Avian Influenza outbreaks: Human infection risks for beach users - One health concern and environmental surveillance implications.

Despite its popularity for water activities, such as swimming, surfing, fishing, and rafting, inland and coastal bathing areas occasionally experience outbreaks of highly pathogenic avian influenza virus (HPAI), including A(H5N1) clade 2.3.4.4b. Asymptomatic infections and symptomatic outbreaks often impact many aquatic birds, which increase chances of spill-over events to mammals and pose concerns for public health. This review examined the existing literature to assess avian influenza virus (AIV) transmission risks to beachgoers and the general population. A comprehensive understanding of factors governing such crossing of the AIV host range is currently lacking. There is limited knowledge on key factors affecting risk, such as species-specific interactions with host cells (including binding, entry, and replication via viral proteins hemagglutinin, neuraminidase, nucleoprotein, and polymerase basic protein 2), overcoming host restrictions, and innate immune response. AIV efficiently transmits between birds and to some extent between marine scavenger mammals in aquatic environments via consumption of infected birds. However, the current literature lacks evidence of zoonotic AIV transmission via contact with the aquatic environment or consumption of contaminated water. The zoonotic transmission risk of the circulating A(H5N1) clade 2.3.4.4b virus to the general population and beachgoers is currently low. Nevertheless, it is recommended to avoid direct contact with sick or dead birds and to refrain from bathing in locations where mass bird mortalities are reported. Increasing reports of AIVs spilling over to non-human mammals have raised valid concerns about possible virus mutations that lead to crossing the species barrier and subsequent risk of human infections and outbreaks.

Highly pathogenic avian influenza A(H5N1) virus infections on fur farms connected to mass mortalities of black-headed gulls, Finland, July to October 2023.

Highly pathogenic avian influenza (HPAI) has caused widespread mortality in both wild and domestic birds in Europe 2020-2023. In July 2023, HPAI A(H5N1) was detected on 27 fur farms in Finland. In total, infections in silver and blue foxes, American minks and raccoon dogs were confirmed by RT-PCR. The pathological findings in the animals include widespread inflammatory lesions in the lungs, brain and liver, indicating efficient systemic dissemination of the virus. Phylogenetic analysis of Finnish A(H5N1) strains from fur animals and wild birds has identified three clusters (Finland I-III), and molecular analyses revealed emergence of mutations known to facilitate viral adaptation to mammals in the PB2 and NA proteins. Findings of avian influenza in fur animals were spatially and temporally connected with mass mortalities in wild birds. The mechanisms of virus transmission within and between farms have not been conclusively identified, but several different routes relating to limited biosecurity on the farms are implicated. The outbreak was managed in close collaboration between animal and human health authorities to mitigate and monitor the impact for both animal and human health.

Highly pathogenic avian influenza A(H5N1) virus infection in foxes with PB2-M535I identified as a novel mammalian adaptation, Northern Ireland, July 2023.

We report cases of mammalian infection with highly pathogenic avian influenza (HPAI) virus A(H5N1) clade 2.3.4.4b in Northern Ireland. Two common gulls (Larus canus) and two red fox kits (Vulpes vulpes), were found dead in close vicinity. Comparison of viral whole genome sequences obtained from the animals identified a novel mammalian adaptation, PB2-M535I. Analysis of genetic sequences from other recent mammalian infections shows that this mutation has arisen on at least five occasions in three European countries since April 2023.

Highly pathogenic avian influenza A(H5N1) virus infection on multiple fur farms in the South and Central Ostrobothnia regions of Finland, July 2023.

Since mid-July 2023, an outbreak caused by highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b genotype BB is ongoing among farmed animals in South and Central Ostrobothnia, Finland. Infections in foxes, American minks and raccoon dogs have been confirmed on 20 farms. Genetic analysis suggests introductions from wild birds scavenging for food in farm areas. Investigations point to direct transmission between animals. While no human infections have been detected, control measures are being implemented to limit spread and human exposure.

High secondary attack rate and persistence of SARS-CoV-2 antibodies in household transmission study participants, Finland 2020-2021.

Background: Household transmission studies offer the opportunity to assess both secondary attack rate (SAR) and persistence of SARS-CoV-2 antibodies over time. Methods: In Spring 2020, we invited confirmed COVID-19 cases and their household members to four visits, where we collected nasopharyngeal and serum samples over 28 days after index case onset. We calculated SAR based on the presence of SARS-CoV-2 neutralizing antibodies (NAb) and assessed the persistence of NAb and IgG antibodies (Ab) against SARS-CoV-2 spike glycoprotein and nucleoprotein. Results: SAR was 45% (39/87), including 35 symptomatic secondary cases. During the initial 28-day follow-up, 62% (80/129) of participants developed NAb. Of those that seroconverted, 90% (63/70), 85% (63/74), and 78% (45/58) still had NAb to early B-lineage SARS-CoV-2 3, 6, and 12 months after the onset of the index case. Anti-spike IgG Ab persisted in 100% (69/69), 97% (72/74), and 93% (55/59) of seroconverted participants after 3, 6, and 12 months, while anti-nucleoprotein IgG Ab levels waned faster, persisting in 99% (68/69), 78% (58/74), and 55% (39/71) of participants, respectively. Conclusion: Following detection of a COVID-19 case in a household, other members had a high risk of becoming infected. NAb to early B-lineage SARS-CoV-2 persisted for at least a year in most cases.

Genomic and epidemiological report of the recombinant XJ lineage SARS-CoV-2 variant, detected in northern Finland, January 2022.

Recombinant sequences of the SARS-CoV-2 Omicron variant were detected in surveillance samples collected in north-western Finland in January 2022. We detected 191 samples with an identical genome arrangement in weeks 3 to 11, indicating sustained community transmission. The recombinant lineage has a 5'-end of BA.1, a recombination breakpoint between orf1a and orf1b (nucleotide position 13,296-15,240) and a 3'-end of BA.2 including the S gene. We describe the available genomic and epidemiological data about this currently circulating recombinant XJ lineage.

Introduction and Rapid Spread of SARS-CoV-2 Omicron Variant and Dynamics of BA.1 and BA.1.1 Sublineages, Finland, December 2021.

Multiple introductions of SARS-COV-2 Omicron variant BA.1 and BA.1.1. lineages to Finland were detected in early December 2021. Within 3 weeks, Omicron overtook Delta as the most common variant in the capital region. Sequence analysis demonstrated the emergence and spread through community transmission of a large cluster of BA.1.1 virus.

Re-emergence of enterovirus D68 in Europe after easing the COVID-19 lockdown, September 2021.

We report a rapid increase in enterovirus D68 (EV-D68) infections, with 139 cases reported from eight European countries between 31 July and 14 October 2021. This upsurge is in line with the seasonality of EV-D68 and was presumably stimulated by the widespread reopening after COVID-19 lockdown. Most cases were identified in September, but more are to be expected in the coming months. Reinforcement of clinical awareness, diagnostic capacities and surveillance of EV-D68 is urgently needed in Europe.

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

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.

Incidence Trends for SARS-CoV-2 Alpha and Beta Variants, Finland, Spring 2021.

Severe acute respiratory syndrome coronavirus 2 Alpha and Beta variants became dominant in Finland in spring 2021 but had diminished by summer. We used phylogenetic clustering to identify sources of spreading. We found that outbreaks were mostly seeded by a few introductions, highlighting the importance of surveillance and prevention policies.

Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens.

The gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosis is reverse transcription (RT)-PCR from a nasopharyngeal swab specimen (NPS). Its collection involves close contact between patients and health care workers, requiring a significant amount of workforce and putting them at risk of infection. We evaluated self-collection of alternative specimens and compared their sensitivity and cycle threshold (CT) values to those of NPS. We visited acute coronavirus disease 2019 (COVID-19) outpatients to collect concomitant NPS and gargle specimens and had patients self-collect gargle and either sputum or spit specimens the next morning. We included 40 patients and collected 40 concomitant NPS and gargle specimens, as well as 40 gargle, 22 spit, and 16 sputum specimens the next day (2 patients could not produce sputum). All specimens were as sensitive as NPS. Gargle specimens had a sensitivity of 0.97 (95% confidence interval [CI], 0.92 to 1.00), whether collected concomitantly with NPS or the next morning. Next-morning spit and sputum specimens showed sensitivities of 1.00 (95% CI, 1.00 to 1.00) and 0.94 (95% CI, 0.87 to 1.00]), respectively. The gargle specimens had significantly higher mean CT values of 29.89 (standard deviation [SD], 4.63; P < 0.001) and 29.25 (SD, 3.99; P < 0.001) when collected concomitantly and the next morning, respectively, compared to NPS (22.07 [SD, 4.63]). CT values obtained with spit (23.51 [SD, 4.57]; P = 0.11) and sputum (25.82 [SD, 9.21]; P = 0.28) specimens were close to those of NPS. All alternative specimen collection methods were as sensitive as NPS, but spit collection appeared more promising, with a low CT value and ease of collection. Our findings warrant further investigation. IMPORTANCE Control of the COVID-19 pandemic relies heavily on a test-trace-isolate strategy. The most commonly used specimen for diagnosis of SARS-CoV-2 infection is a nasopharyngeal swab. However, this method is quite uncomfortable for the patient, requires specific equipment (nose swabs and containers), and requires close proximity to health care workers, putting them at risk of infection. Developing alternative sampling strategies could decrease the burden for health care workers, help overcome potential shortages of equipment, and improve acceptability of testing by reducing patient discomfort.

An outbreak caused by the SARS-CoV-2 Delta variant (B.1.617.2) in a secondary care hospital in Finland, May 2021.

An outbreak caused by the SARS-CoV-2 Delta variant (B.1.617.2) spread from one inpatient in a secondary care hospital to three primary care facilities, resulting in 58 infections including 18 deaths in patients and 45 infections in healthcare workers (HCW). Only one of the deceased cases was fully vaccinated. Transmission occurred despite the use of personal protective equipment by the HCW, as advised in national guidelines, and a high two-dose COVID-19 vaccination coverage among permanent staff members in the COVID-19 cohort ward.

Characteristics of SARS-CoV-2 variants of concern B.1.1.7, B.1.351 or P.1: data from seven EU/EEA countries, weeks 38/2020 to 10/2021.

We compared 19,207 cases of SARS-CoV-2 variant B.1.1.7/S gene target failure (SGTF), 436 B.1.351 and 352 P.1 to non-variant cases reported by seven European countries. COVID-19 cases with these variants had significantly higher adjusted odds ratios for hospitalisation (B.1.1.7/SGTF: 1.7, 95% confidence interval (CI): 1.0-2.9; B.1.351: 3.6, 95% CI: 2.1-6.2; P.1: 2.6, 95% CI: 1.4-4.8) and B.1.1.7/SGTF and P.1 cases also for intensive care admission (B.1.1.7/SGTF: 2.3, 95% CI: 1.4-3.5; P.1: 2.2, 95% CI: 1.7-2.8).

Epidemiology of laboratory-confirmed influenza among kidney transplant recipients compared to the general population-A nationwide cohort study.

Seasonal influenza causes morbidity and mortality after organ transplantation. We quantified the detection of laboratory-confirmed influenza among kidney transplant recipients compared to the general population in a nationwide cohort. All laboratory-confirmed cases of influenza and hospitalizations due to influenza among all kidney transplant recipients in our country between 1995 and 2017 were captured with database linkage from statutory national registries. Data from the general population of Finland, population 5.5 million, were used for comparisons. Annual incidences of influenza and hospitalizations due to influenza, and standardized incidence ratios (SIR) were calculated. Altogether 3904 kidney transplant recipients with a total follow-up of 37 175 patient-years were included. Incidence of laboratory-confirmed influenza was 9.0 per 1000 patient years in 2003-2019, and 18.0 per 1000 patient years during 2015-2019. The risk of laboratory-confirmed influenza was significantly higher among kidney transplant recipients compared to the general population (SIR 5.1, 95% CI 4.5-5.7). SIR for hospitalization due to influenza was 4.4 (95% CI 3.4-4.7). Mortality of the hospitalized patients was 9%, and 5% of the patients with laboratory-confirmed influenza. Detection of laboratory-confirmed influenza is increased fivefold and risk of hospitalization due to influenza more than fourfold among kidney transplant recipients compared to the general population.

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) clade 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 clade 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 naïve subjects. CONCLUSIONS: Sequential vaccination with two different A(H5N1) pre-pandemic vaccines induced long-lasting high level cross-clade immunity against influenza A(H5N1) strains, thus supporting a prime-boost vaccination strategy in pandemic preparedness plans.

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.

Serological and molecular findings during SARS-CoV-2 infection: the first case study in Finland, January to February 2020.

The first case of coronavirus disease (COVID-19) in Finland was confirmed on 29 January 2020. No secondary cases were detected. We describe the clinical picture and laboratory findings 3-23 days since the first symptoms. The SARS-CoV-2/Finland/1/2020 virus strain was isolated, the genome showing a single nucleotide substitution to the reference strain from Wuhan. Neutralising antibody response appeared within 9 days along with specific IgM and IgG response, targeting particularly nucleocapsid and spike proteins.

Vaccine effectiveness against influenza A(H3N2) and B among laboratory-confirmed, hospitalised older adults, Europe, 2017-18: A season of B lineage mismatched to the trivalent vaccine.

BACKGROUND: Influenza A(H3N2), A(H1N1)pdm09 and B viruses co-circulated in Europe in 2017-18, predominated by influenza B. WHO-recommended, trivalent vaccine components were lineage-mismatched for B. The I-MOVE hospital network measured 2017-18 seasonal influenza vaccine effectiveness (IVE) against influenza A(H3N2) and B among hospitalised patients (≥65 years) in Europe. METHODS: Following the same generic protocol for test-negative design, hospital teams in nine countries swabbed patients ≥65 years with recent onset (≤7 days) severe acute respiratory infection (SARI), collecting information on demographics, vaccination status and underlying conditions. Cases were RT-PCR positive for influenza A(H3N2) or B; controls: negative for any influenza. "Vaccinated" patients had SARI onset >14 days after vaccination. We measured pooled IVE against influenza, adjusted for study site, age, sex, onset date and chronic conditions. RESULTS: We included 3483 patients: 376 influenza A(H3N2) and 928 B cases, and 2028 controls. Most (>99%) vaccinated patients received the B lineage-mismatched trivalent vaccine. IVE against influenza A(H3N2) was 24% (95% CI: 2 to 40); 35% (95% CI: 6 to 55) in 65- to 79-year-olds and 14% (95% CI: -22 to 39) in ≥80-year-olds. Against influenza B, IVE was 30% (95% CI: 16 to 41); 37% (95% CI: 19 to 51) in 65- to 79-year-olds and 19% (95% CI: -7 to 38) in ≥80-year-olds. CONCLUSIONS: IVE against influenza B was similar to A(H3N2) in hospitalised older adults, despite trivalent vaccine and circulating B lineage mismatch, suggesting some cross-protection. IVE was lower in those ≥80 than 65-79 years. We reinforce the importance of influenza vaccination in older adults as, even with a poorly matched vaccine, it still protects one in three to four of this population from severe influenza.

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.

Determinants of Fatal Outcome in Patients Admitted to Intensive Care Units With Influenza, European Union 2009-2017.

BACKGROUND: Morbidity, severity, and mortality associated with annual influenza epidemics are of public health concern. We analyzed surveillance data on hospitalized laboratory-confirmed influenza cases admitted to intensive care units to identify common determinants for fatal outcome and inform and target public health prevention strategies, including risk communication. METHODS: We performed a descriptive analysis and used Poisson regression models with robust variance to estimate the association of age, sex, virus (sub)type, and underlying medical condition with fatal outcome using European Union data from 2009 to 2017. RESULTS: Of 13 368 cases included in the basic dataset, 2806 (21%) were fatal. Age ≥40 years and infection with influenza A virus were associated with fatal outcome. Of 5886 cases with known underlying medical conditions and virus A subtype included in a more detailed analysis, 1349 (23%) were fatal. Influenza virus A(H1N1)pdm09 or A(H3N2) infection, age ≥60 years, cancer, human immunodeficiency virus infection and/or other immune deficiency, and heart, kidney, and liver disease were associated with fatal outcome; the risk of death was lower for patients with chronic lung disease and for pregnant women. CONCLUSIONS: This study re-emphasises the importance of preventing influenza in the elderly and tailoring strategies to risk groups with underlying medical conditions.