The impact of COVID-19 nonpharmaceutical interventions on the future dynamics of endemic infections.

Nonpharmaceutical interventions (NPIs) have been employed to reduce the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), yet these measures are already having similar effects on other directly transmitted, endemic diseases. Disruptions to the seasonal transmission patterns of these diseases may have consequences for the timing and severity of future outbreaks. Here we consider the implications of SARS-CoV-2 NPIs for two endemic infections circulating in the United States of America: respiratory syncytial virus (RSV) and seasonal influenza. Using laboratory surveillance data from 2020, we estimate that RSV transmission declined by at least 20% in the United States at the start of the NPI period. We simulate future trajectories of both RSV and influenza, using an epidemic model. As susceptibility increases over the NPI period, we find that substantial outbreaks of RSV may occur in future years, with peak outbreaks likely occurring in the winter of 2021-2022. Longer NPIs, in general, lead to larger future outbreaks although they may display complex interactions with baseline seasonality. Results for influenza broadly echo this picture, but are more uncertain; future outbreaks are likely dependent on the transmissibility and evolutionary dynamics of circulating strains.

Polyunsaturated fatty acids from Phyllocaulis boraceiensis mucus block the replication of influenza virus.

Influenza viruses cause worldwide outbreaks and pandemics in humans and animals every year with considerable morbidity and mortality. The molecular diversity of secondary metabolites extracted from mollusks is a good alternative for the discovery of novel bioactive compounds with unique structures and diverse biological activities. Phyllocaulis boraceiensis is a hermaphroditic slug that exudes mucus, in which was detected hydroxy polyunsaturated fatty acids that exhibited potent antiviral activity against measles virus. The objective of this study was to evaluate this property against Influenza viruses. Cell viability and toxicity of the mucus were evaluated on Madin-Darby canine kidney (MDCK) cells by MTT assay. Antiviral activity from mucus against influenza viruses was carried out by determination of the virus infection dose and by immunofluorescence assays. The crude mucus and its fractions exhibited low cytotoxicity on MDCK cells. A significant inhibition of viral replication, reduced by the order of eight times, was observed in influenza-induced cytopathic effect. In immunofluorescence assay was observed a decrease of more than 80% of the viral load on infected MDCK cell treated with mucus and its fractions. The viral glycoproteins hemagglutinin and neuraminidase located on the surface of the virus are crucial for the replications and infectivity of the influenza virus. Some authors demonstrated that lipids, such as, polyunsaturated fatty acids exhibited multiple roles in antiviral innate and adaptive responses, control of inflammation, and in the development of antiviral therapeutics. As corroborated by other studies, hydroxy polyunsaturated fatty acids interfered with the binding of influenza virus on host cell receptor and reduced viral titers. The results obtained indicated that polyunsaturated fatty acids from P. boraceiensis crude mucus and fractions 39 exerted antiviral activity against influenza virus.

The role of influenza and parainfluenza infections in nasopharyngeal pneumococcal acquisition among young children.

BACKGROUND: Animal models suggest that influenza infection favors nasopharyngeal acquisition of pneumococci. We assessed this relationship with influenza and other respiratory viruses in young children. METHODS: A case-control study was nested within a prospective cohort study of acute respiratory illness (ARI) in Andean children <3 years of age (RESPIRA-PERU study). Weekly household visits were made to identify ARI and obtain nasal swabs for viral detection using real-time reverse-transcription polymerase chain reaction. Monthly nasopharyngeal (NP) samples were obtained to assess pneumococcal colonization. We determined whether specific respiratory viral ARI episodes occurring within the interval between NP samples increased the risk of NP acquisition of new pneumococcal serotypes. RESULTS: A total of 729 children contributed 2128 episodes of observation, including 681 pneumococcal acquisition episodes (new serotype, not detected in prior sample), 1029 nonacquisition episodes (no colonization or persistent colonization with the same serotype as the prior sample), and 418 indeterminate episodes. The risk of pneumococcal acquisition increased following influenza-ARI (adjusted odds ratio [AOR], 2.19; 95% confidence interval [CI], 1.02-4.69) and parainfluenza-ARI (AOR, 1.86; 95% CI, 1.15-3.01), when compared with episodes without ARI. Other viral infections (respiratory syncytial virus, human metapneumovirus, human rhinovirus, and adenovirus) were not associated with acquisition. CONCLUSIONS: Influenza and parainfluenza ARIs appeared to facilitate pneumococcal acquisition among young children. As acquisition increases the risk of pneumococcal diseases, these observations are pivotal in our attempts to prevent pneumococcal disease.

Impact of home environment interventions on the risk of influenza-associated ARI in Andean children: observations from a prospective household-based cohort study.

BACKGROUND: The Respiratory Infections in Andean Peruvian Children (RESPIRA-PERU) study enrolled children who participated in a community-cluster randomized trial of improved stoves, solar water disinfection, and kitchen sinks (IHIP trial) and children from additional Andean households. We quantified the burden of influenza-associated acute respiratory illness (ARI) in this household-based cohort. METHODS: From May 2009 to September 2011, we conducted active weekly ARI surveillance in 892 children age <3 years, of whom 272 (30.5%) had participated in the IHIP trial. We collected nasal swabs during ARI, tested for influenza and other respiratory viruses by RT-PCR, and determined influenza incidence and risk factors using mixed-effects regression models. RESULTS: The overall incidence of influenza-associated ARI was 36.6/100 child-years; incidence of influenza A, B, and C was 20.5, 8.7, and 5.2/100 child-years, respectively. Influenza C was associated with fewer days of subjective fever (median 1 vs. 2) and malaise (median 0 vs. 2) compared to influenza A. Non-influenza ARI also resulted in fewer days of fever and malaise, and fewer healthcare visits than influenza A-associated ARI. Influenza incidence varied by calendar year (80% occurred in the 2010 season) and IHIP trial participation. Among households that participated in the IHIP trial, influenza-associated ARI incidence was significantly lower in intervention than in control households (RR 0.40, 95% CI: 0.20-0.82). CONCLUSIONS: Influenza burden is high among Andean children. ARI associated with influenza A and B had longer symptom duration and higher healthcare utilization than influenza C-associated ARI or non-influenza ARI. Environmental community interventions may reduce influenza morbidity.

Full inactivation of human influenza virus by high hydrostatic pressure preserves virus structure and membrane fusion while conferring protection to mice against infection.

Whole inactivated vaccines (WIVs) possess greater immunogenicity than split or subunit vaccines, and recent studies have demonstrated that WIVs with preserved fusogenic activity are more protective than non-fusogenic WIVs. In this work, we describe the inactivation of human influenza virus X-31 by high hydrostatic pressure (HHP) and analyze the effects on the structure by spectroscopic measurements, light scattering, and electron microscopy. We also investigated the effects of HHP on the glycoprotein activity and fusogenic activity of the viral particles. The electron microscopy data showed pore formation on the viral envelope, but the general morphology was preserved, and small variations were seen in the particle structure. The activity of hemagglutinin (HA) during the process of binding and fusion was affected in a time-dependent manner, but neuraminidase (NA) activity was not affected. Infectious activity ceased after 3 hours of pressurization, and mice were protected from infection after being vaccinated. Our results revealed full viral inactivation with overall preservation of viral structure and maintenance of fusogenic activity, thereby conferring protection against infection. A strong response consisting of serum immunoglobulin IgG1, IgG2a, and serum and mucosal IgA was also detected after vaccination. Thus, our data strongly suggest that applying hydrostatic pressure may be an effective method for developing new vaccines against influenza A as well as other viruses.

Influenza

La influenza es una enfermedad aguda respiratoria, producida por un virus Orthomyxo, de muy fácil y rápida transmisión aérea, que tiene la característica de modificarse biológicamente cada 10 a 12 años, emergiendo con cambios en las estructuras correspondientes a la hemaglutinina y la neuraminidasa, lo que tiene importancia en la epidemiología de la enfermedad debido a la posibilidad de infección de los individuos que previamente hayan sido infectados. La influenza tiene un período de incubación clínico de dos a tres días. Se presenta en brotes epidémicos y causa una alta morbilidad entre la población general. Los grupos de alto riesgo como los enfermos crónicos pulmonares, los que tienen enfermedades cardivasculares, los inmunocomprometidos, los niños y los ancianos, son los que tienen mayor mortalidad que puede llegar hasta el 5 por ciento. Existen tratamientos como el clorhidrato de amantadina y la rimantadina y también se dispone de una vacuna que es producida periódicamente en concordancia con los virus que están circulando en el orbe; contiene una mezcla de virus A y B. En la actualidad se ha aislado por el Instituto Nacional de Salud, el virus A de la unfluenza H3N2 de pacientes de varias ciudades del país.

Actividad del virus de influenza humana en Medellín, Colombia, 1990-1993

Para determinar el virus de influenza en Medellín y contribuir al programa de la Organización Mundial de la Salud (OMS), sobre la investigación de esta enfermedad, se realizó entre 1990-1993 un estudio serológico y virológico en población sana y en pacientes con infección respiratoria aguda (IRA), respectivamente. En 1991 y 1992 se detectó un aumento en el porcentaje de individuos con anticuerpos contra el virus A/Taiwan/1/86 (H1N1). Este porcentaje disminuyó en el año 1993, pero en este mismo año se presentó el mayor número de individuos con anticuerpos contra otras dos cepas del mismo tipo viral: A/Sichuan/2/87 (HGRX -97) y A/Shangai/16/89 (H3N2). También en los primeros meses de 1993 se encontró un porcentaje de individuos sanos con anticuerpos contra el virus A/Beijing/353/89 (H3N2), algo no detectado en el año anterior. Igualmente en el mes de enero de 1993 se aisló un virus A/Beijing/353/89, semejante al que circuló en Estados Unidos en 1992 y 1993. Para el virus de influenza tipo B, no se hallaron anticuerpos contra las cepas estudiadas: B/Victoria/2/87 y B/Panamá/45/90. No se descarta la posibilidad de que haya circulado otra cepa B diferente, que no pudo ser detectado. También se incluyó la búsqueda de anticuerpos contra virus de influenza humana, en cerdos post-infección respiratoria aguda; los resultados fueron negativos. El presente estudio nos muestra la circulación reciente, en muestro medio,de varias cepas de influenza tipo A