To determine influenza vaccine effectiveness against clinically defined influenza-like illness among Malaysian pilgrims attending the Haj in Saudi Arabia.
Numerous lessons have been learned so far in controlling H5N1 avian influenza in Asia. Early detection of incursions of virus prevented establishment of the disease in several countries, notably Japan, South Korea, and Malaysia. In countries where detection of early cases was delayed, infection is endemic and has been for three or more years. Control measures implemented in these countries need to reflect this finding. Vaccination will continue to be one of the key measures used in these endemically infected countries. Used alone, vaccination will not result in elimination of H5N1 viruses from a country, but, if used correctly, it will markedly reduce the prevalence of and susceptibility to infection. Vaccination has already played a valuable role in reducing the adverse effects of H5N1 viruses. Mass culling also reduces the level of infection in infected areas. However, the long-term benefits are limited in endemically infected countries owing to the high probability of reinfection on restocking unless other measures are used in parallel. Full epidemiological studies have not been conducted in many infected countries. Nevertheless, it is recognized that the number of clinical cases does not truly reflect the levels of infection. Domestic ducks and large live poultry markets have played a key role in the persistence of infection, because they can be infected silently. In tackling this disease, countries should adopt integrated control programs using the combination of measures best suited to the local environment. All surveillance data should be shared, both positive and negative, and should include information on cases of infection and disease. Socioeconomic and ecological implications of all control measures should be assessed before implementation, especially the impact on the rural poor.
The aims of the study were to determine the attack rate of influenza-like illness among inhabitants of five old folk homes nationwide using influenza vaccine as a probe and the effectiveness of influenza vaccination in prevention of influenza-like illness. We conducted a nonrandomized, single-blind placebo control study from June 2003 to February 2004. VAXIGRIP(R) 2003 Southern hemisphere formulation was used. Among 527 subjects, the attack rates of influenza-like illness in the influenza vaccine group were 6.4, 4.6 and 2.4% during the first, second and third 2-month periods, respectively. The attack rates of influenza-like illness in the placebo group were 17.7, 13.8 and 10.1%. Influenza vaccination reduced the risk of contracting influenza-like illness by between 14, and 45%. The vaccine effectiveness in reducing the occurrence of influenza-like illness ranged from 55 to 76%, during the 6-month study followup. The presence of cerebrovascular diseases significantly increased the risk of influenza-like illness (p < 0.005). Vaccine recipients had fewer episodes of fever, cough, muscle aches, runny nose (p < 0.001) and experience fewer sick days due to respiratory illness. Subjects who received influenza vaccination had clinically and statistically significant reductions in the attack rate of influenza-like illness. Our data support influenza vaccination of persons with chronic diseases and >50 year olds living in institutions.
The influenza epidemic of 2006/'07 began late in the season, like the two previous influenza epidemics. In week 8 a peak of modest height was reached. As usual, the causal strains were mainly A/H3N2 viruses and to a lesser extent A/H1N1 and B viruses. A new A/H1N1 virus variant has emerged, an event that on average takes place only every 10 years. However, almost all A/H1N1 virus isolates belonged to the old variant and were similar to the vaccine virus. The A/H3N2 virus isolates appeared to deviate from the vaccine strain, but after antigenic cartographic analysis and correction for low avidity they proved also closely related to the vaccine strain. The few type B virus isolates belonged to the B/Yamagata/16/88 lineage, whereas the used B vaccine virus had been chosen from the B/Victoria/2/87 lineage. The vaccine therefore will have provided almost optimal protection against the circulating influenza A/H1N1 and A/H3N2 viruses but not against the influenza B viruses. For the 2007/'08 influenza season the World Health Organization has recommended the following vaccine composition: A/Solomon Islands/3/06 (H1N1) (new), A/Wisconsin/67/05 (H3N2), and B/Malaysia/2506/04.
Trivalent inactivated influenza vaccine (TIV) is reformulated annually to contain representative strains of 2 influenza A subtypes (H1N1 and H3N2) and 1 B lineage (Yamagata or Victoria). We describe a sentinel surveillance approach to link influenza variant detection with component-specific vaccine effectiveness (VE) estimation.
Despite the established benefit of intramuscular (i.m.) influenza vaccination, new adjuvants and delivery methods for comparable or improved immunogenicity are being explored. Intradermal (i.d.) antigen administration is hypothesized to initiate an efficient immune response at reduced antigen doses similar to that observed after i.m. full dose vaccination.
This study evaluated whether MF59-adjuvanted subunit trivalent influenza vaccine for the 2003/04 winter season (A/Moscow/10/99, H3N2; A/New Caledonia/20/99, H1N1; B/Hong Kong/330/01) would confer protection against mismatched and frequently co-circulating variants of influenza B/Victoria- and B/Yamagata-like virus strains. Haemagglutination inhibiting (HI) antibodies were measured in middle-aged and elderly volunteers against the homologous B/Victoria-like vaccine strain (B/Hong Kong/330/01) and against mismatched B/Victoria-like (B/Malaysia/2506/04) and B/Yamagata-like (B/Singapore/379/99 and B/Shanghai/361/02) strains. Immunization induced significant increases in the amounts of HI antibodies against all influenza B strains under investigation. However, the responses against the heterologous B/Shanghai/361/02 virus did not reach the desirable values of seroprotection. An age-dependent decline of the responses was found for B/Victoria-like antigens, but not for B/Yamagata-like strains. Although further studies are needed, our data support the recommendation of including influenza B viruses of the B/Victoria and B/Yamagata lineages in the future influenza vaccine preparations.
The immunogenicity and tolerability of virosome and of split influenza vaccines in patients with sickle cell anemia (SS) were evaluated. Ninety SS patients from 8 to 34 years old were randomly assigned to receive either virosome (n=43) or split vaccine (n=47). Two blood samples were collected, one before and one 4-6 weeks after vaccination. Antibodies against viral strains (2006) A/New Caledonia (H1N1), A/California (H3N2), B/Malaysia were determined using the hemagglutinin inhibition test. Post-vaccine reactions were recorded over 7 days. Seroconversion rates for H1N1, H3N2 and B were 65.1%, 60.4% and 83.7% for virosome vaccine, and 68.0%, 61.7% and 68.0% for split vaccine. Seroprotection rates for H1N1, H3N2 e B were 100%, 97.6% and 69.7% for virosome, and 97.8%, 97.8% and 76.6% for split vaccine. No severe adverse reactions were recorded. Virosome and split vaccines in patients with sickle cell anemia were equally immunogenic, with high seroconversion and seroprotection rates. Both vaccines were well tolerated.
Several critical factors of an influenza microneutralization assay, utilizing a rapid biotin-streptavidin conjugated system for detecting influenza virus subtypes A and B, are addressed within this manuscript. Factors such as incubation times, amount of virus, cell seeding, sonication, and TPCK trypsin were evaluated for their ability to affect influenza virus neutralization in a microplate-based neutralization assay using Madin-Darby canine kidney (MDCK) cells. It is apparent that the amount of virus used in the assay is the most critical factor to be optimized in an influenza microneutralization assay. Results indicate that 100xTCID(50) of influenza A/Solomon Islands/03/2006 (H1N1) virus overloads the assay and results in no, to low, neutralization, in both ferret and macaque sera, respectively, whereas using 6xTCID(50) resulted in significantly improved neutralization. Conversely, strong neutralization was observed against 100xTCID(50) of B/Malaysia/2506/04 virus. In this manuscript the critical factors described above were optimized and the results indicate that the described biotin-streptavidin conjugated influenza microneutralization assay is a rapid and robust method for detecting the presence of functional, influenza virus-neutralizing antibodies.
Children aged 11 to <24 months received 2 intranasal doses of live attenuated influenza vaccine (LAIV) or placebo, 35+/-7 days apart. Dose 1 was administered concomitantly with a combined measles, mumps, and rubella vaccine (Priorix). Seroresponses to measles and mumps were similar between groups. Compared with placebo, response rates to rubella in LAIV+Priorix recipients were statistically lower at a 15 IU/mL threshold (83.9% vs 78.0%) and the prespecified noninferiority criteria were not met. In a post hoc analysis using an alternate widely accepted threshold of 10 IU/mL, the noninferiority criteria were met (93.4% vs 89.8%). Concomitant administration with Priorix did not affect the overall influenza protection rate of LAIV (78.4% and 63.8% against antigenically similar influenza strains and any strain, respectively).
In a short period of two months, the novel influenza A/H1N1 virus has circumnavigated the entire planet leaving behind in its wake approximately 3000 reported deaths worldwide. Fortunately, in many areas around the world, September 2009 brought a lull in the number of new H1N1 infections. This brought welcomed relief in many countries that had earlier experienced high respiratory disease activity in their communities. However, based on previous influenza pandemics, this reprieve may well be short-lived. As the Northern hemisphere approaches its winter months, many experts are now predicting a second wave of influenza A/H1N1 infections. This prediction maybe well placed as all 3 influenza pandemics in the last century reported second or even subsequent waves of new infections, all of which appeared to be more severe than the primary event (ref). The timing of these second waves have varied from 6 months to 3 years and invariably seemed to be linked to the winter months. It is unclear precisely what changes caused the increased severity seen during the second waves; one possibility is the progressive adaptation of the novel influenza virus to its new human host . Molecular analysis, for example, suggests that the 1918 Spanish influenza virus that emerged during the second wave had undergone changes in the hemagglutinin binding site that increased the binding specificity for human receptors. This is thought to have increased the replicative capacity and hence, the pathogenicity of the virus. It is also evident that as the H1N1 2009 pandemic virus continues to spread, opportunities for adaptation that increases virulence will also increase. Nonetheless, the changes needed for such adaptation and for increased virulence are unpredictable and by no means inevitable
Currently MedImmune manufactures cold-adapted (ca) live, attenuated influenza vaccine (LAIV) from specific-pathogen free (SPF) chicken eggs. Difficulties in production scale-up and potential exposure of chicken flocks to avian influenza viruses especially in the event of a pandemic influenza outbreak have prompted evaluation and development of alternative non-egg based influenza vaccine manufacturing technologies. As part of MedImmune's effort to develop the live attenuated influenza vaccine (LAIV) using cell culture production technologies we have investigated the use of high yielding, cloned MDCK cells as a substrate for vaccine production by assessing host range and virus replication of influenza virus produced from both SPF egg and MDCK cell production technologies. In addition to cloned MDCK cells the indicator cell lines used to evaluate the impact of producing LAIV in cells on host range and replication included two human cell lines: human lung carcinoma (A549) cells and human muco-epidermoid bronchiolar carcinoma (NCI H292) cells. The influenza viruses used to infect the indicators cell lines represented both the egg and cell culture manufacturing processes and included virus strains that composed the 2006-2007 influenza seasonal trivalent vaccine (A/New Caledonia/20/99 (H1N1), A/Wisconsin/67/05 (H3N2) and B/Malaysia/2506/04). Results from this study demonstrate remarkable similarity between influenza viruses representing the current commercial egg produced and developmental MDCK cell produced vaccine production platforms. MedImmune's high yielding cloned MDCK cells used for the cell culture based vaccine production were highly permissive to both egg and cell produced ca attenuated influenza viruses. Both the A549 and NCI H292 cells regardless of production system were less permissive to influenza A and B viruses than the MDCK cells. Irrespective of the indicator cell line used the replication properties were similar between egg and the cell produced influenza viruses. Based on these study results we conclude that the MDCK cell produced and egg produced vaccine strains are highly comparable.
Influenza vaccine provides protection against infection with matched strains, and this protection correlates with serum antibody titres. In addition to antibodies, influenza-specific CD8+ T-lymphocyte responses are important in decreasing disease severity and facilitating viral clearance. Because this response is directed at internal, relatively conserved antigens, it affords some cross-protection within a given subtype of influenza virus. With the possibility of a broader A(H1N1) Mexico outbreak in the fall of 2009, it appeared worthwhile studying the degree of cellular immune response-mediated cross-reactivity among influenza virus isolates. The composition of the 2006-2007 influenza vaccine included the A/New Caledonia/20/1999 strain (comprising a virus that has been circulating, and was included in vaccine preparations, for 6-7 years) and two strains not previously included (Wisconsin and Malaysia). This combination afforded us the opportunity to determine the degree of cross-reactive cellular immunity after exposure to new viral strains. We analysed the antibody responses and the phenotype and function of the T cell response to vaccine components. The results obtained show that antibody responses to A/New-Caledonia were already high and vaccination did not increase antibody or cytotoxic T lymphocyte responses. These data suggest that repeated exposure to the same influenza stain results in limited boosting of humoral and cellular immune responses.
In the present study, we used nucleotide and protein sequences of avian influenza virus H5N1, which were obtained in Asia and Africa, analyzed HA proteins using ClustalX1.83 and MEGA4.0, and built a genetic evolutionary tree of HA nucleotides. The analysis revealed that the receptor specificity amino acid of A/HK/213/2003, A/Turkey/65596/2006 and etc mutated into QNG, which could bind with á-2, 3 galactose and á-2, 6 galactose. A mutation might thus take place and lead to an outbreak of human infections of avian influenza virus. The mutations of HA protein amino acids from 2004 to 2009 coincided with human infections provided by the World Health Organization, indicating a "low-high-highest-high-low" pattern. We also found out that virus strains in Asia are from different origins: strains from Southeast Asia and East Asia are of the same origin, whereas those from West Asia, South Asia and Africa descend from one ancestor. The composition of the phylogenetic tree and mutations of key site amino acids in HA proteins reflected the fact that the majority of strains are regional and long term, and virus diffusions exist between China, Laos, Malaysia, Indonesia, Azerbaijan, Turkey and Iraq. We would advise that pertinent vaccines be developed and due attention be paid to the spread of viruses between neighboring countries and the dangers of virus mutation and evolution.
The H5 gene of avian influenza virus (AIV) strain A/chicken/Malaysia/5744/2004(H5N1) was cloned into pcDNA3.1 vector, and Esat-6 gene of Mycobacterium tuberculosis was fused into downstream of the H5 gene as a genetic adjuvant for DNA vaccine candidates. The antibody level against AIV was measured using enzyme-linked immunosorbent assay (ELISA) and haemagglutination inhibition (HI) test. Sera obtained from specific-pathogen-free chickens immunized with pcDNA3.1/H5 and pcDNA3.1/H5/Esat-6 demonstrated antibody responses as early as 2 weeks after the first immunization. Furthermore, the overall HI antibody titer in chickens immunized with pcDNA3.1/H5/Esat-6 was higher compared to the chickens immunized with pcDNA3.1/H5 (p<0.05). The results suggested that Esat-6 gene of M. tuberculosis is a potential genetic adjuvant for the development of effective H5 DNA vaccine in chickens.
A series of plasmids containing the HSP70 gene of Mycobacterium tuberculosis fused to the hemagglutinin (H5) gene of H5N1 avian influenza virus (AIV) (H5-HSP70 (heat shock protein 70) vaccine) or individual H5 gene (H5 vaccine) or HSP70 gene (HSP70 vaccine) were constructed based on the plasmid pcDNA3.1. Expression of H5 gene in Vero cells in vitro and in chickens in vivo was confirmed following their transfection and immunization with H5 or H5-HSP70 vaccines. Controls consisted of HSP70 vaccine, empty plasmid pcDNA3.1 and co-administered H5 and HSP70 vaccines. H5-HSP70 vaccine produced in chicken higher hemagglutination inhibition (HI) antibody titer than H5 vaccine. However, the increase was not statistically significant. We have demonstrated for the first time that the H5 DNA vaccine with fused HSP70 gene may produce an enhanced induction of humoral immune response to AIV in chickens.
BACKGROUND: Assessment of general public's knowledge and attitudes toward the development and prevention of new disease outbreaks is imperative because they have profound effects on health behaviors and may contribute to the control of the epidemic.
PURPOSE: To investigate the level of knowledge and attitudes towards the influenza A(H1N1) outbreak across various ethnic groups and socio-demographic backgrounds in Malaysia.
METHOD: A cross-sectional, population-based, computer-assisted telephone interview exploring knowledge and attitudes regarding influenza A(H1N1) was conducted in Malaysia. Between July 11 and September 12, 2009, a total of 1,050 respondents were interviewed (response rate 69.3%).
RESULTS: The mean total knowledge score for the overall sample was 7.30 (SD ± 1.961) out of a possible score of 13 (Chinese had the highest scores, followed by Indians, then Malays). Some erroneous beliefs about the modes of transmission were identified. The majority of the participants (73.8%) perceived the A(H1N1) infection as often deadly. Despite the overestimation of the severity of A(H1N1) infection, high confidence in preventing infection and low perceived susceptibility of infection were reported. Influenza A(H1N1)-related stigma was prevalent and exhibited differences across ethnic groups.
CONCLUSIONS: Findings suggest that provision of education and clear information are essential to correct the misconceptions, and increase perceived susceptibility to infection so that the general public will take precautions against A(H1N1) infection.
Data on the immunogenicity of the influenza vaccine in children after liver transplantation are sparse. Our study aims to evaluate the response of such patients to the trivalent influenza vaccine, administered by different protocols in 2 influenza seasons.
DNA formulations provide the basis for safe and cost effective vaccine. Low efficiency is often observed in the delivery of DNA vaccines. In order to assess a new strategy for oral DNA vaccine formulation and delivery, plasmid encoding hemagglutinin (HA) gene of avian influenza virus, A/Ck/Malaysia/5858/04 (H5N1) (pcDNA3.1/H5) was formulated using green synthesis of sliver nanoparticles (AgNP) with polyethylene glycol (PEG). AgNP were successfully synthesized uniformly dispersed with size in the range of 4 to 18 nm with an average size of 11 nm. Cytotoxicity of the prepared AgNP was investigated in vitro and in vivo using MCF-7 cells and cytokine expression, respectively. At the concentration of -5 log₁₀AgNP, no cytotoxic effects were detected in MCF-7 cells with 9.5% cell death compared to the control. One-day-old specific pathogen-free (SPF) chicks immunized once by oral gavage with 10 μl of pcDNA3.1/H5 (200 ng/ml) nanoencapsulated with 40 μl AgNP (3.7×10⁻² μg of Ag) showed no clinical manifestations. PCR successfully detect the AgNP/H5 plasmid from the duodenum of the inoculated chicken as early as 1h post-immunization. Immunization of chickens with AgNP/H5 enhanced both pro inflammatory and Th1-like expressions, although no significant differences were recorded in the chickens inoculated with AgNP, AgNP/pcDNA3.1 and the control. In addition, serum samples collected from immunized chickens with AgNP/H5 showed rapidly increasing antibody against H5 on day 14 after immunization. The highest average antibody titres were detected on day 35 post-immunization at 51.2±7.5. AgNP/H5 also elicited both CD4+ and CD8+ T cells in the immunized chickens as early as day 14 after immunization, at 7.5±2.0 and 20±1.9 percentage, respectively. Hence, single oral administrations of AgNP/H5 led to induce both the antibody and cell-mediated immune responses as well as enhanced cytokine production.