a policy of universal vaccination with either a one-dose or a four-dose schedule.

In 1976 routine vaccination against Neisseria meningitidis serogroups A and C was started in the Finnish Armed Forces. A case of fulminant, complicated pneumonia caused by group-Y meningococcus in a vaccinated recruit, prompted a study of the distribution of the meningococcal groups isolated from the recruits in the same unit. 14 (46%) of the 31 isolates from 84 recruits were group Y. Group-Y meningococcus was rarely isolated from unvaccinated controls. These results suggest that widespread vaccination against serogroups A and C may have led to an increase in the frequency of meningococcus group Y.

Stimulated by questions raised on potential differences between the Haemophilus influenzae type b capsular polysaccharide (PRP) vaccines on the market and the applicability of the efficacy data of a similar PRP vaccine obtained in a large field study in 1974 in Finland, we wished to compare the immunogenicity of all these preparations in 24-month-old Finnish children. In our study 137 children received the now recommended 25-micrograms dose of 1 of 4 H. influenzae type b PRP vaccines currently available, and an additional 86 children received half this dose corresponding to the 12.7 micrograms used in 1974. Anti-PRP antibodies were measured in blood samples taken before and 4 weeks after vaccination by the same radioimmunoassay and in the same laboratory as in 1974. The vaccines were equally immunogenic. Furthermore the now recommended dose of 25 micrograms did not give results (geometric mean concentrations, 2.38 to 3.45 micrograms/ml) differing from those after a 12.5-micrograms (2.01- to 3.45-micrograms/ml) dose which was used in 1974. Antibody concentrations of 0.15 and 1.0 micrograms/ml were achieved in 91 to 95 and 66 to 84% of the children, respectively. The corresponding values after 1974 vaccinations were 3.53 micrograms/ml and 100 and 82% of children, respectively. The percentage of those responding with concentrations greater than or equal to 1 microgram/ml was somewhat higher in these Finnish children than reported for children of the same age receiving the same vaccine lots in the United States. Adverse reactions were mild or moderate and transient.

We performed field trials in the course of an epidemic in Finland to learn whether Group A memingococcal capsular polysaccharide vaccine protects infants and young children from meningitis. The first trial involved 130,178 children between the ages of three months and five years; 49,295 children received the vaccine, 48,977 received a control Haemophilus influenzae Type b polysaccharide vaccine, and 31.906 remained unvaccinated. No cases of meningitis or sepsis caused by Group A meningococci were seen in the first year of observation among the children vaccinated with meningococcal vaccine whereas six occurred among those vaccinated with the H. influenzae vaccine and 13 among those not vaccinated. In the second trial 21,007 children of the same ages received the meningococcal vaccine. No cases caused by Group A occurred among those vaccinated, although five to seven would have been expected within the year. Meningococcal Group A vaccine appears efficacious in young infants and children.

Meningococcal group A polysaccharide vaccine was used in children 3 months to 5 years of age in the winter 1974-75 during an epidemic caused by sulphanamide-resistant group A meningococci. In 3 provinces, the vaccine was offered on a double-blind basis, using Haemophilus influenzae type b polysaccaride vaccine as control. Approximately 100 000 children were vaccinated with either one of the vaccines. In the Kymi province, approximately 22 000 children representing 90% of the child population of this age received the meningococcus vacine. Infants below 18 months received a booster dose of vaccine 3 months after the first dose. The meningococcus vaccine caused local symptoms in 71%, mild systemic reactions in 37%, and high fever (38.5 degrees C or more) in 1.8% The haemophilus vaccine produced fewer side effects. No clinical infections caused by group A meningococci were reported in the first 6 months after vaccination among those who had received the meningococcal vaccine. At the same time, group A cases continued to appear in other age groups and other areas of the country.

A recently developed Haemophilus influenzae type b capsular polysaccharide vaccine was given to 48,977 children 3 months to 5 years of age; an equal number of children receiving group A meningococcal vaccine served as controls. The protection as well as serum antibody response was strongly age-dependent. Among children who had received the H. influenzae type b vaccine when 18 months of age or older, there were no cases of bacteremic disease caused by H. influenzae type b in the first year after vaccination. At the same time 11 such cases were seen in the control group of the same age, a highly significant difference. In the second year after vaccination two cases occurred in the H. influenzae type b-vaccinated group, five in the meningococcal-group A vaccinated group. No protection was seen among children who had been younger than 18 months when vaccinated, even if they received a booster dose of the vaccine. The serum antibody response to the H. influenzae type b polysaccharide, measured by radioimmunoassay, was poor in children below 18 months of age and good in those above it. No effect of the vaccine could be seen on the nasopharyngeal carriage of H. influenzae type b, which was approximately 6% in this age group. Adverse effects of the vaccine were mild.