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Clinical differences between influenza A (H1N1) pdm09 & influenza B infections identified through active community surveillance in North India.

ABSTRACT: Most studies on the clinical presentation with influenza viruses have been conducted in outpatient or inpatient medical facilities with only a few studies in community settings. Clinical differences between influenza A (H1N1) pdm 09 and influenza B virus infections have importance for community-based public health surveillance. An active community surveillance at the time of emergence of pandemic influenza provided us with an opportunity to compare the clinical features among patients infected with influenza A (H1N1) pdm09 virus and those with influenza B virus co-circulating in an active community-based weekly surveillance in three villages in Faridabad, Haryana, north India.Active surveillance for febrile acute respiratory infection (FARI) was carried out in a rural community (n=16,182) in the context of an inactivated trivalent influenza vaccine trial (among children <11 yr). Individuals with FARI were assessed clinically by nurses and respiratory samples collected and tested for influenza viruses by real time RT-PCR from November 2009 to August 2010. Clinical symptoms of patients with influenza A (H1N1) pdm 09 and influenza B infection were compared.Of the 4796 samples tested, 822 (17%) were positive for influenza virus. Of these, 443 (54%) were influenza A (H1N1) pdm09, 373 (45%) were influenza B and six were other subtypes/mixed infections. The mean age was lower for patients with influenza B (16.4 yr) than influenza A (H1N1) pdm09 infection (18.7 yr; P=0.04). Among children aged 5-18 yr, chills/rigours (OR 4.0; CI 2.2, 7.4), sore throat (OR 6.8; CI 2.3, 27.3) and headache (OR2.0; CI 1.3, 3.3) were more common in influenza A (H1N1) pdm09 infection than in influenza B cases. Chills/rigours (OR 2.4; CI 1.4, 4.0) and headache (OR 1.7; CI 1.0, 2.7) were associated with influenza A (H1N1) pdm09 infection in those >18 yr. No significant differences were seen in children <5 yr.Our findings show that the differences in the clinical presentation of influenza A(H1N1)pdm09 and influenza B infections are not likely to be of clinical or public health significance.

SUBMITTER: Purakayastha DR

PROVIDER: S-EPMC3978989 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Clinical differences between influenza A (H1N1) pdm09 & influenza B infections identified through active community surveillance in North India.

Purakayastha Debjani Ram DR Gupta Vivek V Broor Shobha S Sullender Wayne W Fowler Karen K Widdowson Marc-Alain MA Lal Renu B RB Krishnan Anand A

The Indian journal of medical research 20131201 6

<h4>Background & objectives</h4>Most studies on the clinical presentation with influenza viruses have been conducted in outpatient or inpatient medical facilities with only a few studies in community settings. Clinical differences between influenza A (H1N1) pdm 09 and influenza B virus infections have importance for community-based public health surveillance. An active community surveillance at the time of emergence of pandemic influenza provided us with an opportunity to compare the clinical fe ...[more]

PMID: 24521643

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Project description:ObjectivesTo review neurological complications after the influenza A (H1N1) pdm09, highlighting the clinical differences between patients with post-vaccine or viral infection.DesignA search on Medline, Ovid, EMBASE, and PubMed databases using the keywords “neurological complications of Influenza AH1N1” or “post-vaccine Influenza AH1N1.”SettingOnly papers written in English, Spanish, German, French, Portuguese, and Italian published from March 2009 to December 2012 were included.SampleWe included 104 articles presenting a total of 1636 patient cases. In addition, two cases of influenza vaccine-related neurological events from our neurological care center, arising during the period of study, were also included.Main outcome measuresDemographic data and clinical diagnosis of neurological complications and outcomes: death, neurological sequelae or recovery after influenza A (H1N1) pdm09 vaccine or infection.ResultsThe retrieved cases were divided into two groups: the postvaccination group, with 287 patients, and the viral infection group, with 1349 patients. Most patients in the first group were adults. The main neurological complications were Guillain-Barre syndrome (GBS) or polyneuropathy (125), and seizures (23). All patients survived. Pediatric patients were predominant in the viral infection group. In this group, 60 patients (4.7%) died and 52 (30.1%) developed permanent sequelae. A wide spectrum of neurological complications was observed.ConclusionsFatal cases and severe, permanent, neurological sequelae were observed in the infection group only. Clinical outcome was more favorable in the post-vaccination group. In this context, the relevance of an accurate neurological evaluation is demonstrated for all suspicious cases, as well as the need of an appropriate long-term clinical and imaging follow-up of infection and post-vaccination events related to influenza A (H1N1) pdm09, to clearly estimate the magnitude of neurological complications leading to permanent disability.

Project description:Immune imprinting is a driver known to shape the anti-hemagglutinin (HA) antibody landscape of individuals born within the same birth cohort. With the HA and neuraminidase (NA) proteins evolving at different rates under immune selection pressures, anti-HA and anti-NA antibody responses since childhood influenza virus infections have not been evaluated in parallel at the individual level. This is partly due to the limited knowledge of changes in NA antigenicity, as seasonal influenza vaccines have focused on generating neutralizing anti-HA antibodies against HA antigenic variants. Here, we systematically characterized the NA antigenic variants of seasonal A(H1N1) viruses from 1977 to 1991 and completed the antigenic profile of N1 NAs from 1977 to 2015. We identified that NA proteins of A/USSR/90/77, A/Singapore/06/86, and A/Texas/36/91 were antigenically distinct and mapped N386K as a key determinant of the NA antigenic change from A/USSR/90/77 to A/Singapore/06/86. With comprehensive panels of HA and NA antigenic variants of A(H1N1) and A(H1N1)pdm09 viruses, we determined hemagglutinin inhibition (HI) and neuraminidase inhibition (NI) antibodies from 130 subjects born between 1950 and 2015. Age-dependent imprinting was observed for both anti-HA and anti-NA antibodies, with the peak HI and NI titers predominantly detected from subjects at 4 to 12 years old during the year of initial virus isolation, except the age-independent anti-HA antibody response against A(H1N1)pdm09 viruses. More participants possessed antibodies that reacted to multiple antigenically distinct NA proteins than those with antibodies that reacted to multiple antigenically distinct HA proteins. Our results support the need to include NA proteins in seasonal influenza vaccine preparations. IMPORTANCE Seasonal influenza vaccines have aimed to generate neutralizing anti-HA antibodies for protection since licensure. More recently, anti-NA antibodies have been established as an additional correlate of protection. While HA and NA antigenic changes occurred discordantly, the anti-HA and anti-NA antibody profiles have rarely been analyzed in parallel at the individual level, due to the limited knowledge on NA antigenic changes. By characterizing NA antigenic changes of A(H1N1) viruses, we determined the anti-HA and anti-NA antibody landscape against antigenically distinct A(H1N1) and A(H1N1)pdm09 viruses using sera of 130 subjects born between 1950 and 2015. We observed age-dependent imprinting of both anti-HA and anti-NA antibodies against strains circulated during the first decade of life. A total of 67.7% (88/130) and 90% (117/130) of participants developed cross-reactive antibodies to multiple HA and NA antigens at titers ≥1:40. With slower NA antigenic changes and cross-reactive anti-NA antibody responses, including NA protein in influenza vaccine preparation may enhance vaccine efficacy.

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Clinical differences between influenza A (H1N1) pdm09 & influenza B infections identified through active community surveillance in North India.

Publications

Clinical differences between influenza A (H1N1) pdm09 & influenza B infections identified through active community surveillance in North India.

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