Pre-existing influenza-specific nasal IgA or nasal viral infection does not affect live attenuated influenza vaccine immunogenicity in children.

The United Kingdom has a national immunization programme which includes annual influenza vaccination in school-aged children, using live attenuated influenza vaccine (LAIV). LAIV is given annually, and it is unclear whether repeat administration can affect immunogenicity. Because LAIV is delivered intranasally, pre-existing local antibody might be important. In this study, we analysed banked samples from a study performed during the 2017/18 influenza season to investigate the role of pre-existing influenza-specific nasal immunoglobulin (Ig)A in children aged 6-14 years. Nasopharyngeal swabs were collected prior to LAIV immunization to measure pre-existing IgA levels and test for concurrent upper respiratory tract viral infections (URTI). Oral fluid samples were taken at baseline and 21-28 days after LAIV to measure IgG as a surrogate of immunogenicity. Antibody levels at baseline were compared with a pre-existing data set of LAIV shedding from the same individuals, measured by reverse transcription-polymerase chain reaction. There was detectable nasal IgA specific to all four strains in the vaccine at baseline. However, baseline nasal IgA did not correlate with the fold change in IgG response to the vaccine. Baseline nasal IgA also did not have an impact upon whether vaccine virus RNA was detectable after immunization. There was no difference in fold change of antibody between individuals with and without an URTI at the time of immunization. Overall, we observed no effect of pre-existing influenza-specific nasal antibody levels on immunogenicity, supporting annual immunization with LAIV in children.

Differences in nasal immunoglobulin A responses to influenza vaccine strains after live attenuated influenza vaccine (LAIV) immunization in children.

Different vaccine strains included in the live attenuated influenza vaccine (LAIV) have variable efficacy. The reasons for this are not clear and may include differences in immunogenicity. We report a Phase IV open-label study on the immunogenicity of a single dose of quadrivalent LAIV (Fluenz™ Tetra) in children during the 2015/16 season, to investigate the antibody responses to different strains. Eligible children were enrolled to receive LAIV; nasal samples were collected before and approximately 4 weeks after immunization. There was a significant increase in nasal immunoglobulin (Ig)A to the H3N2, B/Victoria lineage (B/Brisbane) and B/Yamagata lineage (B/Phuket) components, but not to the H1N1 component. The fold change in nasal IgA response was inversely proportional to the baseline nasal IgA titre for H1N1, H3N2 and B/Brisbane. We investigated possible associations that may explain baseline nasal IgA, including age and prior vaccination status, but found different patterns for different antigens, suggesting that the response is multi-factorial. Overall, we observed differences in immune responses to different viral strains included in the vaccine; the reasons for this require further investigation.

A pilot randomized trial of adjuvanted influenza vaccine in adult allogeneic hematopoietic stem cell transplant recipients.

The annual influenza vaccine is recommended for hematopoietic stem cell transplant (HSCT) patients although studies have shown suboptimal immunogenicity. Influenza vaccine containing an oil-in-water emulsion adjuvant (MF59) may lead to greater immunogenicity in HSCT recipients. We randomized adult allogeneic HSCT patients to receive the 2015-2016 influenza vaccine with or without MF59 adjuvant. Preimmunization and 4-week post-immunization sera underwent strain-specific hemagglutination inhibition assay. We randomized 73 patients and 67 (35 adjuvanted; 32 non-adjuvanted) had paired samples available at follow-up. Median age was 54 years (range 22-74) and time from transplant was 380 days (range 85-8107). Concurrent graft-versus-host disease was seen in 42/73 (57.5%). Geometric mean titers increased significantly after vaccination in both groups. Seroconversion to at least one of three influenza antigens was present in 62.9% vs 53.1% in adjuvanted vs non-adjuvanted vaccine (P=0.42). Factors associated with lower seroconversion rates were use of calcineurin inhibitors (P<0.001) and shorter duration from transplantation (P=0.001). Seroconversion rates were greater in patients who got previous year influenza vaccination (82.6% vs 45.5%, P=0.03). Adjuvanted vaccine demonstrated similar immunogenicity to non-adjuvanted vaccine in the HSCT population and may be an option for some patients.

Heterologous Immune Responses to Influenza Vaccine in Kidney Transplant Recipients.

Influenza vaccine is known to have suboptimal immunogenicity in transplant recipients. Despite this, influenza vaccine may have the added benefit of inducing a cross-reactive immune response to viral strains not found in the vaccine. This is termed "heterologous immunity" and has not been assessed previously in transplant patients. Pre- and postvaccination sera from kidney transplant recipients (n = 60) immunized with the 2012-2013 adjuvanted or nonadjuvanted influenza vaccine underwent testing by hemagglutination inhibition assay for strains not present in vaccine: A/New Caledonia/20/99 (H1N1), A/Texas/50/2012 (H3N2) and B/Brisbane/60/2008. The geometric mean titer of antibody to heterologous strains increased after vaccine (H1N1: 80.0 to 136.1, p < 0.001; H3N2: 23.3 to 77.3, p < 0.001; B: 13.3 to 19.5, p < 0.001). Seroconversion rates were 16.7%, 41.7%, and 13.3%, respectively. No differences in heterologous response were seen in the adjuvanted versus nonadjuvanted groups. Patients were more likely to seroconvert for a cross-reactive antigen if they seroconverted for the specific vaccine antigen. Seroconversion to heterologous A/H3N2, for example, was 84.0% for homologous H3N2 seroconverters versus 11.4% for nonseroconverters (p < 0.001). This study provides novel evidence that transplant recipients are able to mount significant cross-protective responses to influenza vaccine that may be an additional, previously unknown benefit of immunization.

Population susceptibility to North American and Eurasian swine influenza viruses in England, at three time points between 2004 and 2011.

Age-stratified sera collected in 2004, 2008 and 2010 in England were evaluated for antibody to swine influenza A(H3N2) and A(H1N1) viruses from the United States or Europe as a measure of population susceptibility to the emergence of novel viruses. Children under 11 years of age had little or no measurable antibody to recent swine H3N2 viruses despite their high levels of antibody to recent H3N2 seasonal human strains. Adolescents and young adults (born 1968­1999) had higher antibody levels to swine H3N2 viruses. Antibody levels to swine H3N2 influenza show little correlation with exposure to recent seasonal H3N2 (A/Perth/16/2009) strains, but with antibody to older H3N2 strains represented by A/Wuhan/359/1995. Children had the highest seropositivity to influenza A(H1N1)pdm09 virus, and young adults had the lowest antibody levels to A/Perth/16/2009. No age group showed substantial antibody levels to A/Aragon/RR3218/2008, a European swine H1N1 virus belonging to the Eurasian lineage. After vaccination with contemporary trivalent vaccine we observed evidence of boosted reactivity to swine H3N2 viruses in children and adults, while only a limited boosting effect on antibody levels to A/Aragon/RR3218/2008 was observed in both groups. Overall, our results suggest that different vaccination strategies may be necessary according to age if swine viruses emerge as a significant pandemic threat.

Randomized controlled trial of high-dose intradermal versus standard-dose intramuscular influenza vaccine in organ transplant recipients.

The immunogenicity of standard intramuscular (IM) influenza vaccine is suboptimal in transplant recipients. Also, recent studies suggest that alloantibody may be upregulated due to vaccination. We evaluated a novel high-dose intradermal (ID) vaccine strategy. In conjunction, we assessed alloimmunity. Transplant recipients were randomized to receive IM or high-dose ID vaccine. Strain-specific serology and HLA alloantibody production was determined pre- and postimmunization. In 212 evaluable patients (105 IM, 107 ID), seroprotection to H1N1, H3N2 and B strains was 70.5%, 63.8% and 52.4% in the IM group, and 71.0%, 70.1%, 63.6% in the ID group (p=ns). Seroconversion to ≥1 antigen was 46.7% and 51.4% in the IM and ID groups respectively (p=0.49). Response was more likely in those≥6 months posttransplant (53.2% vs. 19.2%; p=0.001). Use of mycophenolate mofetil was inversely associated with vaccine response in a dose-dependent manner (p<0.001). Certain organ subgroups had higher response rates for influenza B in the ID vaccine group. Differences in anti-HLA antibody production were detected in only 3/212(1.4%) patients with no clinical consequences. High-dose intradermal vaccine is an alternative to standard vaccine and has potential enhanced immunogenicity in certain subgroups. In this large cohort, we also show that seasonal influenza does not result in significant alloantibody production.

Severe respiratory illness caused by a novel coronavirus, in a patient transferred to the United Kingdom from the Middle East, September 2012.

Coronaviruses have the potential to cause severe transmissible human disease, as demonstrated by the severe acute respiratory syndrome (SARS) outbreak of 2003. We describe here the clinical and virological features of a novel coronavirus infection causing severe respiratory illness in a patient transferred to London, United Kingdom, from the Gulf region of the Middle East.

Strategies for screening blood donors to source convalescent H1N1v plasma for intervention therapy.

BACKGROUND AND OBJECTIVES: During the 1918, pandemic blood components were successfully used to treat severe influenza pneumonia. A Proof of Principle trial investigating the clinical benefit of convalescent plasma was proposed in the 2009 H1N1v epidemic with the aim of screening donors for high titre antibody in order to stockpile plasma packs to be used for treatment for severe pneumonia. MATERIALS AND METHODS: Serum samples were collected from donors. IgG antibody capture format enzyme-linked immunoassays using recombinant proteins (GACELISAs) were compared with microneutralization (MN) and haemagglutination inhibition (HAI). The influence of age and history of influenza-like illness (ILI) on the detection of high titre antibody was examined. RESULTS: 1598 unselected donor sera collected in October and December 2009 were tested by HAI. The HAI and demographic data defined a possible strategy for selective donor screening. One of the GACELISAs was highly specific for recent infection but showed lower sensitivity than HAI. CONCLUSIONS: During the 2009 pandemic screening 17- to 30-year-old donors by HAI delivered around 10% with high antibody levels. The ELISA using a short recombinant H1N1v HA detected fewer reactives but was more specific for high titre antibody (≥1:256). Screening strategies are proposed based on using HAI on serum or GACELISA on plasma.

A 1-year follow-on study from a randomised, head-to-head, multicentre, open-label study of two pandemic influenza vaccines in children.

INTRODUCTION: Pandemic influenza A H1N1 infections occurred worldwide from 2009. Children were particularly vulnerable. Novel vaccines were used during the pandemic. OBJECTIVE: To assess the persistence of antibody to H1N1 influenza 1 year after children aged 6 months to 12 years had been immunised with two doses of either a non-adjuvanted whole-virion H1N1 influenza vaccine or an AS03B-adjuvanted split-virion H1N1 influenza vaccine; and also to assess the immunogenicity and reactogenicity in this population of a single dose of 2010-11 trivalent seasonal influenza vaccine. DESIGN: Multicentre, open-label, follow-on from randomised, head-to-head trial. SETTING: Five UK sites (Southampton, Oxford, Bristol, London and Exeter). PARTICIPANTS: Children who completed last year's head-to-head randomised study were invited to participate. Children who had subsequently received a further dose of H1N1 vaccine, or who had already received a dose of 2010-11 trivalent seasonal influenza vaccine, were excluded. INTERVENTIONS: In the previous study, children were randomised (in a 1 : 1 ratio) to receive two doses, 21 days apart, of either a non-adjuvanted whole-virion H1N1 influenza vaccine or an AS03B-adjuvanted split-virion H1N1 influenza vaccine. In this follow-on study, a blood sample was taken to assess the persistence of antibody 1 year later, followed by administration of one 0.5 ml-dose of trivalent seasonal influenza vaccine. A second blood sample was taken 3 weeks later. MAIN OUTCOME MEASURES: Comparison between vaccines of the percentage of participants with a microneutralisation (MN) titre ≥ 1 : 40 and a haemagglutination titre ≥ 1 : 32, 1 year after vaccination. Immunogenicity of the trivalent seasonal influenza vaccine was assessed 3 weeks after vaccination by both the MN and the haemagglutination inhibition (HI) titres. Reactogenicity data were recorded for 7 days after vaccination. RESULTS: A total of 323 children were enrolled and 318 were included in the analysis of the persistence of antibody. One year after receipt of whole-virion vaccine, the MN titre was ≥ 1 : 40 in 32.4% of those vaccinated when < 3 years old and in 65.9% of those vaccinated when ≥ 3 years old; the HI titre was ≥ 1 : 32 in 63.2% and 79.1% of children in the respective age groups. One year after receipt of the adjuvanted vaccine, the MN titre was ≥ 1 : 40 in 100% of those vaccinated when < 3 years old and in 96.9% of those vaccinated when ≥ 3 years old; the HI titre was ≥ 1 : 32 in 98.4% and 96.9% of children in the respective age groups. Three hundred and two children were given trivalent seasonal influenza vaccination. Three weeks later, sera were obtained from 282 children; 100% had an MN titre ≥ 1 : 40 and HI titre ≥ 1 : 32. Trivalent seasonal influenza vaccine was well tolerated, although in children < 5 years old, fever ≥ 38 °C was reported in 13.6% of those who had previously received whole-virion vaccine, and in 18.3% of those who had received adjuvanted vaccine. CONCLUSIONS: Nearly all children who received two doses of AS03B-adjuvanted split-virion pandemic H1N1 influenza vaccine had titres of antibody deemed protective (HI titre ≥ 1 : 32, MN titre ≥ 1 : 40) 1 year later. Children who received two doses of whole-virion vaccine had lower titres, although many were above the putative protective thresholds. One year after either pandemic vaccine, the 2010-11 trivalent seasonal influenza vaccine produced a marked serological response to the H1N1 component of the vaccine and was well tolerated. We propose to investigate whether or not previous receipt of monovalent influenza vaccines affected serological response to the H3N2 and B components of the 2010-11 seasonal influenza vaccine, using stored sera. TRIAL REGISTRATION: ClinicalTrials.gov NCT01239537. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Open-label, randomised, parallel-group, multicentre study to evaluate the safety, tolerability and immunogenicity of an AS03(B)/oil-in-water emulsion-adjuvanted (AS03(B)) split-virion versus non-adjuvanted whole-virion H1N1 influenza vaccine in UK children 6 months to 12 years of age.

OBJECTIVE: To evaluate the safety, tolerability and immunogenicity of an AS03(B)/oil-in-water emulsion-adjuvanted (AS03(B)) split-virion versus non-adjuvanted whole-virion H1N1 influenza vaccine in UK children aged 6 months to 12 years. DESIGN: Multicentre, randomised, head-to-head, open-label trial. SETTING: Five UK sites (Oxford, Bristol, Southampton, Exeter and London). PARTICIPANTS: Children aged 6 months to < 13 years, for whom a parent or guardian had provided written informed consent and who were able to comply with study procedures, were eligible for inclusion. INTERVENTIONS: A tocopherol/oil-in-water emulsion-adjuvanted (AS03(B)) egg culture-derived split-virion H1N1 vaccine and a non-adjuvanted cell culture-derived whole-virion vaccine, given as a two-dose schedule, 21 days apart, were compared. Participants were grouped into those aged 6 months to < 3 years (younger group) and 3 years to < 13 years of age (older group) and were randomised by study investigators (1 : 1 ratio) to receive one of the two vaccines. Vaccines were administered by intramuscular injection (deltoid or anterior-lateral thigh, depending on age and muscle bulk). Local reactions and systemic symptoms were collected for 1 week post immunisation, and serum was collected at baseline and after the second dose. To assess safety and tolerability, parents or guardians recorded the following information in diary cards from days 0-7 post vaccination: axillary temperature, injection site reactions, solicited and unsolicited systemic symptoms, and medications. MAIN OUTCOME MEASURE: Comparison between vaccines of the percentage of participants demonstrating seroconversion by microneutralisation assay. RESULTS: Among 937 children receiving vaccine, per-protocol seroconversion rates were higher after the AS03(B)-adjuvanted vaccine than after the whole-virion vaccine (98.2% vs 80.1% in children < 3 years, 99.1% vs 95.9% among those aged 3-12 years), as were severe local reactions (3.6% vs 0.0% in those under 5 years, 7.8% vs 1.1% in those aged 5-12 years), irritability in children < 5 years (46.7% vs 32.0%), and muscle pain in older children (28.9% vs 13.2%). The second dose of the adjuvanted vaccine was more reactogenic than the first, especially for fever > 38.0°C in those under 5 years of age (8.9% vs 22.4%). CONCLUSION: The adjuvanted vaccine, although reactogenic, was more immunogenic, especially in younger children, indicating the potential for improved immunogenicity of influenza vaccines in this age group. TRIAL REGISTRATION NUMBER: ISRCTN89141709.

Safety and immunogenicity of AS03B adjuvanted split virion versus non-adjuvanted whole virion H1N1 influenza vaccine in UK children aged 6 months-12 years: open label, randomised, parallel group, multicentre study.

OBJECTIVES: To compare the safety, reactogenicity, and immunogenicity of an adjuvanted split virion H1N1 vaccine and a non-adjuvanted whole virion vaccine used in the pandemic immunisation programme in the United Kingdom. DESIGN: Open label, randomised, parallel group, phase II study. SETTING: Five UK centres (Oxford, Southampton, Bristol, Exeter, and London). PARTICIPANTS: Children aged 6 months to less than 13 years for whom a parent or guardian had provided written informed consent and who were able to comply with study procedures were eligible. Those with laboratory confirmed pandemic H1N1 influenza or clinically diagnosed disease meriting antiviral treatment, allergy to egg or any other vaccine components, or coagulation defects, or who were severely immunocompromised or had recently received blood products were excluded. Children were grouped by age: 6 months-<3 years (younger group) and 3-<13 years (older group). Recruitment was by media advertising and direct mailing. Recruitment visits were attended by 949 participants, of whom 943 were enrolled and 937 included in the per protocol analysis. INTERVENTIONS: Participants were randomised 1:1 to receive AS03(B) (tocopherol based oil in water emulsion) adjuvanted split virion vaccine derived from egg culture or non-adjuvanted whole virion vaccine derived from cell culture. Both were given as two doses 21 days apart. Reactogenicity data were collected for one week after immunisation by diary card. Serum samples were collected at baseline and after the second dose. MAIN OUTCOME MEASURES: Primary reactogenicity end points were frequency and severity of fever, tenderness, swelling, and erythema after vaccination. Immunogenicity was measured by microneutralisation and haemagglutination inhibition assays. The primary immunogenicity objective was a comparison between vaccines of the percentage of participants showing seroconversion by the microneutralisation assay (fourfold rise to a titre of >or=1:40 from before vaccination to three weeks after the second dose). RESULTS: Seroconversion rates were higher after the adjuvanted split virion vaccine than after the whole virion vaccine, most notably in the youngest children (163 of 166 participants with paired serum samples (98.2%, 95% confidence interval 94.8% to 99.6%) v 157 of 196 (80.1%, 73.8% to 85.5%), P<0.001) in children under 3 years and 226 of 228 (99.1%, 96.9% to 99.9%) v 95.9%, 92.4% to 98.1%, P=0.03) in those over 3 years). The adjuvanted split virion vaccine was more reactogenic than the whole virion vaccine, with more frequent systemic reactions and severe local reactions in children aged over 5 years after dose one (13 (7.2%, 3.9% to 12%) v 2 (1.1%, 0.1% to 3.9%), P<0.001) and dose two (15 (8.5%, 4.8% to 13.7%) v 2 (1.1%, 0.1% to 4.1%), P<0.002) and after dose two in those under 5 years (15 (5.9%, 3.3% to 9.6%) v 0 (0.0%, 0% to 1.4%), P<0.001). Dose two of the adjuvanted split virion vaccine was more reactogenic than dose one, especially for fever >or=38 masculineC in those aged under 5 (24 (8.9%, 5.8% to 12.9%) v 57 (22.4%, 17.5% to 28.1%), P<0.001). CONCLUSIONS: In this first direct comparison of an AS03(B) adjuvanted split virion versus whole virion non-adjuvanted H1N1 vaccine, the adjuvanted vaccine, while more reactogenic, was more immunogenic and, importantly, achieved high seroconversion rates in children aged less than 3 years. This indicates the potential for improved immunogenicity of influenza vaccines in this age group. TRIAL REGISTRATION: Clinical trials.gov NCT00980850; ISRCTN89141709.

Observational study to investigate vertically acquired passive immunity in babies of mothers vaccinated against H1N1v during pregnancy.

OBJECTIVE: The primary objective was to determine the proportion of babies who acquired passive immunity to A/H1N1v, born to mothers who accepted vaccination as part of the national vaccination programme while pregnant (during the second and/or third trimesters) against the novel A/H1N1v influenza virus (exposed group) compared with unvaccinated (unexposed) mothers. DESIGN: An observational study at three sites in the UK. The purpose was to determine if mothers immunised against A/H1N1v during the pandemic vaccination period transferred that immunity to their child in utero. SETTING: Three sites in the UK [Queen's Medical Centre, Nottingham; City Hospital, Nottingham (both forming University Hospitals Nottingham), and Leicester Royal Infirmary (part of University Hospitals Leicester)]. PARTICIPANTS: All pregnant women in the second and third trimester presenting at the NHS hospitals above to deliver were eligible to participate in the study. Women were included regardless of age, social class, ethnicity, gravida and parity status, past and current medical history (including current medications), ethnicity, mode of delivery and pregnancy outcome (live/stillbirth). INTERVENTIONS: At enrolment, participants provided written consent and completed a questionnaire. At parturition, venous cord blood was obtained for serological antibody analysis. Serological analysis was undertaken by the Respiratory Virus Unit (RVU), Health Protection Agency (HPA) Centre for Infections, London. MAIN OUTCOME MEASURES: The primary end point in the study was the serological results of the cord blood samples for immunity to A/H1N1v. Regarding a suitable threshold for the determination of a serological response consistent with clinical protection, this issue is somewhat complex for pandemic influenza. The European Medicines Agency (EMEA) Committee for Human Medicinal Products (CHMP) judges that a haemagglutination inhibition (HI) titre of 1 : 40 is an acceptable threshold. However, this level was set in the context of licensing plain trivalent seasonal vaccine, where a titre of 1 : 40 is but one of several related immunogenicity criteria, and supported by paired sera capable of demonstrating a fourfold rise in antibody titre in response to vaccination. The current study mainly investigated the effects of an AS03-adjuvanted monovalent vaccine, and it was not possible to obtain paired sera where the initial sample was taken before vaccination (in vaccinated subjects). Of possibly greater relevance is the fact that it has been established from the study of early outbreaks of pandemic influenza in secondary schools in the UK (HPA, unpublished observations) that an HI antibody titre of 1 : 32 seems to be the threshold for a humoral response to 'wild-type' A/H1N1v infection. On that basis, a threshold of 1 : 32 is at least as appropriate as one of 1 : 40, especially in unvaccinated individuals. Given the difficulties that would accrue by applying thresholds of 1 : 32 in unvaccinated patients and 1 : 40 in vaccinated patients, we have therefore applied a threshold of 1 : 32 and 1 : 40, to increase the robustness of our findings. Differences arising are described. A microneutralisation (MN) titre of 1 : 40 may be also used, although it is not part of the CHMP criteria for vaccine licensure. Nonetheless, we utilised this analysis as a secondary end point, based on a conservative threshold of 1 : 60. RESULTS: Reverse cumulative distribution percentage curves for haemagglutinin dilution and MN titres demonstrate background immunity in babies of unvaccinated mothers of 25%-30%. Humoral immunity in babies of vaccinated mothers was present in 80% of the group. The difference in positive immunity between the babies of unvaccinated and vaccinated mothers was statistically significant (chi-squared test, p < 0.001). CONCLUSIONS: Our findings reveal a highly significant difference in HI titres between babies born to mothers vaccinated with pandemic-specific vaccine against A/H1N1v during the 2009-10 pandemic period. The subjects recruited were comparable from a baseline perspective and thus do not represent different groups that otherwise could have introduced bias into the study. Continued circulation of 2009 A/H1N1-like viruses is uncertain, but is possible as seasonal influenza in years to come. It is possible that future seasonal waves may display increased virulence. Given the adverse outcomes experienced for a small proportion of pregnant women during the influenza pandemic of 2009-10, this study provides useful evidence to support vaccination in pregnancy to protect both the mother and baby. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Assessment of baseline age-specific antibody prevalence and incidence of infection to novel influenza A/H1N1 2009.

OBJECTIVES: The objectives of the H1N1 2009 serological surveillance project were twofold: to document (1) the prevalence of cross-reactive antibodies to H1N1 2009 by age group in the population of England prior to arrival of the pandemic strain virus in the UK and (2) the age-specific incidence of infection by month as the pandemic progressed by measuring increases in the proportion of individuals with antibodies to H1N1 2009 by age. METHODS: Residual aliquots of samples submitted to 16 microbiology laboratories in eight regions in England in defined age groups in 2008 and stored by the Health Protection Agency serological surveillance programme were used to document age-stratified prevalence of antibodies to H1N1 2009 prior to the arrival of the pandemic in the UK. Functional antibodies to the H1N1 2009 virus were measured by haemagglutination inhibition (HI) and microneutralisation (MN) assays. For timely measurement of monthly incidence of infection with H1N1 2009 between August 2009 and April 2010, the microbiology serum collections were supplemented by collection of residual sera from chemical pathology laboratories in England. Monthly seroincidence samples were tested by HI only, apart from the final sera collected post pandemic in 2010, which were also tested by MN. Incidence during the pandemic was estimated from changes in prevalence between time points and also by a likelihood-based method. SETTING: Eight regions of England. PARTICIPANTS: Serum samples from patients accessing health care in England from whom blood samples were taken for unrelated microbiological or chemical pathology testing. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Baseline age-specific prevalence of functional antibodies to the H1NI 2009 virus prior to the arrival of the pandemic; changes in antibody prevalence during the period August 2009 to April 2010. RESULTS: Pre-existing cross-reactive antibodies to H1N1 2009 were detected in the baseline sera and increased with age, particularly in those born before 1950. The prediction of immunological protection derived from the baseline serological analysis was consistent with the lower clinical attack rates in older age groups. The high levels of susceptibility in children < 15 years, together with their mixing within school, resulted in the highest attack rates in this age group. Serological analysis by region confirms that there were geographical differences in timing of major pandemic waves. London had a big first wave among the 5- to 14-year age group, with the rest of the country reducing the gap after the second wave. Cumulative incidence in London remained higher throughout the pandemic in each age group. By the end of the second wave it is estimated that as many as 70% of school-aged children in London had been infected. Taken together, these observations are consistent with observations from previous pandemics in 1918, 1957 and 1968 - that the major impact of influenza pandemics is on younger age groups, with a pattern of morbidity and mortality distinct from seasonal influenza epidemics. CONCLUSIONS: Serological analysis of appropriately structured, age-stratified and geographically representative samples can provide an immense amount of information to set in context other measures of pandemic impact in a population, and provide the most accurate measures of population exposure. National scale seroepidemiology studies require cross-agency coordination, multidisciplinary working, and considerable scientific resource. FUNDING: The National Institute for Health Research Health Technology Assessment programme and the Health Protection Agency.

A randomised, partially observer blind, multicentre, head-to-head comparison of a two-dose regimen of Baxter and GlaxoSmithKline H1N1 pandemic vaccines, administered 21 days apart.

OBJECTIVES: To evaluate the immunogenicity of a two-dose schedule of Baxter cell-cultured, non-adjuvanted, whole-virion H1N1 vaccine, and GlaxoSmithKline AS03(A)-adjuvanted split-virion H1N1 vaccine with respect to the EU Committee for Medicinal Products for Human Use (CHMP) and the US Food and Drug Administration (FDA) licensing criteria. DESIGN: An age-stratified, randomised, observer-blind, parallel-group, multicentre controlled trial was carried out in volunteers aged ≥ 18-44, ≥ 45-64 and ≥ 65 years. SETTING: Three teaching hospitals in the UK (Leicester Royal Infirmary, Leicester; Nottingham City Hospital, Nottingham; and Royal Hallamshire Hospital, Sheffield). PARTICIPANTS: Three hundred and forty-seven subjects were identified and randomised to AS03(A)-adjuvanted split-virion H1N1 vaccine or whole-virion (WV) vaccine in age groups [≥ 18-44 years (n = 140), ≥ 45-64 years (n = 136) and ≥ 65 years (n = 71)]. INTERVENTIONS: Vaccine was administered by intramuscular injection into the deltoid muscle of the non-dominant arm. One hundred and seventy-five randomised subjects were allocated AS03(A)-adjuvanted split H1N1 vaccine; one hundred and sixty-nine subjects had a second dose of the same vaccine 21 days later. One hundred and seventy-two subjects were allocated WV vaccine; one hundred and seventy-one subjects had a second dose of the same vaccine 21 days later. Serum samples for antibody measurements were collected on days 0 (before the first vaccination), 7, 14, 21 (before the second vaccination), 28, 35, 42 and 180. Subjects were observed for local and systemic reactions for 30 minutes after each injection, and for the next 7 days they recorded, in self-completed diaries, the severity of solicited local (pain, bruising, erythema and swelling) and systemic symptoms (chills, malaise, muscle aches, nausea and headache), oral temperature and use of analgesic medications. MAIN OUTCOME MEASURES: Vaccine immunogenicity using the CHMP and the FDA licensing criteria. Antibody titres were measured using haemagglutination inhibition (HI) and microneutralisation (MN) assays at baseline and 7, 14 and 21 days after each vaccination and at day 180. The three immunogenicity criteria end points were the seroprotection rate, the seroconversion rate and the mean-fold titre elevation. RESULTS: Both vaccine doses were given in 340 subjects (98%). Data from 680 (99%) of 687 issued diary cards were returned. Sera were obtained from 340 (98.0%), 333 (96.0%), 341 (98.3%), 331 (95.4%), 329 (94.8%) and 332 (95.7%) subjects on days 7, 14, 21, 28, 35 and 42, respectively. Three hundred and forty-six and 345 subjects were included in the safety and immunogenicity analyses, respectively. Prevaccination antibody was detected by HI (titre ≥ 1 : 8) and MN (titre ≥ 1 : 10) in 14% and 31% of subjects, respectively. Among the 298 (85.9%) subjects without baseline antibody on HI assay, a titre of ≥ 1 : 40 (seroprotection) was achieved after a single dose of AS03(A)-adjuvanted vaccine and WV vaccine by day 21 in 93.0% and 65.5%, respectively, of subjects between 18 and 44 years, 76.4% and 36.1% of subjects between 45 and 64 years, and 53.1% and 30.0% of subjects ≥ 65 years. Among all 347 subjects, a titre of ≥ 1 : 40 was achieved after a single dose of AS03(A)-adjuvanted vaccine and WV vaccine by day 21 in 94.0% and 71.4%, respectively, of subjects between 18 and 44 years, 77.3% and 38.8% of subjects between 45 and 64 years, and 51.4% and 32.4% of subjects ≥ 65 years. The age-adjusted odds ratio (OR) for adjuvanted compared with WV vaccine, in terms of seroprotection, was 4.42 [95% confidence interval (CI) 2.63 to 7.44, p < 0.001]. On day 42, among subjects without baseline antibody on HI assay, a titre of ≥ 1 : 40 was achieved after the second dose of AS03(A)-adjuvanted vaccine and WV vaccine by 100% and 67.9%, respectively, of subjects between 18 and 44 years, 89.3% and 41% of subjects between 45 and 64 years, and 76.5% and 34.5% of subjects ≥ 65 years. Among all 347 subjects, a titre of ≥ 1 : 40 was achieved on day 42 after the second dose of AS03(A)-adjuvanted vaccine and WV vaccine in 100% and 73.1%, respectively, of subjects between 18 and 44 years, 90.8% and 43.9% of subjects between 45 and 64 years, and 75.7% and 36.4% of subjects ≥ 65 years. The age-adjusted OR for adjuvanted vaccine compared with WV vaccine, in terms of seroprotection, was 11.21 (95% CI 5.80 to 21.64, p < 0.001). Age-related decline in antibody response occurred after both doses of both vaccines. WV vaccine was associated with fewer local and systemic reactions and lower immune responses than was AS03(A)-adjuvanted vaccine. The most frequent solicited local event was pain, reported by 28% and 76% of subjects after either dose of WV or adjuvanted vaccine, respectively (OR 7.71, 95% CI 4.48 to 13.24, p < 0.0001). The most common systemic event was myalgia, reported by 24% and 49% of subjects after either dose of WV or adjuvanted vaccine (OR 2.99, 95% CI 1.86 to 4.80, p < 0.0001). CONCLUSIONS: AS03(A)-adjuvanted 2009 H1N1 vaccine is more immunogenic and provides greater antigen-sparing capacity than WV 2009 H1N1 vaccine. TRIAL REGISTRATION: Current Controlled Trials ISRCTN92328241. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 14, No. 55. See the HTA programme website for further project information.

No evidence of transmission of H5N1 highly pathogenic avian influenza to humans after unprotected contact with infected wild swans.

Highly pathogenic avian influenza (HPAI) subtype H5N1 remains a public health threat as long as it circulates in wild and domestic birds. Information on the transmissibility of H5N1 HPAI from wild birds is needed for evidence-based public health advice. We investigated if transmission of H5N1 HPAI had taken place in people that had unprotected contact with infected wild mute swans during an incident at the Abbotsbury Swannery in Dorset, England. Thirteen people who had been exposed to infected swans were contacted and actively followed up for symptoms. Serology was taken after 30 days. We did not find evidence of transmission of H5N1 HPAI to humans during the incident. The incident provided a rare opportunity to study the transmissibility of the virus from wild birds to humans.

Structural analysis of an RNase T1 variant with an altered guanine binding segment.

The ribonuclease T1 variant 9/5 with a guanine recognition segment, altered from the wild-type amino acid sequence 41-KYNNYE-46 to 41-EFRNWQ-46, has been cocrystallised with the specific inhibitor 2'-GMP. The crystal structure has been refined to a crystallographic R factor of 0.198 at 2.3 A resolution. Despite a size reduction of the binding pocket, pushing the inhibitor outside by 1 A, 2'-GMP is fixed to the primary recognition site due to increased aromatic stacking interactions. The phosphate group of 2'-GMP is located about 4.2 A apart from its position in wild-type ribonuclease T1-2'-GMP complexes, allowing a Ca(2+), coordinating this phosphate group, to enter the binding pocket. The crystallographic data can be aligned with the kinetic characterisation of the variant, showing a reduction of both, guanine affinity and turnover rate. The presence of Ca(2+) was shown to inhibit variant 9/5 and wild-type enzyme to nearly the same extent.