Risk Factors and Attack Rates of Seasonal Influenza Infection: Results of the Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance (SHIVERS) Seroepidemiologic Cohort Study.

Background: Understanding the attack rate of influenza infection and the proportion who become ill by risk group is key to implementing prevention measures. While population-based studies of antihemagglutinin antibody responses have been described previously, studies examining both antihemagglutinin and antineuraminidase antibodies are lacking. Methods: In 2015, we conducted a seroepidemiologic cohort study of individuals randomly selected from a population in New Zealand. We tested paired sera for hemagglutination inhibition (HAI) or neuraminidase inhibition (NAI) titers for seroconversion. We followed participants weekly and performed influenza polymerase chain reaction (PCR) for those reporting influenza-like illness (ILI). Results: Influenza infection (either HAI or NAI seroconversion) was found in 321 (35% [95% confidence interval, 32%-38%]) of 911 unvaccinated participants, of whom 100 (31%) seroconverted to NAI alone. Young children and Pacific peoples experienced the highest influenza infection attack rates, but overall only a quarter of all infected reported influenza PCR-confirmed ILI, and one-quarter of these sought medical attention. Seroconversion to NAI alone was higher among children aged <5 years vs those aged ≥5 years (14% vs 4%; P < .001) and among those with influenza B vs A(H3N2) virus infections (7% vs 0.3%; P < .001). Conclusions: Measurement of antineuraminidase antibodies in addition to antihemagglutinin antibodies may be important in capturing the true influenza infection rates.

The cost of influenza-associated hospitalizations and outpatient visits in Kenya.

BACKGROUND: We estimated the cost-per-episode and the annual economic burden associated with influenza in Kenya. METHODS: From July 2013-August 2014, we recruited patients with severe acute respiratory illness (SARI) or influenza-like illness (ILI) associated with laboratory-confirmed influenza from 5 health facilities. A structured questionnaire was used to collect direct costs (medications, laboratory investigations, hospital bed fees, hospital management costs, transportation) and indirect costs (productivity losses) associated with an episode of influenza. We used published incidence of laboratory-confirmed influenza associated with SARI and ILI, and the national population census data from 2014, to estimate the annual national number of influenza-associated hospitalizations and outpatient visits and calculated the annual economic burden by multiplying cases by the mean cost. RESULTS: We enrolled 275 patients (105 inpatients and 170 outpatients). The mean cost-per-episode of influenza was US$117.86 (standard deviation [SD], 88.04) among inpatients; US$114.25 (SD, 90.03) for children < 5 years, and US$137.45 (SD, 76.24) for persons aged ≥5 years. Among outpatients, the mean cost-per-episode of influenza was US$19.82 (SD, 27.29); US$21.49 (SD, 31.42) for children < 5 years, and US$16.79 (SD, 17.30) for persons aged ≥5 years. National annual influenza-associated cost estimates ranged from US$2.96-5.37 million for inpatients and US$5.96-26.35 million for outpatients. CONCLUSIONS: Our findings highlight influenza as causing substantial economic burden in Kenya. Further studies may be warranted to assess the potential benefit of targeted influenza vaccination strategies.

Epidemiology of influenza in West Africa after the 2009 influenza A(H1N1) pandemic, 2010-2012.

BACKGROUND: Over the last decade, capacity for influenza surveillance and research in West Africa has strengthened. Data from these surveillance systems showed influenza A(H1N1)pdm09 circulated in West Africa later than in other regions of the continent. METHODS: We contacted 11 West African countries to collect information about their influenza surveillance systems (number of sites, type of surveillance, sampling strategy, populations sampled, case definitions used, number of specimens collected and number of specimens positive for influenza viruses) for the time period January 2010 through December 2012. RESULTS: Of the 11 countries contacted, 8 responded: Burkina Faso, Cote d'Ivoire, Mali, Mauritania, Niger, Nigeria, Sierra Leone and Togo. Countries used standard World Health Organization (WHO) case definitions for influenza-like illness (ILI) and severe acute respiratory illness (SARI) or slight variations thereof. There were 70 surveillance sites: 26 SARI and 44 ILI. Seven countries conducted SARI surveillance and collected 3114 specimens of which 209 (7%) were positive for influenza viruses. Among influenza-positive SARI patients, 132 (63%) were influenza A [68 influenza A(H1N1)pdm09, 64 influenza A(H3N2)] and 77 (37%) were influenza B. All eight countries conducted ILI surveillance and collected 20,375 specimens, of which 2278 (11%) were positive for influenza viruses. Among influenza-positive ILI patients, 1431 (63%) were influenza A [820 influenza A(H1N1)pdm09, 611 influenza A(H3N2)] and 847 (37%) were influenza B. A majority of SARI and ILI case-patients who tested positive for influenza (72% SARI and 59% ILI) were children aged 0-4 years, as were a majority of those enrolled in surveillance. The seasonality of influenza and the predominant influenza type or subtype varied by country and year. CONCLUSIONS: Influenza A(H1N1)pdm09 continued to circulate in West Africa along with influenza A(H3N2) and influenza B during 2010-2012. Although ILI surveillance systems produced a robust number of samples during the study period, more could be done to strengthen surveillance among hospitalized SARI case-patients. Surveillance systems captured young children but lacked data on adults and the elderly. More data on risk groups for severe influenza in West Africa are needed to help shape influenza prevention and clinical management policies and guidelines.

Incidence of medically attended influenza among residents of Shai-Osudoku and Ningo-Prampram Districts, Ghana, May 2013 - April 2015.

BACKGROUND: Influenza vaccination is recommended by the World Health Organization for high risk groups, yet few data exist on influenza disease burden in West Africa. METHODS: We estimated medically attended influenza-associated illness rates among residents of Shai-Osudoku and Ningo Pram-Pram Districts (SONPD), Ghana. From May 2013 to April 2015, we conducted prospective surveillance for severe acute respiratory illness (SARI) and influenza-like illness (ILI) in 17 health facilities. In 2015, we conducted a retrospective assessment at an additional 18 health facilities to capture all SONPD SARI and ILI patients during the study period. We applied positivity rates to those not tested to estimate total influenza cases. RESULTS: Of 612 SARI patients tested, 58 (9%) were positive for influenza. The estimated incidence of influenza-associated SARI was 30 per 100,000 persons (95% CI: 13-84). Children aged 0 to 4 years had the highest influenza-associated SARI incidence (135 per 100,000 persons, 95% CI: 120-152) and adults aged 25 to 44 years had the lowest (3 per 100,000 persons, 95% CI: 1-7) (p < 0.01). Of 2,322 ILI patients tested, 407 (18%) were positive for influenza. The estimated incidence of influenza-associated ILI was 844 per 100,000 persons (95% CI: 501-1,099). The highest incidence of influenza-associated ILI was also among children aged 0 to 4 years (3,448 per 100,000 persons, 95% CI: 3,727 - 3,898). The predominant circulating subtype during May to December 2013 and January to April 2015 was influenza A(H3N2) virus, and during 2014 influenza B virus was the predominant circulating type. CONCLUSIONS: Influenza accounted for 9% and 18% of medically attended SARI and ILI, respectively. Rates were substantive among young children and suggest the potential value of exploring the benefits of influenza vaccination in Ghana, particularly in this age group.

Severe Acute Respiratory Illness Deaths in Sub-Saharan Africa and the Role of Influenza: A Case Series From 8 Countries.

BACKGROUND: Data on causes of death due to respiratory illness in Africa are limited. METHODS: From January to April 2013, 28 African countries were invited to participate in a review of severe acute respiratory illness (SARI)-associated deaths identified from influenza surveillance during 2009-2012. RESULTS: Twenty-three countries (82%) responded, 11 (48%) collect mortality data, and 8 provided data. Data were collected from 37 714 SARI cases, and 3091 (8.2%; range by country, 5.1%-25.9%) tested positive for influenza virus. There were 1073 deaths (2.8%; range by country, 0.1%-5.3%) reported, among which influenza virus was detected in 57 (5.3%). Case-fatality proportion (CFP) was higher among countries with systematic death reporting than among those with sporadic reporting. The influenza-associated CFP was 1.8% (57 of 3091), compared with 2.9% (1016 of 34 623) for influenza virus-negative cases (P < .001). Among 834 deaths (77.7%) tested for other respiratory pathogens, rhinovirus (107 [12.8%]), adenovirus (64 [6.0%]), respiratory syncytial virus (60 [5.6%]), and Streptococcus pneumoniae (57 [5.3%]) were most commonly identified. Among 1073 deaths, 402 (37.5%) involved people aged 0-4 years, 462 (43.1%) involved people aged 5-49 years, and 209 (19.5%) involved people aged ≥50 years. CONCLUSIONS: Few African countries systematically collect data on outcomes of people hospitalized with respiratory illness. Stronger surveillance for deaths due to respiratory illness may identify risk groups for targeted vaccine use and other prevention strategies.

Influenza vaccines and influenza antiviral drugs in Africa: are they available and do guidelines for their use exist?

BACKGROUND: Influenza viruses cause significant morbidity and mortality in Africa, particularly among high-risk groups, but influenza vaccines and antiviral drugs may not be commonly available and used. The main aim of this study was to determine the availability and use of influenza vaccines and antiviral drugs as well as to describe existing related guidelines and policies in Africa. METHODS: A self-administered survey was distributed among key influenza experts in 40 African countries. RESULTS: Of the 40 countries surveyed, 31 (78%) responded; 14/31 (45%) reported availability of seasonal influenza vaccine, and 19/31 (65%) reported availability of antiviral drugs for the treatment of influenza. Vaccine coverage data were only available for 4/14 (29%) countries that reported availability of seasonal influenza vaccine and ranged from <0.5% to 2% of the population. CONCLUSIONS: Influenza vaccines and antiviral drugs are available in many countries in Africa but coverage estimates are low and remain largely unknown. Describing the local burden of disease and identifying funding are essential to encourage countries to use influenza vaccine more widely.

Influenza surveillance in 15 countries in Africa, 2006-2010.

BACKGROUND: In response to the potential threat of an influenza pandemic, several international institutions and governments, in partnership with African countries, invested in the development of epidemiologic and laboratory influenza surveillance capacity in Africa and the African Network of Influenza Surveillance and Epidemiology (ANISE) was formed. METHODS: We used a standardized form to collect information on influenza surveillance system characteristics, the number and percent of influenza-positive patients with influenza-like illness (ILI), or severe acute respiratory infection (SARI) and virologic data from countries participating in ANISE. RESULTS: Between 2006 and 2010, the number of ILI and SARI sites in 15 African countries increased from 21 to 127 and from 2 to 98, respectively. Children 0-4 years accounted for 48% of all ILI and SARI cases of which 22% and 10%, respectively, were positive for influenza. Influenza peaks were generally discernible in North and South Africa. Substantial cocirculation of influenza A and B occurred most years. CONCLUSIONS: Influenza is a major cause of respiratory illness in Africa, especially in children. Further strengthening influenza surveillance, along with conducting special studies on influenza burden, cost of illness, and role of other respiratory pathogens will help detect novel influenza viruses and inform and develop targeted influenza prevention policy decisions in the region.

Multi-decade national cohort identifies adverse pregnancy and birth outcomes associated with acute respiratory illness hospitalisations during the influenza season.

BACKGROUND: Despite the World Health Organization (WHO) recommendation that pregnant women be prioritised for seasonal influenza vaccination, coverage in the Western Pacific Region remains low. Our goal was to provide additional data for the Western Pacific Region about the value of maternal influenza vaccination to pregnant women and their families. METHODS: We conducted a 16-year retrospective cohort to evaluate risks associated with influenza-associated maternal acute respiratory infection (ARI) in New Zealand. ARI hospitalisations during the May to September influenza season were identified using select ICD-10-AM primary and secondary discharge codes from chapter J00-J99 (diseases of the respiratory system). Cox proportional hazards models were used to calculate crude and adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). RESULTS: We identified 822,391 pregnancies among New Zealand residents between 2003 and 2018; 5095 (0.6%) had ≥1 associated ARI hospitalisation during the influenza season; these pregnancies were at greater risk of preterm birth (aHR 1.50, 95% CI 1.39-1.61) and low birthweight (aHR 1.64, 95% CI 1.51-1.79) than pregnancies without such hospitalisations. We did not find an association between maternal ARI hospitalisation and fetal death (aHR 0.96, 95% CI 0.69-1.34) during the influenza season. Maternal influenza vaccination was associated with reduced risk of preterm birth (aHR 0.79, 95% CI 0.77-0.82), low birthweight (aHR 0.87, 95% CI 0.83-0.90) and fetal death (aHR 0.50%, 95% CI 0.44-0.57). CONCLUSION: In this population-based cohort, being hospitalised for an ARI during the influenza season while pregnant was a risk factor for delivering a preterm or a low birthweight infant and vaccination reduced this risk.

Effect of antipyretics on performance of influenza surveillance in Ghana.

BACKGROUND: The World Health Organization's case definition for influenza-like illness (ILI) includes a measured temperature of ≥38°C. We conducted this study to assess the effect of antipyretics on performance of ILI surveillance in Ghana. METHODS: A cross-sectional study was conducted in two districts of Ghana from September 2013 to May 2014. We collected epidemiological data and respiratory specimens from an expanded ILI case definition, which included patients presenting to health facilities with measured temperature ≥38°C or reported fever (but afebrile at the time of evaluation), and cough, with onset in the last 10 days. Specimens were tested for influenza viruses by real time reverse-transcription polymerase chain reaction. RESULTS: Of 321 participants who met our expanded ILI case definition, 236 presented with temperature of <38°C but reported subjective fever. Of these, 17% (39/236) were positive for influenza virus; Of those with fever ≤38°C who took antipyretics, 21%(16/77) were positive for influenza, compared with 14%(23/159) of those who did not take antipyretics. The addition of subjective fever to the standard ILI case definition captured approximately an additional 57% influenza cases but also required testing of approximately four times as many patients. However, including those without fever on presentation that had taken antipyretics found an additional 23% of Influenza cases and only two times as much testing. CONCLUSION: Depending on the goals of surveillance (monitoring virus circulation or determining disease burden) and available resources, a more sensitive case definition including subjective fever and history of use of antipyretics may be warranted.

Severe Acute Respiratory Syndrome Coronavirus 2 Neutralizing Antibody Responses After Community Infections in Children and Adults.

Background: We compared postinfection severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibody (nAb) responses among children and adults while the D614G-like strain and Alpha, Iota, and Delta variants circulated. Methods: During August 2020-October 2021, households with adults and children were enrolled and followed in Utah, New York City, and Maryland. Participants collected weekly respiratory swabs that were tested for SARS-CoV-2 and had sera collected during enrollment and follow-up. Sera were tested for SARS-CoV-2 nAb by pseudovirus assay. Postinfection titers were characterized with biexponential decay models. Results: Eighty participants had SARS-CoV-2 infection during the study (47 with D614G-like virus, 17 with B.1.1.7, and 8 each with B.1.617.2 and B.1.526 virus). Homologous nAb geometric mean titers (GMTs) trended higher in adults (GMT = 2320) versus children 0-4 (GMT = 425, P = .33) and 5-17 years (GMT = 396, P = .31) at 1-5 weeks postinfection but were similar from 6 weeks. Timing of peak titers was similar by age. Results were consistent when participants with self-reported infection before enrollment were included (n = 178). Conclusions: The SARS-CoV-2 nAb titers differed in children compared to adults early after infection but were similar by 6 weeks postinfection. If postvaccination nAb kinetics have similar trends, vaccine immunobridging studies may need to compare nAb responses in adults and children 6 weeks or more after vaccination.

Factors Associated with Intention to Vaccinate Children 0-11 Years of Age Against COVID-19.

BACKGROUND: Millions of children have tested positive for SARS-CoV-2, and over 1000 children have died in the US. However, vaccination rates for children 5 to 11 years old are low. METHODS: Starting in August 2020, we conducted a prospective SARS-CoV-2 household surveillance study in Spanish and English-speaking households in New York City and Utah. From October 21 to 25, 2021, we asked caregivers about their likelihood of getting COVID-19 vaccine for their child, and reasons that they might or might not vaccinate that child. We compared intent to vaccinate by site, demographic characteristics, SARS-CoV-2 infection detected by study surveillance, and parents' COVID-19 vaccination status using Chi-square tests and a multivariable logistic regression model, accounting for within-household clustering. RESULTS: Among parents or caregivers of 309 children (0 to 11 years) in 172 households, 87% were very or somewhat likely to intend to vaccinate their child. The most prevalent reasons for intending to vaccinate were to protect family and friends and the community; individual prevention was mentioned less often. The most prevalent reasons for not intending to vaccinate were side effect concerns and wanting to wait and see.In multivariable analysis, parents had much lower odds of intending to vaccinate if someone in the household had tested SARS-CoV-2-positive during the study (adjusted odds ratio = 0.09; 95% confidence interval, 0.03-0.3). CONCLUSION: This study highlighted several themes for clinicians and public health officials to consider including the importance and safety of vaccination for this age-group even if infected previously, and the benefits of vaccination to protect family, friends, and community.

Sensitivity and specificity of surveillance case definitions in detection of influenza and respiratory syncytial virus among hospitalized patients, New Zealand, 2012-2016.

BACKGROUND: The WHO is exploring the value of adding RSV testing to existing influenza surveillance systems to inform RSV control programs. We evaluate the usefulness of four commonly used influenza surveillance case-definitions for influenza and RSV surveillance. METHODS: SHIVERS, a multi-institutional collaboration, conducted surveillance for influenza and RSV in four New Zealand hospitals. Nurses reviewed admission logs, enrolled patients with suspected acute respiratory infections (ARI), and obtained nasopharyngeal swabs for RT-PCR. We compared the performance characteristics for identifying laboratory-confirmed influenza and RSV severe acute respiratory infection (SARI), defined as persons admitted with measured or reported fever and cough within 10 days of illness, to three other case definitions: 1. reported fever and cough or shortness of breath, 2. cough and shortness of breath, or 3. cough. RESULTS: During April-September 2012-2016, SHIVERS identified 16,055 admissions with ARI; of 6374 cases consented and tested for influenza or RSV, 5437 (85%) had SARI and 937 (15%) did not. SARI had the highest specificity in detecting influenza (40.6%) and RSV (40.8%) but the lowest sensitivity (influenza 78.8%, RSV 60.3%) among patients of all ages. Cough or shortness of breath had the highest sensitivity (influenza 99.3%, RSV 99.9%) but the lowest specificity (influenza 1.6%, RSV 1.9%). SARI sensitivity among children aged <3 months was 60.8% for influenza and 43.6% for RSV-both lower than in other age groups. CONCLUSIONS: While SARI had the highest specificity, its sensitivity was limited, especially among children aged <3 months. Cough or shortness of breath was the most sensitive.

SARS-CoV-2 Genomic Diversity in Households Highlights the Challenges of Sequence-Based Transmission Inference.

The reliability of sequence-based inference of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is not clear. Sequence data from infections among household members can define the expected genomic diversity of a virus along a defined transmission chain. SARS-CoV-2 cases were identified prospectively among 2,369 participants in 706 households. Specimens with a reverse transcription-PCR cycle threshold of ≤30 underwent whole-genome sequencing. Intrahost single-nucleotide variants (iSNV) were identified at a ≥5% frequency. Phylogenetic trees were used to evaluate the relationship of household and community sequences. There were 178 SARS-CoV-2 cases in 706 households. Among 147 specimens sequenced, 106 yielded a whole-genome consensus with coverage suitable for identifying iSNV. Twenty-six households had sequences from multiple cases within 14 days. Consensus sequences were indistinguishable among cases in 15 households, while 11 had ≥1 consensus sequence that differed by 1 to 2 mutations. Sequences from households and the community were often interspersed on phylogenetic trees. Identification of iSNV improved inference in 2 of 15 households with indistinguishable consensus sequences and in 6 of 11 with distinct ones. In multiple-infection households, whole-genome consensus sequences differed by 0 to 1 mutations. Identification of shared iSNV occasionally resolved linkage, but the low genomic diversity of SARS-CoV-2 limits the utility of "sequence-only" transmission inference. IMPORTANCE We performed whole-genome sequencing of SARS-CoV-2 from prospectively identified cases in three longitudinal household cohorts. In a majority of multi-infection households, SARS-CoV-2 consensus sequences were indistinguishable, and they differed by 1 to 2 mutations in the rest. Importantly, even with modest genomic surveillance of the community (3 to 5% of cases sequenced), it was not uncommon to find community sequences interspersed with household sequences on phylogenetic trees. Identification of shared minority variants only occasionally resolved these ambiguities in transmission linkage. Overall, the low genomic diversity of SARS-CoV-2 limits the utility of "sequence-only" transmission inference. Our work highlights the need to carefully consider both epidemiologic linkage and sequence data to define transmission chains in households, hospitals, and other transmission settings.

Incidence Rates, Household Infection Risk, and Clinical Characteristics of SARS-CoV-2 Infection Among Children and Adults in Utah and New York City, New York.

Importance: Data about the risk of SARS-CoV-2 infection among children compared with adults are needed to inform COVID-19 risk communication and prevention strategies, including COVID-19 vaccination policies for children. Objective: To compare incidence rates and clinical characteristics of SARS-CoV-2 infection among adults and children and estimated household infection risks within a prospective household cohort. Design, Setting, and Participants: Households with at least 1 child aged 0 to 17 years in selected counties in Utah and New York City, New York, were eligible for enrollment. From September 2020 through April 2021, participants self-collected midturbinate nasal swabs for reverse transcription-polymerase chain reaction testing for SARS-CoV-2 and responded to symptom questionnaires each week. Participants also self-collected additional respiratory specimens with onset of COVID-19-like illness. For children unable to self-collect respiratory specimens, an adult caregiver collected the specimens. Main Outcomes and Measures: The primary outcome was incident cases of any SARS-CoV-2 infection, including asymptomatic and symptomatic infections. Additional measures were the asymptomatic fraction of infection calculated by dividing incidence rates of asymptomatic infection by rates of any infection, clinical characteristics of infection, and household infection risks. Primary outcomes were compared by participant age group. Results: A total of 1236 participants in 310 households participated in surveillance, including 176 participants (14%) who were aged 0 to 4 years, 313 (25%) aged 5 to 11 years, 163 (13%) aged 12 to 17 years, and 584 (47%) 18 years or older. Overall incidence rates of SARS-CoV-2 infection were 3.8 (95% CI, 2.4-5.9) and 7.7 (95% CI, 4.1-14.5) per 1000 person-weeks among the Utah and New York City cohorts, respectively. Site-adjusted incidence rates per 1000 person-weeks were similar by age group: 6.3 (95% CI, 3.6-11.0) for children 0 to 4 years, 4.4 (95% CI, 2.5-7.5) for children 5 to 11 years, 6.0 (95% CI, 3.0-11.7) for children 12 to 17 years, and 5.1 (95% CI, 3.3-7.8) for adults (≥18 years). The asymptomatic fractions of infection by age group were 52%, 50%, 45%, and 12% among individuals aged 0 to 4 years, 5 to 11 years, 12 to 17 years, and 18 years or older, respectively. Among 40 households with 1 or more SARS-CoV-2 infections, the mean risk of SARS-CoV-2 infection among all enrolled household members was 52% (range, 11%-100%), with higher risks in New York City compared with Utah (80% [95% CI, 64%-91%] vs 44% [95% CI, 36%-53%]; P < .001). Conclusions and Relevance: In this study, children had similar incidence rates of SARS-CoV-2 infection compared with adults, but a larger proportion of infections among children were asymptomatic.

Impact of Age and Symptom Development on SARS-CoV-2 Transmission in Households With Children-Maryland, New York, and Utah, August 2020-October 2021.

Background: Households are common places for spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We investigated factors associated with household transmission and acquisition of SARS-CoV-2. Methods: Households with children age <18 years were enrolled into prospective, longitudinal cohorts and followed from August 2020 to August 2021 in Utah, September 2020 to August 2021 in New York City, and November 2020 to October 2021 in Maryland. Participants self-collected nasal swabs weekly and with onset of acute illness. Swabs were tested for SARS-CoV-2 using reverse transcription polymerase chain reaction. We assessed factors associated with SARS-CoV-2 acquisition using a multilevel logistic regression adjusted for household size and clustering and SARS-CoV-2 transmission using a logistic regression adjusted for household size. Results: Among 2053 people (513 households) enrolled, 180 people (8.8%; in 76 households) tested positive for SARS-CoV-2. Compared with children age <12 years, the odds of acquiring infection were lower for adults age ≥18 years (adjusted odds ratio [aOR], 0.34; 95% CI, 0.14-0.87); however, this may reflect vaccination status, which protected against SARS-CoV-2 acquisition (aOR, 0.17; 95% CI, 0.03-0.91). The odds of onward transmission were similar between symptomatic and asymptomatic primary cases (aOR, 1.00; 95% CI, 0.35-2.93) and did not differ by age (12-17 years vs <12 years: aOR, 1.08; 95% CI, 0.20-5.62; ≥18 years vs <12 years: aOR, 1.70; 95% CI, 0.52-5.83). Conclusions: Adults had lower odds of acquiring SARS-CoV-2 compared with children, but this association might be influenced by coronavirus disease 2019 (COVID-19) vaccination, which was primarily available for adults and protective against infection. In contrast, all ages, regardless of symptoms and COVID-19 vaccination, had similar odds of transmitting SARS-CoV-2. Our findings underscore the importance of SARS-CoV-2 mitigation measures for persons of all ages.

Detection and Stability of SARS-CoV-2 in Three Self-Collected Specimen Types: Flocked Midturbinate Swab (MTS) in Viral Transport Media, Foam MTS, and Saliva.

Respiratory specimen collection materials shortages hampers severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing. We compared specimen alternatives and evaluated SARS-CoV-2 RNA stability under simulated shipping conditions. We compared concordance of RT-PCR detection of SARS-CoV-2 from flocked midturbinate swabs (MTS) in viral transport media (VTM), foam MTS without VTM, and saliva. Specimens were collected between August 2020 and April 2021 from three prospective cohorts. We compared RT-PCR cycle quantification (Cq) for Spike (S), Nucleocapsid (N), and the Open Reading Frame 1ab (ORF) genes for flocked MTS and saliva specimens tested before and after exposure to a range of storage temperatures (4-30°C) and times (2, 3, and 7 days). Of 1,900 illnesses with ≥2 specimen types tested, 335 (18%) had SARS-CoV-2 detected in ≥1 specimen; 304 (91%) were concordant across specimen types. Among illnesses with SARS-CoV-2 detection, 97% (95% confidence interval [CI]: 94-98%) were positive on flocked MTS, 99% (95% CI: 97-100%) on saliva, and 89% (95% CI: 84-93%) on foam MTS. SARS-CoV-2 RNA was detected in flocked MTS and saliva stored up to 30°C for 7 days. All specimen types provided highly concordant SARS-CoV-2 results. These findings support a range of viable options for specimen types, collection, and transport methods that may facilitate SARS-CoV-2 testing during supply and personnel shortages. IMPORTANCE Findings from this analysis indicate that (1) self-collection of flocked and foam MTS and saliva samples is feasible in both adults and children, (2) foam MTS with VTM and saliva are both viable and reasonable alternatives to traditional flocked MTS in VTM for SARS-CoV-2 detection, and (3) these sample types may be stored and transported at ambient temperatures for up to 7 days without compromising sample quality. These findings support methods of sample collection for SARS-CoV-2 detection that may facilitate widespread community testing in the setting of supply and personnel shortages during the current pandemic.

Incidence of Laboratory-Confirmed Influenza among HIV-Infected versus HIV-Uninfected Individuals in Two Districts of Ghana, 2014 to 2016.

Influenza is known to cause severe respiratory illness in HIV-infected adults, but there are few data describing the relationship between HIV infection and influenza in West African countries such as Ghana. We conducted a prospective cohort study in the Shai-Osudoku and Ningo Prampram districts of Ghana from 2014 to 2016. Beginning May 2014, 266 HIV-infected and 510 HIV-uninfected participants age 18 to 73 years were enrolled and monitored for 12 months. We observed 4 and 11 laboratory-confirmed influenza cases among HIV-infected and HIV-uninfected persons, respectively. The overall rate of laboratory-confirmed influenza among HIV-infected participants was 15.0 per 1,000 person years (PY) (95% CI, 0.3-29.80 per 1,000 PY), whereas that among HIV-uninfected participants was 21.6 per 1,000 PY (95% CI, 8.8-34.3 per 1,000 PY) (incidence density ratio, 0.70; P = 0.56). Our study found no significant difference in the incidence of laboratory-confirmed influenza-associated illness among HIV-infected and HIV-uninfected individuals in Ghana.

Respiratory Virus-related Emergency Department Visits and Hospitalizations Among Infants in New Zealand.

BACKGROUND: Estimates of the contribution of respiratory viruses to emergency department (ED) utilization remain limited. METHODS: We conducted surveillance of infants with acute respiratory infection (ARI) associated ED visits, which then resulted in either hospital admission or discharge home. Seasonal rates of specific viruses stratified by age, ethnicity, and socioeconomic status were estimated for both visits discharged directly from ED and hospitalizations using rates of positivity for each virus. RESULTS: During the 2014-2016 winter seasons, 3585 (66%) of the 5412 ARI ED visits were discharged home directly and 1827 (34%) were admitted to hospital. Among visits tested for all respiratory viruses, 601/1111 (54.1%) of ED-only and 639/870 (73.4%) of the hospital-admission groups were positive for at least one respiratory virus. Overall, respiratory virus-associated ED visit rates were almost twice as high as hospitalizations. Respiratory syncytial virus was associated with the highest ED (34.4 per 1000) and hospitalization rates (24.6 per 1000) among infants. ED visit and hospitalization rates varied significantly by age and virus. Maori and Pacific children had significantly higher ED visit and hospitalization rates for all viruses compared with children of other ethnicities. CONCLUSIONS: Many infants with acute respiratory virus infections are managed in the ED rather than admitted to the hospital. Higher rates of ED-only versus admitted acute respiratory virus infections occur among infants living in lower socioeconomic households, older infants and infants of Maori or Pacific versus European ethnicity. Respiratory virus infections resulting in ED visits should be included in measurements of ARI disease burden.

Timing of respiratory syncytial virus and influenza epidemic activity in five regions of Argentina, 2007-2016.

BACKGROUND: Within-country differences in the timing of RSV and influenza epidemics have not been assessed in Argentina, the eighth largest country in the world by area. OBJECTIVE: We aimed to compare seasonality for RSV and influenza both nationally and in each of the five regions to inform Argentina's prevention and treatment guidelines. METHOD: The Argentine National Laboratories and Health Institutes Administration collected respiratory specimens from clinical practices, outbreak investigations, and respiratory virus surveillance in 2007-2016; these were tested using immunofluorescence or RT-PCR techniques. We calculated weekly percent positive (PP) and defined season onset as >2 consecutive weeks when PP exceeded the annual mean for the respective year and region. Median season measures (onset, offset and peak) and the established mean method were calculated for each virus. RESULTS: An annual median 59 396 specimens were tested for RSV and 60 931 for influenza; 21-29% tested positive for RSV and 2-7% for influenza. National RSV activity began in April; region-specific start weeks varied by 7 weeks. Duration of RSV activity did not vary widely by region (16-18 weeks in duration). National influenza activity started in June; region-specific start weeks varied by 3 weeks. Duration of influenza epidemic activity varied more by region than that of RSV (7-13 weeks in duration). CONCLUSION: In Argentina, RSV and influenza activity overlapped during the winter months. RSV season tended to begin prior to the influenza season, and showed more variation in start week by region. Influenza seasons tended to vary more in duration than RSV seasons.

Influenza vaccine effectiveness in preventing influenza-associated intensive care admissions and attenuating severe disease among adults in New Zealand 2012-2015.

BACKGROUND: Little is known about inactivated influenza vaccine effectiveness (IVE) in preventing very severe disease, including influenza-associated intensive care unit (ICU) admissions. METHODS: The Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance (SHIVERS) project enrolled adults (aged ≥ 18 years) with acute respiratory illness (ARI) in general ward (GW) hospital settings (n = 3034) and ICUs (n = 101) during 2012-2015. IVE was assessed using a test-negative design comparing the odds of influenza vaccination among influenza positives vs. negatives (confirmed by real-time reverse transcription polymerase chain reaction). All models were adjusted for season, weeks from season peak, and a vaccination propensity score. RESULTS: Influenza virus infection was confirmed in 28% of GW hospital and 41% of ICU patients; influenza vaccination was documented for 56% and 41%, respectively. Across seasons, IVE was 37% (95% confidence intervals [CI] = 23-48%) among GW patients and 82% (95% CI = 45-94%) among ICU patients. IVE point estimates were > 70% against ICU influenza and consistently higher than IVE against GW influenza when stratified by season, by virus (sub)types, and for adults with or without chronic medical conditions and for both adults aged <65 and ≥65 years old. Among hospitalized influenza positives, influenza vaccination was associated with a 59% reduction in the odds of ICU admission (aOR = 0.41, 95% CI = 0.18-0.96) and with shorter ICU lengths of stay (LOS), but not with radiograph-confirmed pneumonia or GW hospital LOS. CONCLUSION: Inactivated influenza vaccines prevented influenza-associated ICU admissions, may have higher effectiveness in ICU than GW hospital settings, and appeared to reduce the risk of severe disease among those who are infected despite vaccination.