Influenza vaccine induced antibody responses in relation to evolution of influenza A viruses

Influenza A viruses (IAVs) cause yearly epidemics and occasionally appearing new pandemics. IAVs are subtyped based on their virion surface glycoproteins haemagglutinin and neuraminidase. Seasonal IA epidemics in humans are currently caused by A(H1N1) and A(H3N2) viruses with varying incidence. The natural reservoir of IAVs is birds, and the virus also infects swine and other mammalian species. Global monitoring of the genetic drift and antigenic characteristics of influenza viruses is needed for vaccine strain selection and pandemic preparedness. Vaccine-induced humoral immunity can be analyzed by measuring serum antibodies. In this study, serum antibody levels in adults were assessed before and after vaccination with different seasonal influenza vaccines and pre-pandemic A(H5N1) vaccine candidate viruses. Traditional haemagglutination inhibition (HI) assay was used to measure antibody levels. In addition, a colorimetric microneutralization test (MNT) was optimized to measure functional neutralizing antibodies. The correlation between the methods was found to be high. One of the most effective ways to prevent an infectious disease is vaccination, if circulating viruses are well-matched with vaccine viruses. The protective efficacy of influenza vaccines varies mainly due to virus evolution. In this study we reported reduced cross-protection against drifted A(H3N2) viruses. The latest influenza pandemic was caused by a novel A(H1N1)pdm09 virus, since pre-existing immunity in the majority of human population was missing. After the pandemic, the A(H1N1)pdm09 viruses have continued to circulate as epidemic strains. In this study, seasonal influenza vaccines were found to induce high levels of cross-reactive antibody responses against different genetic group A(H1N1)pdm09 viruses for several years after the pandemic. Avian influenza viruses usually do not easily transmit to humans. However, A(H5N1) viruses have caused serious disease and considerable mortality, which have led to the development of various avian influenza vaccine candidates. Prepandemic A(H5N1) stockpile vaccine was also purchased in Finland. In this study we demonstrated that two heterologous A(H5N1) vaccinations induced longlasting cross-clade humoral immunity.Influenssarokotteiden aikaansaamat vasta-ainevasteet suhteessa influenssa A -virusten muuntumiseen Tarttuvuutensa ja muuntautumiskykynsä vuoksi influenssa A -virukset aiheuttavat vuosittaisia epidemioita ja ajoittain myös maailmanlaajuisia pandemioita. Influenssa A -virukset luokitellaan useisiin alatyyppeihin viruksen kahta eri pintaproteiinia määrittävien hemagglutiniini- ja neuraminidaasigeenien perusteella. A(H1N1)- ja A(H3N2)-alatyypin virukset aiheuttavat vuosittain epidemioita vaihtelevin valtasuhtein. Influenssa A -viruksia esiintyy erityisesti linnuissa, mutta myös sioissa ja joissain muissa nisäkäslajeissa. Influenssavirusten evoluution maailmanlaajuinen seuranta tukee rokotevirusten valintaa ja pandemioihin varautumista. Rokotteen laukaiseman vasta-ainevälitteisen immuniteetin muodostumista voidaan arvioida mittaamalla virusvasta-aineita. Tässä tutkimuksessa tarkasteltiin eri kausi-influenssarokotteiden sekä prepandeemisten A(H5N1)- lintu-influenssarokotteiden synnyttämiä vasta-ainetasoja aikuisilla. Tutkimusmenetelmänä käytettiin perinteistä hemagglutinaation inhibitio -testiä, jonka rinnalle optimoitiin kolorimetrinen mikroneutralisaatiotesti. Menetelmien välinen korrelaatio oli erittäin hyvä. Rokottaminen suojaa tehokkaimmin influenssaa vastaan silloin, kun kiertävät virukset ovat samankaltaisia ennakoidun rokoteviruksen kanssa. Kausi-influenssarokotteiden suojateho vaihtelee virusten evoluutiosta johtuen kaudesta toiseen. Tässä tutkimuksessa tunnistettiin alentunut immuunivaste muuntuneita A(H3N2)-viruksia kohtaan. Viimeisimmän influenssapandemian aiheutti A(H1N1)pdm09-virus, jota vastaan valtaväestöllä ei ollut aiempaa immuniteettia. Pandemian aiheuttaneen viruksen jälkeläisvirukset jäivät kiertämään väestössä normaalina kausi-influenssana. Tässä tutkimuksessa osoitettiin, että kausi-influenssarokotteet saivat aikaan hyvän immuunisuojan eri jälkeläisviruskantoja vastaan useita vuosia pandemian jälkeen. Lintuinfluenssavirukset tarttuvat ihmiseen yleensä huonosti. Vakavampia taudinkuvia ja huomattavaa kuolleisuutta aiheuttaneet A(H5N1)-tartunnat ovat aiheuttaneet huolta uudesta pandemiasta, mistä syystä on kehitetty erilaisia lintuinfluenssarokotekantoja. Prepandeeminen H5N1-mallirokote varattiin myös Suomeen. Tässä tutkimuksessa todettiin, että kahdella, eri viruskantoja sisältävällä H5N1-rokotteella saatiin aikaan laajakirjoinen vasta-ainevälitteinen immuniteetti

Seasonal influenza vaccines induced high levels of neutralizing cross-reactive antibody responses against different genetic group influenza A(H1N1)pdm09 viruses

Influenza A(H1N1)pdm09 viruses have been circulating throughout the world since the 2009 pandemic. A/California/07/2009 (H1N1) virus was included in seasonal influenza vaccines for seven years altogether, providing a great opportunity to analyse vaccine-induced immunity in relation to the postpandemic evolution of the A(H1N1)pdm09 virus. Serum antibodies against various epidemic strains of influenza A (H1N1)pdm09 viruses were measured among health care workers (HCWs) by haemagglutination inhibition and microneutralization tests before and after 2010 and 2012 seasonal influenza vaccinations. We detected high responses of vaccine-induced neutralizing antibodies to six distinct genetic groups. Our results indicate antigenic similarity between vaccine and circulating A(H1N1)pdm09 strains, and substantial vaccine-induced immunity against circulating epidemic viruses. (C) 2019 Published by Elsevier Ltd.Peer reviewe

Long-lasting heterologous antibody responses after sequential vaccination with A/Indonesia/5/2005 and A/Vietnam/1203/2004 pre-pandemic influenza A(H5N1) virus vaccines

Background: Avian influenza A(H5N1) viruses have caused sporadic infections in humans and thus they pose a significant global health threat. Among symptomatic patients the case fatality rate has been ca. 50%. H5N1 viruses exist in multiple clades and subclades and several candidate vaccines have been developed to prevent A(H5N1) infection as a principal measure for preventing the disease.Methods: Serum antibodies against various influenza A(H5N1) Glade viruses were measured in adults by ELISA-based microneutralization and haemagglutination inhibition tests before and after vaccination with two different A(H5N1) vaccines in 2009 and 2011.Results: Two doses of AS03-adjuvanted A/Indonesia/5/2005 vaccine induced good homologous but poor heterologous neutralizing antibody responses against different Glade viruses. However, non-adjuvanted A/Vietnam/1203/2004 booster vaccination in 2011 induced very strong and long-lasting homologous and heterologous antibody responses while homologous response remained weak in naive subjects.Conclusions: Sequential vaccination with two different A(H5N1) pre-pandemic vaccines induced long-lasting high level cross-Glade immunity against influenza A(H5N1) strains, thus supporting a prime-boost vaccination strategy in pandemic preparedness plans. </div

A Highly Sensitive and Specific SARS-CoV-2 Spike- and Nucleoprotein-Based Fluorescent Multiplex Immunoassay (FMIA) to Measure IgG, IgA, and IgM Class Antibodies

Validation and standardization of accurate serological assays are crucial for the surveillance of the coronavirus disease 2019 (COVID-19) pandemic and population immunity. We describe the analytical and clinical performance of an in-house fluorescent multiplex immunoassay (FMIA) for simultaneous quantification of antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein and spike glycoprotein. Furthermore, we calibrated IgG-FMIA against World Health Organization (WHO) International Standard and compared FMIA results to an in-house enzyme immunoassay (EIA) and a microneutralization test (MNT). We also compared the MNT results of two laboratories. IgG-FMIA displayed 100% specificity and sensitivity for samples collected 13 to 150 days post-onset of symptoms (DPO). For IgA- and IgM-FMIA, 100% specificity and sensitivity were obtained for a shorter time window (13 to 36 and 13 to 28 DPO for IgA- and IgM-FMIA, respectively). FMIA and EIA results displayed moderate to strong correlation, but FMIA was overall more specific and sensitive. IgG-FMIA identified 100% of samples with neutralizing antibodies (NAbs). Anti-spike IgG concentrations correlated strongly (r = 0.77 to 0.84, P < 2.2 x 10(-16)) with NAb titers, and the two laboratories' NAb titers displayed a very strong correlation (r = 0.95, P< 2.2 x 10(-16)). Our results indicate good correlation and concordance of antibody concentrations measured with different types of in-house SARS-CoV-2 antibody assays. Calibration against the WHO international standard did not, however, improve the comparability of FMIA and EIA results. IMPORTANCE SARS-CoV-2 serological assays with excellent clinical performance are essential for reliable estimation of the persistence of immunity after infection or vaccination. In this paper we present a thoroughly validated SARS-CoV-2 serological assay with excellent clinical performance and good comparability to neutralizing antibody titers. Neutralization tests are still considered the gold standard for SARS-CoV-2 serological assays, but our assay can identify samples with neutralizing antibodies with 100% sensitivity and 96% specificity without the need for laborious and slow biosafety level 3 (BSL-3) facility-requiring analyses.Peer reviewe

Clinical validation of automated and rapid mariPOC SARS-CoV-2 antigen test

Publisher Copyright: © 2021, The Author(s).COVID-19 diagnostics was quickly ramped up worldwide early 2020 based on the detection of viral RNA. However, based on the scientific knowledge for pre-existing coronaviruses, it was expected that the SARS-CoV-2 RNA will be detected from symptomatic and at significant rates also from asymptomatic individuals due to persistence of non-infectious RNA. To increase the efficacy of diagnostics, surveillance, screening and pandemic control, rapid methods, such as antigen tests, are needed for decentralized testing and to assess infectiousness. A novel automated mariPOC SARS-CoV-2 test was developed for the detection of conserved structural viral nucleocapsid proteins. The test utilizes sophisticated optical laser technology for two-photon excitation and individual detection of immunoassay solid-phase particles. We validated the new method against qRT-PCR. Sensitivity of the test was 100.0% (13/13) directly from nasopharyngeal swab specimens and 84.4% (38/45) from swab specimens in undefined transport mediums. Specificity of the test was 100.0% (201/201). The test's limit of detection was 2.7 TCID50/test. It showed no cross-reactions. Our study shows that the new test can detect infectious individuals already in 20 min with clinical sensitivity close to qRT-PCR. The mariPOC is a versatile platform for syndromic testing and for high capacity infection control screening of infectious individuals.Peer reviewe

Sinun influenssarokotuksesi on osa potilasturvallisuutta

Terveydenhuollon henkilöstön vuosittaiset influenssarokotukset ovat olennainen osa vakavasti perussairaiden henkilöiden epäsuoraa suojaamista influenssainfektiota vastaan. Erityisesti lääketieteellisiin riskiryhmiin kuuluvilla influenssainfektio voi johtaa vakavaan sairaala- tai jopa tehohoitoa vaativaan tautiin

Comparison of the clinical characteristics and outcomes of hospitalized adult COVID-19 and influenza patients - a prospective observational study

Background We compared the clinical characteristics, findings, and outcomes of hospitalized patients with coronavirus disease 2019 (COVID-19) or influenza to detect relevant differences. Methods From December 2019 to April 2020, we recruited all eligible hospitalized adults with respiratory infection to a prospective observational study at a tertiary care hospital in Finland. Influenza and SARS-CoV-2 infections were confirmed by RT-PCR. Follow-up lasted for 3 months from admission. Results We included 61 patients, of whom 28 were COVID-19 and 33 influenza patients with median ages of 53 and 56 years. Majority of both COVID-19 and influenza patients were men (61% vs. 67%) and had at least one comorbidity (68% vs. 85%). Pulmonary diseases and current smoking were less common among COVID-19 than influenza patients (5 [18%] vs. 15 [45%], p=.03 and 1 [4%] vs. 10 [30%], p=.008). In chest X-ray at admission, ground-glass opacities (GGOs) and consolidations were more frequent among COVID-19 than influenza patients (19 [68%] and 7 [21%], p.001). Severe disease and intensive care unit (ICU) admission occurred more often among COVID-19 than influenza patients (26 [93%] vs. 19 [58%], p=.003 and 8 [29%] vs. 2 [6%], p=.034). COVID-19 patients were hospitalized longer than influenza patients (six days [IQR 4-21] vs. 3 [2-4], p.001). Conclusions Bilateral GGOs and consolidations in chest X-ray may help to differentiate COVID-19 from influenza. Hospitalized COVID-19 patients had more severe disease, required longer hospitalization and were admitted to ICU more often than influenza patients, which has important implications for public health policies.Peer reviewe

Vaccine-Induced Antibody Responses against SARS-CoV-2 Variants-Of-Concern Six Months after the BNT162b2 COVID-19 mRNA Vaccination

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has raised concern about increased transmissibility, infectivity, and immune evasion from a vaccine and infection-induced immune responses. Although COVID-19 mRNA vaccines have proven to be highly effective against severe COVID-19 disease, the decrease in vaccine efficacy against emerged Beta and Delta variants emphasizes the need for constant monitoring of new virus lineages and studies on the persistence of vaccine-induced neutralizing antibodies. To analyze the dynamics of COVID-19 mRNA vaccine-induced antibody responses, we followed 52 health care workers in Finland for 6 months after receiving two doses of BNT162b2 vaccine with a 3-week interval. We demonstrate that, although anti-S1 antibody levels decrease 2.3-fold compared to peak antibody levels, anti-SARS-CoV-2 antibodies persist for months after BNT162b2 vaccination. Variants D614G, Alpha, and Eta are neutralized by sera of 100% of vaccinees, whereas neutralization of Delta is 3.8-fold reduced and neutralization of Beta is 5.8-fold reduced compared to D614G. Despite this reduction, 85% of sera collected 6 months postvaccination neutralizes Delta variant. IMPORTANCE A decrease in vaccine efficacy against emerging SARS-CoV-2 variants has increased the importance of assessing the persistence of SARS-CoV-2 spike proteinspecific antibodies and neutralizing antibodies. Our data show that after 6 months post two doses of BNT162b2 vaccine, antibody levels decrease yet remain detectable and capable of neutralizing emerging variants. By monitoring the vaccine-induced antibody responses, vaccination strategies and administration of booster doses can be optimized.Peer reviewe