Maria Zambon

Incidence of 2009 pandemic influenza A H1N1 infection in England: a cross-sectional serological study

BACKGROUND Knowledge of the age-specific prevalence of immunity from, and incidence of infection with, 2009 pandemic influenza A H1N1 virus is essential for modelling the future burden of disease and the effectiveness of interventions such as vaccination. METHODS In this cross-sectional serological survey, we obtained 1403 serum samples taken in 2008 (before the first wave of H1N1 infection) and 1954 serum samples taken in August and September, 2009 (after the first wave of infection) as part of the annual collection for the Health Protection Agency seroepidemiology programme from patients accessing health care in England. Antibody titres were measured by use of haemagglutination inhibition and microneutralisation assays. We calculated the proportion of samples with antibodies to pandemic H1N1 virus in 2008 by age group and compared the proportion of samples with haemagglutination inhibition titre 1:32 or more (deemed a protective response) before the first wave of infection with the proportion after the first wave. FINDINGS In the baseline serum samples from 2008, haemagglutination inhibition and microneutralisation antibody titres increased significantly with age (F test p<0.0001). The proportion of samples with haemagglutination inhibition titre 1:32 or more ranged from 1.8% (three of 171; 95% CI 0.6-5.0) in children aged 0-4 years to 31.3% (52 of 166; 24.8-38.7) in adults aged 80 years or older. In London and the West Midlands, the difference in the proportion of samples with haemagglutination inhibition titre equal to or above 1:32 between baseline and September, 2009, was 21.3% (95% CI 8.8-40.3) for children younger than 5 years of age, 42.0% (26.3-58.2) for 5-14-year-olds, and 20.6% (1.6-42.4) for 15-24-year-olds, with no difference between baseline and September in older age groups. In other regions, only children younger than 15 years showed a significant increase from baseline (6.3%, 1.8-12.9). INTERPRETATION Around one child in every three was infected with 2009 pandemic H1N1 in the first wave of infection in regions with a high incidence, ten times more than estimated from clinical surveillance. Pre-existing antibody in older age groups protects against infection. Children have an important role in transmission of influenza and would be a key target group for vaccination both for their protection and for the protection of others through herd immunity. FUNDING National Institute for Health Research Health Technology Assessment Programme.

Newly discovered coronavirus as the primary cause of severe acute respiratory syndrome

Summary Background The worldwide outbreak of severe acute respiratory syndrome (SARS) is associated with a newly discovered coronavirus, SARS-associated coronavirus (SARSCoV). We did clinical and experimental studies to assess the role of this virus in the cause of SARS. Methods We tested clinical and postmortem samples from 436 SARS patients in six countries for infection with SARSCoV, human metapneumovirus, and other respiratory pathogens. We infected four cynomolgus macaques (Macaca fascicularis) with SARS-CoV in an attempt to replicate SARS and did necropsies on day 6 after infection. Findings SARS-CoV infection was diagnosed in 329 (75%) of 436 patients fitting the case definition of SARS; human metapneumovirus was diagnosed in 41 (12%) of 335, and other respiratory pathogens were diagnosed only sporadically. SARS-CoV was, therefore, the most likely causal agent of SARS. The four SARS-CoV-infected macaques excreted SARS-CoV from nose, mouth, and pharynx from 2 days after infection. Three of four macaques developed diffuse alveolar damage, similar to that in SARS patients, and characterised by epithelial necrosis, serosanguineous exudate, formation of hyaline membranes, type 2 pneumocyte hyperplasia, and the presence of syncytia. SARS-CoV was detected in pneumonic areas by virus isolation and RT-PCR, and was localised to alveolar epithelial cells and syncytia by immunohistochemistry and transmission electron microscopy. Interpretation Replication in SARS-CoV-infected macaques of pneumonia similar to that in human beings with SARS, combined with the high prevalence of SARS-CoV infection in SARS patients, fulfill the criteria required to prove that SARS-CoV is the primary cause of SARS. Published online July 22, 2003 http://image.thelancet.com/extras/03art6318web.pdf

Safety and antigenicity of non-adjuvanted and MF59-adjuvanted influenza A/Duck/Singapore/97 (H5N3) vaccine : a randomised trial of two potential vaccines against H5N1 influenza

BACKGROUND In 1997, pathogenic avian influenza A/Hong Kong/97 (H5N1) viruses emerged as a pandemic threat to human beings. A non-pathogenic variant, influenza A/Duck/Singapore/97 (H5N3), was identified as a leading vaccine candidate. We did an observer-blind, phase I, randomised trial in healthy volunteers to assess safety, tolerability, and antigenicity of MF59-adjuvanted and non-adjuvanted vaccines. METHODS 32 participants were randomly assigned MF59, and 33 non-adjuvanted vaccine. Two doses were given 3 weeks apart, of 7.5, 15, or 30 microg haemagglutinin surface-antigen influenza A H5N3 vaccine. Antibody responses were measured by haemagglutination inhibition, microneutralisation, and single radial haemolysis (SRH). The primary outcome was geometric mean antibody titre 21 days after vaccination. FINDINGS The A/Duck/SIngapore vaccines were safe and well tolerated. Antibody response to non-adjuvanted vaccine was poor, the best response occurring after two 30 microgram doses: one, four, four, and one person of eleven seroconverted by haemagglutination inhibition, microneutralisation, H5N3 SRH, and H5N1 SRH, respectively. The geometric mean titres of antibody, and seroconversion rates, were significantly higher after MF59 adjuvanted vaccine. Two 7.5 microg doses of MF59 adjuvanted vaccine gave the highest seroconversion rates: haemagglutination inhibition, six of ten; microneutralisation, eight of ten; H5N3 SRH, ten of ten; H5N1 SRH, nine of ten. Geometric mean titre of antibody to the pathogenic virus, A/Hong Kong/489/97 (H5N1), was about half that to A/Duck/Singapore virus. INTERPRETATION Non-adjuvanted A/Duck/Singapore/97 (H5N3) vaccines are poorly immunogenic and doses of 7.5-30 microg haemagglutinin alone are unlikely to give protection from A/Hong Kong/97 (H5N1) virus. Addition of MF59 to A/Duck/Singapore/97 vaccines boost the antibody response to protection levels. Our findings have implications for development and assessment of vaccines for future pandemics.

Safety and immunogenicity of an inactivated split-virion influenza A/Vietnam/1194/2004 (H5N1) vaccine: phase I randomised trial

BACKGROUND Pathogenic avian influenza A virus H5N1 has caused outbreaks in poultry and migratory birds in Asia, Africa, and Europe, and caused disease and death in people. Although person-to-person spread of current H5N1 strains is unlikely, the virus is a potential source of a future influenza pandemic. Our aim was to assess the safety and immunogenicity of a vaccine against the H5N1 strain. METHODS We did a randomised, open-label, non-controlled phase I trial in 300 volunteers aged 18-40 years and assigned one of six inactivated split influenza A/Vietnam/1194/2004 (H5N1) influenza vaccine formulations, comprising 7.5 microg (with adjuvant n=50, without adjuvant n=49), 15 microg (n=50, n=50), or 30 microg (n=51, n=50) of haemagglutinin with or without aluminium hydroxide adjuvant. Individuals received two vaccinations (on days 0 and 21) and provided blood samples (on days 0, 21, and 42) for analysis by haemagglutination inhibition and microneutralisation. We recorded all adverse events. Analyses were descriptive. FINDINGS All formulations were well tolerated, with no serious adverse events, few severe reactions, and no oral temperatures of more than 38 degrees C. All formulations induced an immune response, and responses were detectable in some individuals after only one dose. The adjuvanted 30 microg formulation induced the greatest response (67% haemagglutinin-inhibition seroconversion rate after two vaccinations). Adjuvant did not improve the response to the lower doses. Two vaccinations of non-adjuvanted 7.5 microg, adjuvanted 15 microg, or non-adjuvanted 15 microg seroconverted more than 40% of participants (haemagglutinin-inhibition test only). Haemagglutinin inhibition and neutralising results were comparable. INTERPRETATION A two-dose regimen with an adjuvanted 30 microg inactivated H5N1 vaccine was safe and showed an immune response consistent with European regulatory requirements for licensure of seasonal influenza vaccine. We noted encouraging responses with lower doses of antigen that need further study to ascertain their relevance for the choice of the final pandemic vaccine.

Middle East Respiratory Syndrome Coronavirus (MERS-CoV); Announcement of the Coronavirus Study Group

During the summer of 2012, in Jeddah, Saudi Arabia, a hitherto unknown coronavirus (CoV) was isolated from the sputum of a patient with acute pneumonia and renal failure ([1][1], [2][2]). The isolate was provisionally called human coronavirus Erasmus Medical Center (EMC) ([3][3]). Shortly thereafter

Contribution of influenza and respiratory syncytial virus to community cases of influenza-like illness: an observational study

BACKGROUND Respiratory syncytial virus (RSV) is an important cause of lower-respiratory-tract infection in children and elderly people, but its effect in other age-groups is uncertain. We did a community-based observational study of RSV infection in community-dwelling individuals of all ages who presented to general practices in the UK with influenza-like illnesses during three successive winters (1995-96, 1996-97, and 1997-98). METHODS Nasopharyngeal swabs routinely submitted for virological surveillance were examined by multiplex reverse transcription PCR for influenza A and B viruses and RSV A and B, and findings were related to the clinical incidence of influenza-like illness and acute bronchitis at that time. RSV strains identified were compared with those obtained from hospital admissions. FINDINGS 480 RSV and 709 influenza viruses were identified from a total of 2226 swabs submitted. Both types of virus were found in all age-groups for between 12 and 20 weeks in each winter. RSV A accounted for 60% of RSV detections. Similar strains of RSV were present in hospital and community patients within the same year, but there were different lineages each year. INTERPRETATION In individuals diagnosed with influenza-like illness, there is a substantial potential for confusion between illnesses caused by influenza and those caused by RSV. The burden of illness attributable to each needs to be clarified to define optimum management routines.

Oseltamivir-resistant influenza virus A (H1N1), Europe, 2007/08 season.

A high level of virus circulation and introduction of an antigenic drift variant in a susceptible population contributed to the spread of resistant virus.

Detection of Influenza Viruses Resistant to Neuraminidase Inhibitors in Global Surveillance during the First 3 Years of Their Use

ABSTRACT Emergence of influenza viruses with reduced susceptibility to neuraminidase inhibitors (NAIs) develops at a low level following drug treatment, and person-to-person transmission of resistant virus has not been recognized to date. The Neuraminidase Inhibitor Susceptibility Network (NISN) was established to follow susceptibility of isolates and occurrence of NAI resistance at a population level in various parts of the world. Isolates from the WHO influenza collaborating centers were screened for susceptibilities to oseltamivir and zanamivir by a chemiluminescent enzyme inhibition assay, and those considered potentially resistant were analyzed by sequence analysis of the neuraminidase genes. During the first 3 years of NAI use (1999 to 2002), 2,287 isolates were tested. Among them, eight (0.33%) viruses had a >10-fold decrease in susceptibility to oseltamivir, one (0.22%) in 1999 to 2000, three (0.36%) in 2000 to 2001, and four (0.41%) in 2001 to 2002. Six had unique changes in the neuraminidase gene compared to neuraminidases of the same subtype in the influenza sequence database. Although only one of the mutations had previously been recognized in persons receiving NAIs, none were from patients who were known to have received the drugs. During the 3 years preceding NAI use, no resistant variants were detected among 1,054 viruses. Drug use was relatively stable during the period, except for an approximate 10-fold increase in oseltamivir use in Japan during the third year. The frequency of variants with decreased sensitivity to the NAIs did not increase significantly during this period, but continued surveillance is required, especially in regions with higher NAI use.

Cross-Reactivity to Highly Pathogenic Avian Influenza H5N1 Viruses after Vaccination with Nonadjuvanted and MF59-Adjuvanted Influenza A/Duck/Singapore/97 (H5N3) Vaccine: A Potential Priming Strategy

Antigenically well-matched vaccines against highly pathogenic avian influenza H5N1 viruses are urgently required. Human serum samples after immunization with MF59 or nonadjuvanted A/duck/Singapore/97 (H5N3) vaccine were tested for antibody to 1997-2004 human H5N1 viruses. Antibody responses to 3 doses of nonadjuvanted vaccine were poor and were higher after MF59-adjuvanted vaccine, with seroconversion rates to A/HongKong/156/97, A/HongKong/213/03, A/Thailand/16/04, and A/Vietnam/1203/04 of 100% (P < .0001), 100% (P < .0001), 71% (P = .0004), and 43% (P = .0128) in 14 subjects, respectively, compared with 27%, 27%, 0%, and 0% in 11 who received nonadjuvanted vaccine. These findings have implications for the rational design of pandemic vaccines against influenza H5.

Human Metapneumovirus as a Cause of Community-Acquired Respiratory Illness

Human metapneumovirus (HMPV) is a recently identified Paramyxovirus first isolated from hospitalized children with acute respiratory tract infections (ARTI). We sought evidence of HMPV infection in patients who had visited general practitioners, had influenzalike illnesses (ILI), and had negative tests for influenza and Human respiratory syncytial virus (HRSV). As part of national virologic surveillance, sentinel general practices in England and Wales collected samples from patients of all ages with ILI during winter 2000–01. Reverse transcriptase-polymerase chain reaction (PCR) for HMPV, influenza A (H1 and H3), influenza B, and HRSV was used to screen combined nose and throat swabs. PCR products from the HMPV-positive samples were sequenced to confirm identity and construct phylogenetic trees. Of 711 swabs submitted, 408 (57.3%) were negative for influenza and HRSV; HMPV was identified in 9 (2.2%) patients. HMPV appears to be associated with community-acquired ARTI. The extent of illness and possible complications related to this new human virus need to be clarified