ABSTRACT
ANTECEDENTES Y OBJETIVO Tras 3 años de pandemia, la OMS ha declarado que el COVID-19 no constituye una Emergencia de Salud Pública de Importancia Internacional. En Chile, la Comisión Nacional de Respuesta Pandémica del Ministerio de Salud se ha propuesto reevaluar las medidas de aislamiento y las licencias laborales de casos positivos por COVID-19, para lo cual ha solicitado la presente Síntesis Rápida de Evidencia. METODOLOGÍA Se realizó una estrategia de búsqueda amplia en EMBASE y MEDLINE, a través de OVID, y una búsqueda específica en GOOGLE, sin filtrar por estudios primarios o secundarios. Se identificaron 2.128 referencias, de las cuales se incluyeron 3 estudios tras eliminar los duplicados y aplicar los criterios de inclusión y exclusión. Se utiliza la metodología de la certeza de evidencia GRADE. RESULTADOS Se describen normativas de 12 países - La variante ómicron tiene un periodo medio de contagio de 3,6 días, IC 95%: 3,5 a 6,6 días (certeza de la evidencia alta). - El 81% de los contagios ocurren antes del 5to día desde el inicio de síntomas (certeza de la evidencia alta). - No se identificó evidencia respecto al impacto del aislamiento obligatorio en la morbi-mortalidad asociada al COVID-19, en los estudios incluidos.
Subject(s)
Social Isolation , Chile , Epidemiology , Disease Transmission, Infectious , World Health Organization , Serial Infection IntervalABSTRACT
Highly pathogenic avian influenza viruses (HPAIVs) of the Goose/Guangdong (Gs/Gd) lineage are an emerging threat to wild birds. In the 2016-2017 H5N8 outbreak, unexplained variability was observed in susceptible species, with some reports of infected birds dying in high numbers and other reports of apparently subclinical infections. This experimental study was devised to test the hypothesis that previous infection with a less-virulent HPAIV (i.e., 2014 H5N8) provides long-term immunity against subsequent infection with a more-virulent HPAIV (i.e., 2016 H5N8). Therefore, two species of wild ducks-the more-susceptible tufted duck (Aythya fuligula) and the more-resistant mallard (Anas platyrhynchos)-were serially inoculated, first with 2014 H5N8 and after 9 months with 2016 H5N8. For both species, a control group of birds was first sham inoculated and after 9 months inoculated with 2016 H5N8. Subsequent infection with the more-virulent 2016 H5N8 caused no clinical signs in tufted ducks that had previously been infected with 2014 H5N8 (n = 6) but caused one death in tufted ducks that had been sham inoculated (n = 7). In mallards, 2016 H5N8 infection caused significant body weight loss in previously sham-inoculated birds (n = 8) but not in previously infected birds (n = 7). IMPORTANCE This study showed that ducks infected with a less-virulent HPAIV developed immunity that was protective against a subsequent infection with a more-virulent HPAIV 9 months later. Following 2014 H5N8 infection, the proportion of birds with detectable influenza nucleoprotein antibody declined from 100% (8/8) in tufted ducks and 78% (7/9) in mallards after 1 month to 33% (2/6) in tufted ducks and 29% (2/7) in mallards after 9 months. This finding helps predict the expected impact that an HPAIV outbreak may have on wild bird populations, depending on whether they are immunologically naive or have survived previous infection with HPAIV.
Subject(s)
Animals, Wild , Influenza A Virus, H5N8 Subtype , Influenza in Birds , Animals , Antibodies, Viral/blood , Antibodies, Viral/immunology , Ducks , Influenza A Virus, H5N8 Subtype/immunology , Influenza in Birds/immunology , Influenza in Birds/virology , Serial Infection IntervalABSTRACT
The B.1.1.529 (Omicron) variant, first detected in November 2021, was responsible for a surge in U.S. infections with SARS-CoV-2, the virus that causes COVID-19, during December 2021-January 2022 (1). To investigate the effectiveness of prevention strategies in household settings, CDC partnered with four U.S. jurisdictions to describe Omicron household transmission during November 2021-February 2022. Persons with sequence-confirmed Omicron infection and their household contacts were interviewed. Omicron transmission occurred in 124 (67.8%) of 183 households. Among 431 household contacts, 227 were classified as having a case of COVID-19 (attack rate [AR] = 52.7%). The ARs among household contacts of index patients who had received a COVID-19 booster dose, of fully vaccinated index patients who completed their COVID-19 primary series within the previous 5 months, and of unvaccinated index patients were 42.7% (47 of 110), 43.6% (17 of 39), and 63.9% (69 of 108), respectively. The AR was lower among household contacts of index patients who isolated (41.2%, 99 of 240) compared with those of index patients who did not isolate (67.5%, 112 of 166) (p-value <0.01). Similarly, the AR was lower among household contacts of index patients who ever wore a mask at home during their potentially infectious period (39.5%, 88 of 223) compared with those of index patients who never wore a mask at home (68.9%, 124 of 180) (p-value <0.01). Multicomponent COVID-19 prevention strategies, including up-to-date vaccination, isolation of infected persons, and mask use at home, are critical to reducing Omicron transmission in household settings.
Subject(s)
COVID-19/transmission , SARS-CoV-2 , Adolescent , Adult , Aged , COVID-19/epidemiology , Child , Child, Preschool , Contact Tracing , Family Characteristics , Female , Humans , Incidence , Infant , Male , Middle Aged , Serial Infection Interval , United States/epidemiology , VaccinationABSTRACT
To clarify transmissibility of the severe acute respiratory syndrome coronavirus 2 Omicron variant, we determined serial intervals and secondary attack rates among household contacts in South Korea. Mean serial interval for 12 transmission pairs was 2.9 days, and secondary attack rate among 25 households was 50.0%, raising concern about a rapid surge in cases.
