Risk factors for SARS-CoV-2 infection: a test-negative case-control study with additional population controls in Norway

OBJECTIVES

This study aims to assess risk factors for SARS-CoV-2 infection by combined design; first comparing positive cases to negative controls as determined by PCR testing and then comparing these two groups to an additional prepandemic population control group.

DESIGN AND SETTING

Test-negative design (TND), multicentre case-control study with additional population controls in South-Eastern Norway.

PARTICIPANTS

Adults who underwent SARS-CoV-2 PCR testing between February and December 2020. PCR-positive cases, PCR-negative controls and additional age-matched population controls.

PRIMARY OUTCOME MEASURES

The associations between various risk factors based on self- reported questionnaire and SARS-CoV-2 infection comparing PCR-positive cases and PCR-negative controls. Using subgroup analysis, the risk factors for both PCR-positive and PCR-negative participants were compared with a population control group.

RESULTS

In total, 400 PCR-positive cases, 719 PCR-negative controls and 14 509 population controls were included. Male sex was associated with the risk of SARS-CoV-2 infection only in the TND study (OR 1.9, 95% CI 1.4 to 2.6), but not when PCR-positive cases were compared with population controls (OR 1.2, 95% CI 0.9. to 1.5). Some factors were positively (asthma, wood heating) or negatively (hypertension) associated with SARS-CoV-2 infection when PCR-positive cases were compared with population controls, but lacked convincing association in the TND study. Smoking was negatively associated with the risk of SARS-CoV-2 infection in both analyses (OR 0.5, 95% CI 0.3 to 0.8 and OR 0.6, 95% CI 0.4 to 0.8).

CONCLUSIONS

Male sex was a possible risk factor for SARS-CoV-2 infection only in the TND study, whereas smoking was negatively associated with SARS-CoV-2 infection in both the TND study and when using population controls. Several factors were associated with SARS-CoV-2 infection when PCR-positive cases were compared with population controls, but not in the TND study, highlighting the strength of combining case-control study designs during the pandemic.

Hypogammaglobulinemia and Risk of Exacerbation and Mortality in Patients with COPD

Introduction

Chronic obstructive pulmonary disease (COPD) may, in some patients, be characterized by recurring acute exacerbations. Often these exacerbations are associated with airway infections. As immunoglobulins (Ig) are important parts of the immune defence against airway infections, the aim of this study was to relate the levels of circulating immunoglobulins to clinical features in unselected patients with COPD included in a Norwegian multicenter study.

Methods

Clinical and biological data, including circulating levels of immunoglobulins, were assessed in 262 prospectively included patients with COPD GOLD stage II-IV at five hospitals in south-eastern Norway. A revisit was done after one year, and survival was assessed after five years. Clinical features and survival of those with immunoglobulin levels below reference values were compared to those with normal levels.

Results

In total, 11.5% of all COPD patients and 18.5% of those with GOLD stage IV had IgG concentrations below reference values. These patients were more likely to use inhaled or oral steroids, had lower BMI, and lower FEV1%. Moreover, they had significantly more COPD-related hospital admissions (2.8 vs 0.6), number of prednisolone courses (3.9 vs 1.2), and antibiotic treatments (3.7 vs 1.5) in the preceding year. Importantly, hypogammaglobulinemia was significantly associated with reduced survival in a log-rank analysis. In multivariate regression analysis, we found that the higher risk for acute exacerbations in these patients was independent of other risk factors and was associated with impaired survival.

Conclusion

In conclusion, our study suggests that hypogammaglobulinemia may be involved in poor outcome in COPD and may thus be a feasible therapeutic target for interventional studies in COPD.

Changes in pneumococcal carriage prevalence and factors associated with carriage in Norwegian children, four years after introduction of PCV13

Background

Streptococcus pneumoniae carriage is often asymptomatic but can cause invasive pneumococcal disease. Pneumococcal carriage is a prerequisite for disease, with children as main reservoir and transmitters. Childhood carriage can therefore be used to determine which serotypes circulate in the population and which may cause disease in the non-vaccinated population. In 2006, a pneumococcal conjugate vaccine (PCV7) was introduced into the Norwegian Childhood Immunisation Programme, which was replaced by the more valent PCV13 in 2011. We investigated changes in pneumococcal carriage prevalence 4 years after switching to PCV13 compared to three previous surveys, and analysed factors associated with carriage in children.

Methods

We conducted a cross-sectional study in Norway, autumn 2015, among children attending day-care centres. We collected questionnaire data and nasopharyngeal swabs to identify pneumococcal serotypes. We compared the carriage prevalence in 2015 with surveys conducted in the same setting performed before widespread vaccination (2006; n = 610), 2 years after PCV7 introduction (2008; n = 600), and 2 years after switching to PCV13 (2013; n = 874). Using multilevel logistic regression we determined the association between pneumococcal carriage and previously associated factors.

Results

In 2015, 896 children participated, with age ranging from 8 to 80 months. The overall carriage prevalence was 48/100 children [95%CI 44–53] in 2015, 38% [29–46] lower than in 2006 pre-PCV7, and 23% [12–32] lower than in 2013, 2 years after switching to PCV13. The PCV13 carriage prevalence was 2.8/100 children [1.9–4.2] in 2015. Increasing age (p < 0.001), recent antimicrobial use (odds ratio = 0.42 [0.21–0.57]) and being vaccinated (odds ratio = 0.37 [0.29–0.47]) were negatively associated with carriage.

Conclusions

Our study showed a continued decrease in overall pneumococcal carriage, mainly fuelled by the decline in vaccine serotypes after vaccine introduction. Childhood vaccination with PCV13 should be continued to keep low PCV13 carriage, transmission and disease. Furthermore, the low prevalence of PCV13-type carriage in children endorse the choice of not recommending PCV13 in addition to the 23-valent pneumococcal polysaccharide vaccine to most medical risk groups in Norway, as little disease caused by these serotypes can be expected.

Response to third rubella vaccine dose

Limited data exist on the immunogenicity of a third dose of the measles, mumps, and rubella vaccine (MMR). In this study, our aim was to evaluate the long-term rubella immunogenicity afforded by two childhood MMR doses of the Norwegian vaccination program in a cohort of conscripts and to determine the effect of an additional dose of MMR vaccine, in order to inform vaccination policy. Blood samples from Norwegian conscripts (n = 495) taken both before and eight months after administration of a dose of MMR vaccine were tested using an enzyme immunoassay to measure anti-rubella IgG. Concentrations <5 IU/mL were regarded as negative, 5.0-9.9 IU/mL as equivocal, and ≥10 IU/mL as positive. Overall, the seropositivity before vaccination was 84.6%, and 99.0% of the conscripts had anti-rubella IgG concentrations ≥5 IU/mL. The seropositivity after vaccination was 94.5%, and 99.8% of the conscripts had antibody concentrations ≥5 IU/mL. The geometrical mean IgG concentrations increased from 21.4 IU/mL before vaccination to 28.9 IU/mL after. Four out of five conscripts, with seronegative concentrations before administrations of an additional MMR dose, had equivocal or seropositive results following vaccination. The cohort of young adults in Norway, which was eligible for two childhood MMR doses, was protected against rubella, and efforts should be made to maintain high vaccine coverage to ensure immunity in the future. A third dose of MMR administered in early adulthood led to an increase in the antibody concentration in our cohort and seroconversion for the majority of seronegative persons.

In vitro and in vivo comparison of transport media for detecting nasopharyngeal carriage of Streptococcus pneumoniae

Background

As a standard method for pneumococcal carriage studies, the World Health Organization recommends nasopharyngeal swabs be transported and stored at cool temperatures in a medium containing skim-milk, tryptone, glucose and glycerol (STGG). An enrichment broth used for transport at room temperature in three carriage studies performed in Norway may have a higher sensitivity than STGG. We therefore compared the media in vitro and in vivo.

Methods

For the in vitro component, three strains (serotype 4, 19F and 3) were suspended in STGG and enrichment broth. Recovery was compared using latex agglutination, quantification of bacterial loads by real-time PCR of the lytA gene, and counting colonies from incubated plates. For the in vivo comparison, paired swabs were obtained from 100 children and transported in STGG at cool temperatures or in enrichment broth at room temperature. Carriage was identified by latex agglutination and confirmed by Quellung reaction.

Results

In vitro, the cycle threshold values obtained by PCR did not differ between the two media (p = 0.853) and no clear difference in colony counts was apparent after incubation (p = 0.593). In vivo, pneumococci were recovered in 46% of swabs transported in STGG and 51% of those transported in enrichment broth (Kappa statistic 0.90, p = 0.063).

Discussion

Overall, no statistical differences in sensitivity were found between STGG and enrichment broth. Nevertheless, some serotype differences were observed and STGG appeared slightly less sensitive than enrichment broth for detection of nasopharyngeal carriage of pneumococci by culturing. We recommend the continued use of STGG for transport and storage of nasopharyngeal swabs in pneumococcal carriage studies for the benefit of comparability between studies and settings, including more resource-limited settings.

Geographical differences in seroprevalence of Borrelia burgdorferi antibodies in Norway, 2011-2013

Detection of specific antibodies against Borrelia burgdorferi sensu lato is a useful aid for the diagnosis of Lyme borreliosis. However, antibodies are present in the general population. The seroprevalence increase with age, and varies according to the prevalence of infected ticks. We performed a seroprevalence study of IgM and IgG antibody reactivity against B. burgdorferi sensu lato in Norway by age-groups and geography, in order to provide a reference set of seroprevalence to inform the interpretation of positive test results. We used two commercially available enzyme immuno assays (EIA) and a multiplexed bead assay to detect Borrelia IgG antibodies in a convenience sample of 3057 sera collected from clinical chemistry laboratories in 10 of 19 counties in Norway between December 2011 and January 2013. We estimated seroprevalence by age and county by a logistic regression model. IgM antibodies were detected by two commercially available EIAs and a multiplexed bead assay. The overall seroprevalence of Borrelia IgG was 4.0% (95% CI: 2.4-6.6%) and 4.2% (2.6-6.8%) by the two EIAs, respectively. The seroprevalence increased by age, and by geography from north to south. The IgG assays showed a good agreement for positive test results. All sera positive for IgG in the multiplexed bead assay reacted with the VlsE antigen, and also had high antibody levels by EIA. The Borrelia seroprevalence varied by geography and increased by age. The results indicate regional differences in pre-test probabilities for positive test results, and can inform the interpretation of laboratory results.

Tetanus after a minor injury leading to death in a previously non-immunized, elderly, Norwegian woman

Tetanus vaccination is part of the Norwegian childhood vaccination program. An elderly woman injured her arm and leg after a minor fall on her outdoor stairs. Two weeks later she presented with trismus. This developed into tetanic spasms, obstructed airways and the need for a tracheostomy. She died 14 days later due to pneumonia and multi-organ failure. ELISA for tetanus toxoid IgG was negative, probably because the patient was born before the introduction of tetanus vaccination in the Norwegian childhood vaccination program. Lack of adherence to the vaccination programs should be considered in patients presenting with symptoms resembling diseases they normally would be protected from. Although the patient presented with typical symptoms the diagnosis was not suspected initially, probably due to the rareness of this disease in Norway.

Vaccines against meningococcal serogroup B disease containing outer membrane vesicles (OMV): lessons from past programs and implications for the future

The utility of wild-type outer membrane vesicle (wtOMV) vaccines against serogroup B (MenB) meningococcal disease has been explored since the 1970s. Public health interventions in Cuba, Norway and New Zealand have demonstrated that these protein-based vaccines can prevent MenB disease. Data from large clinical studies and retrospective statistical analyses in New Zealand give effectiveness estimates of at least 70%. A consistent pattern of moderately reactogenic and safe vaccines has been seen with the use of approximately 60 million doses of three different wtOMV vaccine formulations. The key limitation of conventional wtOMV vaccines is their lack of broad protective activity against the large diversity of MenB strains circulating globally. The public health intervention in New Zealand (between 2004–2008) when MeNZB was used to control a clonal MenB epidemic, provided a number of new insights regarding international and public-private collaboration, vaccine safety surveillance, vaccine effectiveness estimates and communication to the public. The experience with wtOMV vaccines also provide important information for the next generation of MenB vaccines designed to give more comprehensive protection against multiple strains.

Pre-natal exposure to perfluoroalkyl substances may be associated with altered vaccine antibody levels and immune-related health outcomes in early childhood

Perfluoroalkyl substances (PFAS) are suggested to have immunosuppressive effects; exposure in utero and in the first years of life is of special concern as fetuses and small children are highly vulnerable to toxicant exposure. The objective of this study was to investigate the effect of pre-natal exposure to PFAS on responses to pediatric vaccines and immune-related health outcomes in children up to 3 years of age. In the prospective birth-cohort BraMat, a sub-cohort of the Norwegian Mother and Child Cohort Study (MoBa), pregnant women from Oslo and Akershus, Norway, were recruited during 2007-2008. Three annual questionnaire-based follow-ups were performed. Blood samples were collected from the mothers at the time of delivery and from the children at the age of 3 years. As a measure of pre-natal exposure to PFAS, the concentrations of perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) were determined in maternal blood from 99 BraMat participants. Main outcome measures were anti-vaccine antibody levels, common infectious diseases and allergy- and asthma-related health outcomes in the children up to the age of 3 years. There was an inverse association between the level of anti-rubella antibodies in the children's serum at age 3 years and the concentrations of the four PFAS. Furthermore, there was a positive association between the maternal concentrations of PFOA and PFNA and the number of episodes of common cold for the children, and between PFOA and PFHxS and the number of episodes of gastroenteritis. No associations were found between maternal PFAS concentrations and the allergy- and asthma-related health outcomes investigated. The results indicate that pre-natal exposure to PFAS may be associated with immunosuppression in early childhood.

Preserved splenic function after angioembolisation of high grade injury

BACKGROUND

After introducing splenic artery embolisation (SAE) in the institutional treatment protocol for splenic injury, we wanted to evaluate the effects of SAE on splenic function and assess the need for immunisation in SAE treated patients.

METHODS

15 SAE patients and 14 splenectomised (SPL) patients were included and 29 healthy blood donors volunteered as controls. Clinical examination, medical history, general blood counts, immunoglobulin quantifications and flowcytometric analysis of lymphocyte phenotypes were performed. Peripheral blood smears from all patients and controls were examined for Howell-Jolly (H-J) bodies. Abdominal doppler, gray scale and contrast enhanced ultrasound (CEUS) were performed on all the SAE patients.

RESULTS

Leukocyte and platelet counts were elevated in both SAE and SPL individuals compared to controls. The proportion of memory B-lymphocytes did not differ significantly from controls in either group. In the SAE group total IgA, IgM and IgG levels as well as pneumococcal serotype specific IgG and IgM antibody levels did not differ from the control group. In the SPL group total IgA and IgG Pneumovax(®) (PPV23) antibody levels were significantly increased, and 5 of 12 pneumococcal serotype specific IgGs and IgMs were significantly elevated. H-J bodies were only detected in the SPL group. CEUS confirmed normal sized and well perfused spleens in all SAE patients.

CONCLUSION

In our study non-operative management (NOM) of high grade splenic injuries including SAE, was followed by an increase in total leukocyte and platelet counts. Normal levels of immunoglobulins and memory B cells, absence of H-J bodies and preserved splenic size and intraparenchymal blood flow suggest that SAE has only minor impact on splenic function and that immunisation probably is unnecessary.

Pherotypes of pneumococcal strains co-existing in healthy children

Genetic diversity in the species Streptococcus pneumoniae is mainly driven by horizontal gene transfer. S. pneumoniae is naturally competent for transformation. Competence is induced by a pheromone termed competence stimulating peptide (CSP) by a quorum-sensing mechanism. Two CSP pherotypes predominate amongst clinical isolates of S. pneumoniae, CSP-1 and CSP-2, with ability to trigger competence in bacteria of the homologue pherotype. Opposing theories on the effect of pherotypes on speciation have been proposed, either as a barrier for intra-pherotype gene transfer, or as a mechanism for fratricide resulting in lysis of non-competent bacterial cells. The aim of the present study was to determine pherotype distribution in strains of S. pneumococci isolated from the nasopharynges of healthy children. We sequenced the locus encoding CSP, comC, in sets of strains obtained from children colonised by multiple pneumococcal strains simultaneously. The impact of pherotype on co-colonisation was determined by comparing the observed distribution of pherotypes in co-colonising strains with the estimated pair-wise probability based on the overall pherotype distribution in the sample set. Five distinct comC alleles were identified, encoding CSP belonging to the two dominating pherotypes, CSP-1 (62.7%) and CSP-2 (37.3%). The observed distribution of pherotypes in sets of co-colonising pneumococcal strains did not differ from the probability estimate. Thus, co-colonisation of S. pneumoniae in healthy children is not restricted by pherotype.

Streptococcus pyogenes isolates causing severe infections in Norway in 2006 to 2007: emm types, multilocus sequence types, and superantigen profiles

To investigate the epidemiological patterns and genetic characteristics of disease caused by group A Streptococcus (GAS), all available isolates from invasive cases in Norway during 2006 to 2007 (262 isolates) were subjected to antimicrobial susceptibility testing, T serotyping, emm typing, and multilocus sequence typing and screened for known streptococcal pyrogenic exotoxin (Spe) genes, smeZ, and ssa. The average incidence rate was 3.1 cases per 100,000 individuals. The most prevalent sequence types (STs) were STs 52, 28, and 334. In association with emm types 28, 77, and 87, the serotype T-28 comprised 24.8% of the strains. emm types 28, 1, and 82 were dominating. In 2007, a sharp increase in the number of emm-6 strains was noted. All strains were sensitive to penicillin and quinupristin-dalfopristin, while 3.4% and 6.1% of the strains were resistant to macrolides and tetracycline, respectively. Furthermore, the emm-6 strains had intermediate susceptibility to ofloxacin. Isolates displayed a wide variety of gene profiles, as shown by the presence or absence of the Spe genes, smeZ, and ssa, but 48% of the isolates fell into one of three profiles. In most cases, an emm type was restricted to one gene profile. Although the incidence decreased during this study, invasive GAS disease still has a high endemic rate, with involvement of both established and emerging emm types displaying variability in virulence gene profiles as well as differences in gender and age group preferences.

Indirect effect of conjugate pneumococcal vaccination in a 2+1 dose schedule

In 2006, the heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in the Norwegian Childhood Vaccination Programme in a 2+1 dose schedule; immunisations are administered at 3, 5 and 12 months. Changes in invasive pneumococcal disease in all ages from the baseline years 2004-2005 to 2008 were assessed, focusing on the indirect effect in the unvaccinated population. Following the introduction of PCV7, incidence rates of IPD caused by vaccine serotypes declined across all age groups, the decline being statistically significant for the age groups <5 years, 5-19 years, 40-64 years and > or = 65 years. In the unvaccinated population aged > or = 5 years the incidence rate of IPD caused by PCV7 serotypes declined by 48% from 12.34 cases/100,000 population to 6.44 cases/100,000 population, accounting for 74% of prevented cases of IPD in 2008. Among the adults aged > or = 65 years the incidence rate of IPD caused by serotypes not included in PCV7 increased. No vaccine failure was identified, indicating a very high effectiveness of the 2+1 dose schedule vaccination programme.

Seroepidemiological study after a long-distance industrial outbreak of legionnaires' disease

Following a long-distance outbreak of Legionnaires' disease from an industrial air scrubber in Norway in 2005, a seroepidemiological study measuring levels of immunoglobulin G (IgG) and IgM antibodies to Legionella pneumophila was performed with a polyvalent enzyme-linked immunosorbent assay. One year after the outbreak, IgG levels in employees (n = 213) at the industrial plant harboring the scrubber and in blood donors (n = 398) from the outbreak county were low but significantly higher (P < or = 0.002) than those in blood donors (n = 406) from a nonexposed county. No differences in IgM levels among the three groups were found after adjustment for gender and age. Home addresses of the seroresponders in the exposed county clustered to the city of the outbreak, in contrast to the scattering of addresses of the seroresponding donors in the nonexposed county. Factory employees who operated at an open biological treatment plant had significantly higher IgG and IgM levels (P < or = 0.034) than those working >200 m away. Most of the healthy seroresponders among the factory employees worked near this exposure source. Immunoblotting showed that IgG and IgM antibodies in 82.1% of all seroresponders were directed to the lipopolysaccharide of the L. pneumophila serogroup 1 outbreak strain. In conclusion, 1 year after the long-distance industrial outbreak a small increase in IgG levels of the exposed population was observed. The open biological treatment plant within the industrial premises, however, constituted a short-distance exposure source of L. pneumophila for factory employees working nearby.

Immunogenicity of fractional doses of tetravalent a/c/y/w135 meningococcal polysaccharide vaccine: results from a randomized non-inferiority controlled trial in Uganda

BACKGROUND

Neisseria meningitidis serogroup A is the main causative pathogen of meningitis epidemics in sub-Saharan Africa. In recent years, serogroup W135 has also been the cause of epidemics. Mass vaccination campaigns with polysaccharide vaccines are key elements in controlling these epidemics. Facing global vaccine shortage, we explored the use of fractional doses of a licensed A/C/Y/W135 polysaccharide meningococcal vaccine.

METHODS AND FINDINGS

We conducted a randomized, non-inferiority trial in 750 healthy volunteers 2-19 years old in Mbarara, Uganda, to compare the immune response of the full dose of the vaccine versus fractional doses (1/5 or 1/10). Safety and tolerability data were collected for all subjects during the 4 weeks following the injection. Pre- and post-vaccination sera were analyzed by measuring serum bactericidal activity (SBA) with baby rabbit complement. A responder was defined as a subject with a > or =4-fold increase in SBA against a target strain from each serogroup and SBA titer > or =128. For serogroup W135, 94% and 97% of the vaccinees in the 1/5- and 1/10-dose arms, respectively, were responders, versus 94% in the full-dose arm; for serogroup A, 92% and 88% were responders, respectively, versus 95%. Non-inferiority was demonstrated between the full dose and both fractional doses in SBA seroresponse against serogroups W135 and Y, in total population analysis. Non-inferiority was shown between the full and 1/5 doses for serogroup A in the population non-immune prior to vaccination. Non-inferiority was not shown for any of the fractionate doses for serogroup C. Safety and tolerability data were favourable, as observed in other studies.

CONCLUSIONS

While the advent of conjugate A vaccine is anticipated to largely contribute to control serogroup A outbreaks in Africa, the scale-up of its production will not cover the entire "Meningitis Belt" target population for at least the next 3 to 5 years. In view of the current shortage of meningococcal vaccines for Africa, the use of 1/5 fractional doses should be considered as an alternative in mass vaccination campaigns.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00271479.

Tracking airborne Legionella and Legionella pneumophila at a biological treatment plant

Biological treatment plants are frequently used to degrade organic substances in wastewater from wood refinement processes. Aeration ponds in such plants provide an optimal growth environment for many microorganisms, including Legionella species. To investigate whether legionellae could be dispersed as aerosols from the ponds and transported by the wind, the wetted-wall cyclone SASS 2000(PLUS) and the impactors MAS-100 and STA-204 were used to collect air samples directly above, upwind, and downwind of aeration ponds during a 4-month period. Computational fluid dynamics was used a priori to estimate the aerosol paths and to determine suitable air-sampling locations. Several Legionella species, including Legionella pneumophila, were identified in air samples at the biological treatment plant using microbiological and molecular methods. L. pneumophila was identified up to distances of 200 m downwind from the ponds, but, in general, not upwind nor outside the predicted aerosol paths. The highest concentration level of viable legionellae was identified directly above the aeration ponds (3300 CFU/m3). This level decreased as the distance from the aeration ponds increased. Molecular typing indicated that a single clone of L. pneumophila was dispersed from the ponds during the period of the study. Thus, our study demonstrated that aerosols generated at aeration ponds of biological treatment facilities may contain L. pneumophila, which then can be transported by the wind to the surroundings. The methods used in this study may be generically applied to trace biological aerosols that may pose a challenge to environmental occupational health.

Sequence type and emm type diversity in Streptococcus pyogenes isolates causing invasive disease in Norway between 1988 and 2003

The incidence of invasive group A streptococcal disease has increased in Norway since the 1980s. Analysis of 100 isolates recovered from 1988 to 2003 showed an increased genotypic diversity over time, while the prevalence of the strain that dominated in 1988, sequence type (ST)-28/emm-1, decreased. Necrotizing fasciitis was often associated with ST-15/emm-3.

Effectiveness of a 2+1 dose schedule pneumococcal conjugate vaccination programme on invasive pneumococcal disease among children in Norway

The 7-valent pneumococcal conjugate vaccine (PCV-7) was licensed in Norway in 2001. In July 2006, PCV-7 was introduced in the Norwegian Childhood Vaccination Programme in a 2+1 dose schedule, with immunizations administered at 3, 5 and 12 months of age. PCV-7 was offered through the vaccination programme to all children born from January 2006, i.e. a catch-up for children aged 3-6 months. Prior to 2006 the use of PCV-7 was negligible. The effectiveness of the PCV-7 vaccination programme was assessed using data on invasive pneumococcal disease (IPD) incidence obtained from the Norwegian Surveillance System for Communicable Diseases, serotype distribution from the National Reference Laboratory for Pneumococci, and vaccine coverage and vaccination status from the Norwegian National Vaccination Register. Vaccine coverage quickly reached high levels; 95% of children >3 months born from January 2006 had received at least one immunization with PCV-7. The incidence rate of IPD among children <2 years rapidly declined; the rate of vaccine serotype IPD in this age group fell from an average of 47.1 cases/100,000 population in the 2 years prior to PCV-7 introduction to 13.7 cases/100,000 population in 2007. The incidence rate of nonvaccine serotype IPD remained stable. The vaccine programme effectiveness was estimated to be 74% (95% CI 57-85%). No vaccine failure was seen after complete primary immunization with two vaccine doses. Our findings indicate that PCV-7 provides highly effective protection against vaccine serotype IPD when administered in a 2+1 dose schedule.

Detection of measles- and mumps-specific IgG antibodies in paired serum and oral fluid samples from Norwegian conscripts

The aim of this study was to measure the seroprevalence to mumps in Norwegian conscripts belonging to the first children vaccination cohorts that had been offered two doses of MMR vaccine. The seroprevalence to mumps was 76% with the Microimmune assay and 85% with the Enzygnost assay. We also compared the performance of the Microimmune assay for detection of mumps- and measles-specific IgG antibodies in 340 paired serum and oral fluid samples from the conscripts and evaluated the effect of revaccination. Mumps-specific IgG antibodies were detected in only 61% of the oral fluids. In contrast, high levels of measles-specific IgG antibodies were detected in both the serum and oral fluid samples. Based on these results, we are only able to recommend the use of oral fluid for surveillance of measles in Norway. Our results may also indicate that the seroprevalence necessary to interrupt transmission of mumps has not been reached in vaccinated young adult Norwegians. Seroconversion was observed in all initially measles seronegative conscripts after revaccination, whereas 23 of 27 initially mumps seronegative conscripts failed to seroconvert.

Immunogenicity and safety of a combination of two serogroup B meningococcal outer membrane vesicle vaccines

MenBvac and MeNZB are safe and efficacious vaccines against serogroup B meningococcal disease. MenBvac is prepared from a B:15:P1.7,16 meningococcal strain (strain 44/76), and MeNZB is prepared from a B:4:P1.7-2,4 strain (strain NZ98/254). At 6-week intervals, healthy adults received three doses of MenBvac (25 microg), MeNZB (25 microg), or the MenBvac and MeNZB (doses of 12.5 microg of each vaccine) vaccines combined, followed by a booster 1 year later. Two-thirds of the subjects who received a monovalent vaccine in the primary schedule received the other monovalent vaccine as a booster dose. The immune responses to the combined vaccine were of the same magnitude as the homologous responses to each individual vaccine observed. At 6 weeks after the third dose, 77% and 87% of the subjects in the combined vaccine group achieved serum bactericidal titers of > or = 4 against strains 44/76 and NZ98/254, respectively, and 97% and 93% of the subjects achieved a fourfold or greater increase in opsonophagocytic activity against strains 44/76 and NZ98/254, respectively. For both strains, a trend of higher responses after the booster dose was observed in all groups receiving at least one dose of the respective strain-specific vaccine. Local and systemic reactions were common in all vaccine groups. Most reactions were mild or moderate in intensity, and there were no vaccine-related serious adverse events. The safety profile of the combined vaccine was not different from those of the separate monovalent vaccines. In conclusion, use of either of the single vaccines or the combination of MenBvac and MeNZB may have a considerable impact on the serogroup B meningococcal disease situation in many countries.

Opsonophagocytic activity and other serological indications of Bordetella pertussis infection in military recruits in Norway

Bordetella pertussis is the causative agent of pertussis (whooping cough). Despite high vaccination coverage, pertussis remains a significant disease in many countries. Besides vaccination, transient carriage of Bordetella spp. or other cross-reacting organisms adds to the immunity against pertussis. However, the various immunological mechanisms conferring protection remain largely unknown. In this study, paired serum samples from 464 healthy Norwegian military recruits were collected, the first at enrolment and the second about 8 months later. The prevalence of pertussis during military service was examined by comparing the paired serum samples for immunoglobulin G (IgG) antibodies against pertussis toxin (PT) by enzyme-linked immunosorbent assay (ELISA). Seventy-eight percent of the recruits had low levels of IgG antibodies against PT in both samples. Conversely, 8.4% of the recruits demonstrated high anti-PT IgG levels in the first sample, indicative of recent pertussis prior to enrolment. One recruit experienced seroconversion, indicating pertussis during service. A subset of 248 serum samples with low, medium, and high anti-PT IgG titers were analyzed by a different ELISA kit for IgG and IgA antibodies against PT and filamentous hemagglutinin (FHA) and for opsonophagocytic activity (OPA), for induction of C3b deposition products, and for IgG binding with live B. pertussis as the antigen. We observed high correlations between OPA and IgG against live bacteria (r = 0.83), between OPA and IgG anti-FHA (r = 0.79), between OPA and anti-PT IgG (r = 0.68), and between OPA and C3b binding (r = 0.70) (P < 0.0001 for all). Anti-PT IgA did not correlate closely with the other assays.

Rapid Spread in Norway of an Erythromycin-Resistant Pneumococcal Clone, Despite Low Usage of Macrolides

During the last 4 years, Norway has experienced an increase in macrolide resistance among systemic isolates of Streptococcus pneumoniae. The Norwegian reference laboratory for pneumococci received the isolates from over 85% of the Norwegian cases of systemic pneumococcal disease in the period studied. To study the details of the increased macrolide resistance, all macrolide-resistant systemic pneumococcal isolates (410 isolates) collected in the period from 1995 to 2005 were characterized phenotypically, and a representative selection of 68 strains was also studied genotypically. The serogroups most frequently associated with macrolide resistance in the studied period were 14, 6, 23, 19, and 9. The resistance M-type was expressed in 85% of the resistant isolates. Of the 68 isolates analyzed by multilocus sequence typing, 19 different sequence types (STs) were represented, including several of the international resistant clones. All but one of the clones appeared at a low frequency; mainly as isolated cases. The increase in macrolide resistance seen from 2001 to 2005 proved to be caused by ST-9, defined as the England(14)-9 clone by the Pneumococcal Molecular Epidemiology Network. All ST-9 isolates tested, carried the mef(A) gene and expressed the resistance M-type. This clone first appeared in the Oslo region in 1993, but was by 2005 isolated from all over the country. Children were overrepresented among the cases caused by this clone; however, people aged 20-29, possibly involving the parent generation, were also represented at an increased frequency. The England(14)-9 clone has been able to spread successfully in the Norwegian population despite a relatively low consumption of macrolides.

Pharyngeal carriage of Neisseria meningitidis in 2–19-year-old individuals in Uganda

In southern Uganda, only sporadic cases of serogroup A meningococcal disease have been reported since 2000. As part of an immunogenicity study of the tetravalent meningococcal polysaccharide vaccine, nasopharyngeal swab samples were collected twice, 4 weeks apart, from 2-19-year-old healthy individuals in Mbarara, Uganda. Only 15 (2.0%) of the 750 individuals carried meningococci asymptomatically. Most of the strains were non-serogroupable and none were serogroup A. However, two individuals carried a serogroup W135 strain, sequence type (ST)-11, similar to the clone that was responsible for the epidemic in Burkina Faso in 2002. Our study further demonstrates the geographical spread of serogroup W135 ST-11 strain and thus the potential epidemic risk.

Persisting immune responses indicating long-term protection after booster dose with meningococcal group B outer membrane vesicle vaccine

MenBvac is an outer membrane vesicle vaccine against systemic meningococcal disease caused by serogroup B Neisseria meningitidis. In this placebo-controlled double-blind study including 374 healthy adolescents, the safety and immunogenicity of a schedule of three primary doses 6 weeks apart followed by a fourth dose a year later were evaluated. Antibody responses to the vaccine strain and heterologous strains (non-vaccine-type strains) and the persistence of these antibodies were measured by the serum bactericidal assay (SBA) and enzyme-linked immunosorbent assay up to 1 year after the last dose. The proportion of subjects with SBA titers of > or = 4 against the vaccine strain increased from 3% prevaccination to 65% after the third dose. Ten months later, this proportion had declined to 28%. The fourth dose induced a booster response demonstrated by 93% of subjects achieving a titer of > or = 4. One year after the booster dose, 64% still showed SBA titers of > or = 4. Cross-reacting antibodies were induced against all heterologous strains tested, although the magnitude of SBA titers differed widely between the different strains. All four doses of MenBvac were safe. Both MenBvac and the placebo had reactogenicity profiles of mild to moderate local and systemic reactions. Pain, the most common reaction, was reported with similar frequencies in both groups. No serious adverse events occurred in the MenBvac group. This study confirmed the good immunogenicity of the primary course of MenBvac and demonstrated prolonged persistence and increased cross-reactivity of functional antibodies elicited by a booster dose.

Carriage of Streptococcus pneumoniae in healthy Norwegian children attending day-care centres

An observational study to examine Streptococcus pneumoniae carriage in Norwegian children was initiated after two cases of pneumococcal meningitis, caused by the England(14)-9 clone, occurred in one day-care centre in Oslo. All children recruited from the day-care centre where the cases occurred were vaccinated with a seven-valent pneumococcal conjugate vaccine; the other participants who attended three other day-care centres nearby were not. The children were followed for 9 months, and three samplings took place. At the first visit, 45.7% of the children were colonised by pneumococci in the nasopharynx. The children harboured a variety of serotypes, with serotypes 6A, 23F, 6B and 19F being the most frequent. The numbers of children carrying vaccine serotypes decreased in both the vaccinated and the non-vaccinated groups. Thus, no significant effect of vaccine on carriage was detected in this relatively small study.

Interlaboratory standardization of the measurement of serum bactericidal activity by using human complement against meningococcal serogroup b, strain 44/76-SL, before and after vaccination with the Norwegian MenBvac outer membrane vesicle vaccine

There is currently no standardized serum bactericidal antibody (SBA) assay for evaluating immune responses to meningococcal outer membrane vesicle or protein vaccines. Four laboratories, Manchester Health Protection Agency (MC HPA), New Zealand Institute of Environmental Science and Research Limited (NZ ESR), Norwegian Institute of Public Health (NIPH), and Chiron Vaccines (Chiron), measured SBA titers in the same panel of human sera (n=76) from laboratory staff (n=21) vaccinated with MenBvac. Blood samples were collected prevaccination, prior to each of the three doses of MenBvac given at 6-week intervals, and 6 weeks following the third dose. Initial results showed a number of discrepancies in results between the four participating laboratories. The greatest effect on titers appeared to be due to differences among laboratories in the maintenance of the meningococcal serogroup B test strain, 44/76-SL. A repeat study was conducted using the same frozen isolate (meningococcal serogroup B test strain 44/76-SL), freshly distributed to all four laboratories. Using SBA titers from the tilt method for all samples, and using MC HPA as the comparator, the results were as follows for NZ ESR, NIPH, and Chiron, respectively, using log(10) titers: correlation coefficients (r) were 0.966, 0.967, and 0.936; intercepts were 0.08, 0.15, and 0.17; and slopes were 0.930, 0.851, and 0.891. In both prevaccination and postvaccination samples from 15 subjects assayed by all four laboratories, similar increases in SBA (fourfold or greater) were observed (for 11, 11, 9, and 9 subjects for MC HPA, NZ ESR, NIPH, and Chiron, respectively), and similar percentages of subjects with SBA titers of>or=4 p revaccination and 6 weeks following each dose were found. The SBA assay has been harmonized between the four different laboratories with good agreement on seroconversion rates, n-fold changes in titers, and percentages of subjects with SBA titers of >or=4.

Combined administration of meningococcal serogroup B outer membrane vesicle vaccine and conjugated serogroup C vaccine indicated for prevention of meningococcal disease is safe and immunogenic

MenBvac and Menjugate are safe and efficacious vaccines. The purpose of this study was to evaluate safety and immunogenicity of the combination (MenB/C) of the lyophilized active components of the conjugated group C vaccine Menjugate when reconstituted with the full liquid group B outer membrane vesicle vaccine MenBvac compared to MenBvac and Menjugate given separately. At 6-week intervals, healthy adults were given one dose of MenB/C followed by two doses of MenBvac (MenB/C group), three doses of MenBvac (MenB group), or one dose of Menjugate and two doses of placebo (MenC group). Injection site reactions were frequent in all groups. However, most reactions were short lasting and mild or moderate in intensity, and the vaccines were found to be well tolerated, with no vaccine-related serious adverse events. MenB/C was immunogenic with regard to both serogroup B and C meningococci. Both the serum bactericidal assay and the enzyme-linked immunosorbent assay analyses showed that the immune responses of the combination vaccine were similar to the immune responses of its separate components MenBvac and Menjugate for both serogroup B and C. In conclusion, the combined MenB/C vaccine is safe and immunogenic. The two vaccines do not interact negatively with each other and can easily be administered in the same syringe. The induced immune responses suggest that the combined vaccine is likely to confer protection against systemic group B disease caused by the vaccine strain as well as against group C meningococcal disease.

Pneumococcal conjugate vaccine followed by pneumococcal polysaccharide vaccine; immunogenicity in patients with ataxia-telangiectasia

The immunodeficiency in Ataxia-telangiectasia (A-T) is characterised by low T and B cell counts, low levels of IgE, IgA and/or IgG2, and especially low levels of pneumococcal antibodies. The 23-valent pneumococcal polysaccharide vaccine (PPV23) has previously been shown not to be effective in A-T, but these patients are capable of making protective antibodies to other vaccines such as diphtheria and tetanus toxin, promising effect of the seven-valent pneumococcal conjugated vaccine (PCV7). Nine A-T patients and 25 age and sex matched controls were vaccinated with both PCV7 and PPV23, and three A-T patients were vaccinated with PCV7 only. In the A-T patients, no significant increase in pneumococcal antibody levels were observed after the single PCV7, while the subsequent PPV23 vaccination resulted in a significant increase in antibody levels to the PPV23 mix, as well as to serotype 4, 14, 19F and to the geometric mean of serotype 4, 6B, 14, 18C, 19F, 23F which increased from median 0.2 (range 0.1-0.5) microg/mL to 0.6 (0.2-1.5) microg/mL (P= 0.014). Compared to the patients' baseline levels, the vaccinations induced a 1.5- to 7-fold increase in antibodies to the six different serotypes tested. The increases in pneumococcal antibody titres were lower than those observed in the controls (9- to 34-fold increase). The results are valuable in planning the care of A-T patients, using PCV7 to trigger and PPV23 to booster the immune response and possibly prevent severe pneumococcal disease.

The concept of ?tailor-made?, protein-based, outer membrane vesicle vaccines against meningococcal disease

Protein-based, outer membrane vesicle (OMV) vaccines have previously proven to be efficacious against serogroup B meningococcal disease in Norway and Cuba. Currently, a public health intervention is going on in order to control a serogroup B epidemic in New Zealand. The scale-up and standardization of vaccine production required for controlling the New Zealand epidemic has allowed the establishment of large-scale GMP manufacturing for OMV vaccines. The outcome of this will be licensing of the vaccine in New Zealand and possibly other countries. The availability of licensed OMV vaccines raises the question of whether such vaccines may provide the opportunity to control other outbreaks and epidemics. For instance, such a vaccine could control a localised outbreak of group B meningococci in Normandy, France. "Tailor-made" vaccines, focusing on the sub-capsular antigens may also be considered for use in sub-Saharan Africa for the prevention of the recurrent outbreaks by serogroups A and W135 meningococci. This assumption is based on the epidemiological observation that meningococcal outbreaks in Africa are clonal and are strikingly stable regarding their phenotypic characteristics.

International validation of novel pyrogen tests based on human monocytoid cells

It is a requirement that parenteral medicines be tested for pyrogens (fever causing agents) using one of two animal-based tests: the rabbit pyrogen test and the bacterial endotoxin test. Understanding the human fever reaction has led to novel non-animal alternative tests based on in vitro activation of human monocytoid cells in response to pyrogens. Using 13 prototypic drugs, clean or contaminated with pyrogens, we have validated blindly six novel pyrogen tests in ten laboratories. Compared with the rabbit test, the new tests have a lower limit of detection and are more accurate as well as cost and time efficient. In contrast to the bacterial endotoxin test, all tests are able to detect Gram-positive pyrogens. The validation process showed that at least four of the tests meet quality criteria for pyrogen detection. These validated in vitro pyrogen tests overcome several shortcomings of animal-based pyrogen tests. Our data suggest that animal testing could be completely replaced by these evidence-based pyrogen tests and highlight their potential to further improve drug safety.

The impact of an early truncating founder ATM mutation on immunoglobulins, specific antibodies and lymphocyte populations in ataxia-telangiectasia patients and their parents

Eleven Norwegian patients (aged 2-33 years, seven males and four females) with Ataxia-telangiectasia (A-T) and their parents were investigated. Five of the patients were homozygous for the same ATM mutation, 3245delATCinsTGAT, a Norwegian founder mutation. They had the lowest IgG2 levels; mean (95% confidence interval) 0.23 (0.05-0.41) g/l versus 0.91 (0.58-1.26) g/l in the other patients (P = 0.002). Among the 11 A-T patients, six had IgG2 deficiency, six had IgA deficiency (three in combination with IgG2 deficiency) and seven had low/undetectable IgE values. All patients had very low levels of antibodies to Streptococcus pneumoniae 0.9 (0.4-1.4) U/ml, while normal levels were found in their parents 11.1 (8.7-13.4) U/ml (P < 0.001). A positive linear relationship between pneumococcal antibodies and IgG2 (r = 0.85, P = 0.001) was found in the patients. Six of 11 had diphtheria antibodies and 7 of 11 tetanus antibodies after childhood vaccinations, while 4 of 7 Hemophilus influenzae type b (Hib) vaccinated patients had protective antibodies. Ten patients had low B cell (CD19+) counts, while six had low T cell (CD3+) counts. Of the T cell subpopulations, 11 had low CD4+ cell counts, six had reduced CD8+ cell counts, and four had an increased portion of double negative (CD3+/CD4-/CD8-) gamma delta T cells. Of the 22 parents (aged 23-64 years) 12 were heterozygous for the ATM founder mutation. Abnormalities in immunoglobulin levels and/or lymphocyte subpopulations were also observed in these carriers, with no correlation to a special ATM genotype.

Immunisation schedules for non-replicating nasal vaccines can be made simple by allowing time for development of immunological memory

Mice immunised intranasally with multiple doses of outer membrane vesicles (OMVs) from group B meningococci developed antibody responses that depended on the interval between doses. High levels of antibodies in saliva and extracts of faeces were induced within 4 weeks after an OMV vaccine had been given at weekly intervals, whereas the antibody responses in these samples were negligible when given four times at 1-day or 1-h intervals, or as one large dose. Only modest responses were obtained in serum after 4 weeks, however, whether the vaccine had been given repeatedly at any schedule, including the 1-week interval, or as one dose. On the other hand, two large doses given 8 weeks apart induced booster antibody responses in both serum and secretions that matched the responses from a second series of the four smaller doses. Intranasal immunisations may thus stimulate immunological memory more rapidly in secretions than in serum. In order to secure adequate systemic responses by a minimum of doses, nasal vaccines should therefore be given at intervals longer than 4 weeks, in harmony with the intervals recommended for injectable vaccines.

The immune response to pneumococcal polysaccharide vaccine in zinc-depleted mice

Zinc depletion affects several facets of the immune system and the resistance to infections. We assessed the effect of zinc deprivation on the immune response to the pneumococcal polysaccharide antigens in the commercially available Pneumovax pneumococcal vaccine. Young female BALB/c mice were fed diets with 2.7, 5.8 or 25 micro g of elemental zinc per mg diet. After six weeks of pair feeding, there were significant differences in the mean body weights between the feeding groups and we demonstrated a dose response of the zinc level in the diet on growth. The induced zinc deficiency had no discernible effect on the antipneumococcal polysaccharide immunoglobulin M (IgM) response following immunization with the pneumococcal vaccine. Although zinc depletion has a detrimental effect on the immune system, the murine T-cell-independent response to antigens such as those in the pneumococcal polysaccharide capsule does not seem to be affected.

Serum bactericidal activity correlates with the vaccine efficacy of outer membrane vesicle vaccines against Neisseria meningitidis serogroup B disease

For evaluation of serum bactericidal activity (SBA) as surrogate for the efficacy of outer membrane vesicle (OMV) vaccines against Neisseria meningitidis serogroup B disease, we have reanalyzed data from a randomized double blind placebo-controlled efficacy trial involving 172000 secondary school students (aged 13-14 years) in Norway (1988-1991). A cohort of the efficacy trial consisting of 880 individuals was selected for immunogenicity studies. An efficacy of 87% was calculated for a 10-month observation period. However, after an observation period of 29 months, the estimated efficacy against group B disease induced by vaccination was 57%. The immunogenicity study showed that the SBA geometric mean titer (GMT) for the vaccinees was 2.4 before vaccination and 19.0 six weeks after the second vaccine dose. One year after vaccination the GMT was reduced to 2.8. A separate three-dose study with 304 adolescents showed that with a third dose at 10 months after the second dose (i.e. when cases of disease started to appear) a strong booster response was induced. Ten months after the second dose the SBA was reduced to near pre-immunization level. Following the third dose the SBA geometric mean titer of 2.7 increased to 62.3. One year after the third dose, the GMT was markedly higher than 6 weeks after the second dose (12.6 versus 8.8). Thus, protection after vaccination corresponds with the level of SBA. In order to reach lasting protective levels of SBA in a population, three vaccine doses are probably required. Measurements of SBA are likely to be useful for evaluating various upcoming formulations and improvements of immunization regimens for OMV vaccines.

Cancer patients undergoing chemotherapy show adequate serological response to vaccinations against influenza virus and Streptococcus pneumoniae

Cancer patients receiving chemotherapy are prone to develop infections that might postpone treatment and lead to complications. The aim of our study was to investigate whether a heterogeneous population of patients with solid tumors and malignant lymphoma undergoing chemotherapy would respond serologically to vaccination against influenza and pneumococcal disease. There are no established routines in oncology departments in Norway regarding vaccination of these patients. The study included 35 cancer patients with median age 53 yr (range 20-74) and 38 controls with median age 57 yr (range 43-75). The chemotherapy regimens used were mild or moderately immunosuppressive. After one vaccination, 25 patients (72%) and 34 controls (87%) were serologically protected against two or three influenza strains. A higher proportion of patients with solid tumors (81%) than lymphoma (38%) achieved protection. Age, months on chemotherapy, and curative versus palliative treatment did not influence responses to vaccination. After vaccination with a 23-valent polysaccharide vaccine against pneumococci, most patients and controls achieved protective serum levels of antibodies against the different serotypes, with the exception that fewer patients were protected against serotype 4. The responses in controls were, however, generally stronger to all serotypes. Tumor type did not influence this vaccination response. We conclude that our cancer patients achieved adequate responses to influenza virus and Streptococcus pneumoniae. These are not live vaccines and are therefore safe for immunocompromised patients. Routine vaccinations against influenza virus and Streptococcus pneumoniae should be considered in cancer patients undergoing mild to moderately immunosuppressive chemotherapy.

Influence of intravenous anesthesia on mucosal and systemic antibody responses to nasal vaccines

Inhalation of antigens may stimulate the immune system by way of the upper as well as the lower airways. We have shown that at least 1,000 times more live pneumococci were recovered from pulmonary tissue after being presented as drops of a liquid suspension onto the nares of anesthetized mice compared to the number of bacteria recovered from animals that were not anesthetized in the course of the challenge. Mice that were similarly immunized intranasally by inhalation of three different nonreplicating particulate vaccine formulations, i.e., a meningococcal outer membrane vesicle (OMV) vaccine, a formalin-inactivated whole-virus influenza (INV) vaccine, and the INV vaccine with OMVs as a mucosal adjuvant, during general intravenous anesthesia developed concentrations of vaccine-specific serum immunoglobulin G (IgG) antibodies that were four to nine times higher than in mice that were fully awake during immunizations. The concentrations of IgA antibodies in serum were also higher in anesthetized than in nonanesthetized mice and correlated positively with the corresponding levels of serum IgG antibodies in the anesthetized but not in the nonanesthetized mice. In saliva and feces, however, the concentrations of IgA antibodies were equally high whether or not the animals were dormant during immunizations. The results indicate that intrapulmonary antigen presentation, as a part of an intranasal immunization strategy, is of importance for systemic but not for mucosal antibody responses. A major portion of IgA antibodies in serum may thus be derived from nonmucosal sites.

Predictive value of immunologic parameters and HIV RNA in relation to humoral pneumococcal polysaccharide vaccine responses in patients with HIV infection

In the study presented here immunologic markers and HIV RNA were related to specific antibody responses in 50 HIV-infected patients who had moderate immunodeficiency (median CD4+, 295) and were vaccinated with a pneumococcal polysaccharide vaccine. Low responses were associated with low IgG2 or high IgM levels ( P=0.01) and good responses with high IgG4 ( P=0.05) or IgG2 ( P=0.07) or low beta(2) microglobulin ( P=0.04) levels. A combination of IgG2 levels >1.0 g/l and IgM <1.6 g/l at baseline significantly predicted a twofold or better response in logistic regression analysis ( P=0.025). Neither CD4+ lymphocyte counts nor HIV RNA levels were predictive, but it should be noted that good antibody responses were not restricted to patients with high CD4+ cell counts or low HIV RNA levels.

Humoral immunity to viral and bacterial antigens in lymphoma patients 4-10 years after high-dose therapy with ABMT. Serological responses to revaccinations according to EBMT guidelines

The aim of this study was to investigate the late effects of ABMT on the immune system with regard to protective humoral immunity against common antigens and responses to recall antigens (vaccines). The vaccines were given according to EBMT guidelines from 1995. The protocol included 35 patients with malignant lymphoma in CR 4-10 years after ABMT, and 35 controls. The results show that prior to ABMT the proportion of patients with protective immunity against poliomyelitis, tetanus and diphtheria was similar to that of controls. At study entry 4-10 years after ABMT, the proportion of patients with protective immunity against poliomyelitis and diphtheria was reduced, while all patients maintained protection against tetanus. A significant decrease in geometric mean antibody concentrations or titres was observed against all three antigens during this period. Serum levels of antibodies against different pneumococcal serotypes were lower in the patients than in the controls prior to vaccination. The responses to pneumococcal vaccination, which is considered to be a T cell-independent vaccine, were studied. Unlike controls, a minority of patients achieved protective levels of antibodies after a single vaccination. Despite persistent levels of protective antibodies in many patients post ABMT, secondary booster responses after one vaccination with T cell-dependent vaccines (tetanus, diphtheria and polio) were absent. In conclusion, this study shows that post ABMT, a full re-vaccination program was necessary to mount responses comparable to those observed after a single vaccination in controls.

Meningococcal outer membrane vesicle vaccine given intranasally can induce immunological memory and booster responses without evidence of tolerance

We have studied the ability of outer membrane vesicle (OMV) vaccines from Neisseria meningitidis serogroup B to induce vaccine-specific antibody and spleen cell proliferative responses in mice after being administered intranasally (i.n.) and/or subcutaneously (s.c.). A series of four weekly i.n. doses (25 microg) without adjuvant or a single s.c. dose (2.5 microg) with aluminum hydroxide was followed 2 months later by secondary i.n. or s.c. immunizations. After i.n. priming, both immunoglobulin G (IgG) antibody responses in serum, measured by enzyme-linked immunosorbent assay, and IgA antibodies in saliva and extracts of feces were significantly boosted by later i.n. immunizations. The IgG antibody responses in serum were also significantly augmented by secondary s.c. immunization after i.n. as well as s.c. priming. Sera from mice immunized i.n. reached the same level of bactericidal activity as after s.c. immunizations. The s.c. immunizations alone, however, had no effect on mucosal IgA antibody responses, but could prime for booster antibody responses in secretions to later i.n. immunizations. The i.n. immunizations also led to marked OMV-specific spleen cell proliferation in vitro. Both serum antibody responses and spleen cell proliferation were higher after i.n. priming and later s.c. immunizations than after s.c. immunizations alone. There was thus no evidence that i.n. priming had induced immunological tolerance within the B- or T-cell system. Our results indicate that a nonproliferating meningococcal OMV vaccine given i.n. can induce immunological memory and that it may be favorably combined with similar vaccines for injections.

Radioimmunotherapy with iodine-131 tositumomab in patients with low-grade non-Hodgkin's B-cell lymphoma does not induce loss of acquired humoral immunity against common antigens

Thirty-one previously untreated patients with follicular low-grade B-cell non-Hodgkin's lymphoma expressing the CD20 antigen were treated with iodine-131 tositumomab therapy between 1996 and 1998. The therapy led to a temporary depletion of peripheral blood B-lymphocytes. Recovery of B-cells occurred in most cases by 3 to 6 months and in all patients by 12 months posttherapy. A temporary decline in T-cell subpopulations, but no reduction in serum immunoglobulin levels, could be observed. ELISA techniques were used to detect specific antibodies against rubella, mumps, varicella zoster, measles, and tetanus. Almost all patients remained seropositive against the different antigens during the 1- to 2-year follow-up. No significant reduction in antibody concentrations to tetanus or measles could be detected. The data show that acquired humoral immunity against common antigens appears to be preserved despite a temporary loss of B-lymphocytes.

Protective effect of Plantago major L. Pectin polysaccharide against systemic Streptococcus pneumoniae infection in mice

The antibacterial effect of a soluble pectin polysaccharide, PMII, isolated from the leaves of Plantago major, was examined in inbred NIH/OlaHsd and Fox Chase SCID mice experimentally infected with Streptococcus pneumoniae serotype 6B. Serotype 6B is known to give a more protracted infection when injected intraperitoneally into susceptible mice than more virulent serotypes like type 4. PMII was administered i.p. either once 3 days before challenge or once to thrice from 3 to 48 h after challenge. The number of bacteria in blood and the mouse survival rate were recorded. Pre-challenge administration of PMII and also lipopolysaccharide (LPS), included as a control, gave a dose-dependent protective effect against S. pneumoniae type 6B infection. However, injection of PMII after establishment of the infection in NIH/OlaHsd mice had no effect. The data demonstrate that, firstly, the polysaccharide fraction PMII from P. major protects against pneumococcal infection in mice when administered systemically prechallenge, and secondly that the protective effect is owing to stimulation of the innate and not the adaptive immune system.

Pneumococcal vaccine in the elderly: the Norwegian experience

Pneumococcal infections have increased during the last 10 to 15 years in Norway. Their incidence is now about 20 per 100,000 population for all age groups, but is 2 to 3 times higher among the elderly. In 1996, the Advisory Board of Infectious Disease Control, National Institute of Public Health, Norway, recommended that pneumococcal polysaccharide vaccine should be administered to all individuals aged > or = 65 years. This recommendation has led to an increased use of pneumococcal vaccine, with a marked peak during the influenza vaccination season.

Protective effect of beta-glucan against systemic Streptococcus pneumoniae infection in mice

The antimicrobial effect of soluble beta-1,3-D-glucan from Sclerotinia sclerotiorum (SSG) was examined in mice experimentally infected intraperitoneally (i.p.) with Streptococcus pneumoniae serotypes 4 and 6B. SSG was administered i.p. either 3 days before challenge or 3-48 h after challenge. The number of bacteria in blood samples and the mouse survival rates were recorded. Pre-challenge SSG administration protected dose-dependently against both S. pneumoniae type 4 and 6B infections. SSG injected 24 h post-challenge had a curative effect against type 6B but not type 4 pneumococcal infection. The data demonstrate that SSG administered systemically protects against pneumococcal infection in mice.