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1.
MMWR Morb Mortal Wkly Rep ; 69(2): 40-43, 2020 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-31945035

RESUMEN

Multiple genetically distinct influenza B/Victoria lineage viruses have cocirculated in the United States recently, circulating sporadically during the 2018-19 season and more frequently early during the 2019-20 season (1). The beginning of the 2019-20 influenza season in Louisiana was unusually early and intense, with infections primarily caused by influenza B/Victoria lineage viruses. One large pediatric health care facility in New Orleans (facility A) reported 1,268 laboratory-confirmed influenza B virus infections, including 23 hospitalizations from July 31 to November 21, 2019, a time when influenza activity is typically low. During this period, Louisiana also reported one pediatric death associated with influenza B virus infection. An investigation of the influenza B virus infections in Louisiana, including medical and vaccine record abstraction on 198 patients, primarily from facility A, with sporadic cases from other facilities in the state, found that none of the patients had received 2019-20 seasonal influenza vaccine, in part because influenza activity began before influenza vaccination typically occurs. Among 83 influenza B viruses sequenced from 198 patients in Louisiana, 81 (98%) belonged to the recently emerged B/Victoria V1A.3 genetic subclade. Nationally, to date, B/Victoria viruses are the most commonly reported influenza viruses among persons aged <25 years (2). Of the 198 patients in the investigation, 95% were aged <18 years. Although most illnesses were uncomplicated, the number of hospitalizations, clinical complications, and the reported pediatric death in Louisiana serve as a reminder that, even though influenza B viruses are less common than influenza A viruses in most seasons, influenza B virus infection can be severe in children. All persons aged ≥6 months should receive an annual influenza vaccination if they have not already received it (3). Antiviral treatment of influenza is recommended as soon as possible for all hospitalized patients and for outpatients at high risk for influenza complications (including children aged <2 years and persons with underlying medical conditions) (4).


Asunto(s)
Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Gripe Humana/virología , Adolescente , Adulto , Niño , Preescolar , Humanos , Lactante , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Louisiana/epidemiología , Estaciones del Año , Adulto Joven
3.
J Infect Dis ; 221(1): 8-15, 2020 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-31665373

RESUMEN

BACKGROUND: Increased illness due to antigenically drifted A(H3N2) clade 3C.3a influenza viruses prompted concerns about vaccine effectiveness (VE) and vaccine strain selection. We used US virologic surveillance and US Influenza Vaccine Effectiveness (Flu VE) Network data to evaluate consequences of this clade. METHODS: Distribution of influenza viruses was described using virologic surveillance data. The Flu VE Network enrolled ambulatory care patients aged ≥6 months with acute respiratory illness at 5 sites. Respiratory specimens were tested for influenza by means of reverse-transcriptase polymerase chain reaction and were sequenced. Using a test-negative design, we estimated VE, comparing the odds of influenza among vaccinated versus unvaccinated participants. RESULTS: During the 2018-2019 influenza season, A(H3N2) clade 3C.3a viruses caused an increasing proportion of influenza cases. Among 2763 Flu VE Network case patients, 1325 (48%) were infected with A(H1N1)pdm09 and 1350 (49%) with A(H3N2); clade 3C.3a accounted for 977 (93%) of 1054 sequenced A(H3N2) viruses. VE was 44% (95% confidence interval, 37%-51%) against A(H1N1)pdm09 and 9% (-4% to 20%) against A(H3N2); VE was 5% (-10% to 19%) against A(H3N2) clade 3C.3a viruses. CONCLUSIONS: The predominance of A(H3N2) clade 3C.3a viruses during the latter part of the 2018-2019 season was associated with decreased VE, supporting the A(H3N2) vaccine component update for 2019-2020 northern hemisphere influenza vaccines.

4.
MMWR Morb Mortal Wkly Rep ; 68(40): 880-884, 2019 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-31600182

RESUMEN

During May 19-September 28, 2019,* low levels of influenza activity were reported in the United States, with cocirculation of influenza A and influenza B viruses. In the Southern Hemisphere seasonal influenza viruses circulated widely, with influenza A(H3) predominating in many regions; however, influenza A(H1N1)pdm09 and influenza B viruses were predominant in some countries. In late September, the World Health Organization (WHO) recommended components for the 2020 Southern Hemisphere influenza vaccine and included an update to the A(H3N2) and B/Victoria-lineage components. Annual influenza vaccination is the best means for preventing influenza illness and its complications, and vaccination before influenza activity increases is optimal. Health care providers should recommend vaccination for all persons aged ≥6 months who do not have contraindications to vaccination (1).


Asunto(s)
Salud Global/estadística & datos numéricos , Vacunas contra la Influenza/química , Gripe Humana/epidemiología , Vigilancia de la Población , Farmacorresistencia Viral , Humanos , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/virología , Estaciones del Año , Estados Unidos/epidemiología
5.
PLoS One ; 14(9): e0222381, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31513690

RESUMEN

We describe the epidemiological characteristics, pattern of circulation, and geographical distribution of influenza B viruses and its lineages using data from the Global Influenza B Study. We included over 1.8 million influenza cases occurred in thirty-one countries during 2000-2018. We calculated the proportion of cases caused by influenza B and its lineages; determined the timing of influenza A and B epidemics; compared the age distribution of B/Victoria and B/Yamagata cases; and evaluated the frequency of lineage-level mismatch for the trivalent vaccine. The median proportion of influenza cases caused by influenza B virus was 23.4%, with a tendency (borderline statistical significance, p = 0.060) to be higher in tropical vs. temperate countries. Influenza B was the dominant virus type in about one every seven seasons. In temperate countries, influenza B epidemics occurred on average three weeks later than influenza A epidemics; no consistent pattern emerged in the tropics. The two B lineages caused a comparable proportion of influenza B cases globally, however the B/Yamagata was more frequent in temperate countries, and the B/Victoria in the tropics (p = 0.048). B/Yamagata patients were significantly older than B/Victoria patients in almost all countries. A lineage-level vaccine mismatch was observed in over 40% of seasons in temperate countries and in 30% of seasons in the tropics. The type B virus caused a substantial proportion of influenza infections globally in the 21st century, and its two virus lineages differed in terms of age and geographical distribution of patients. These findings will help inform health policy decisions aiming to reduce disease burden associated with seasonal influenza.

6.
MMWR Morb Mortal Wkly Rep ; 68(24): 544-551, 2019 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-31220057

RESUMEN

Influenza activity* in the United States during the 2018-19 season (September 30, 2018-May 18, 2019) was of moderate severity (1). Nationally, influenza-like illness (ILI)† activity began increasing in November, peaked during mid-February, and returned to below baseline in mid-April; the season lasted 21 weeks,§ making it the longest season in 10 years. Illness attributed to influenza A viruses predominated, with very little influenza B activity. Two waves of influenza A were notable during this extended season: influenza A(H1N1)pdm09 viruses from October 2018 to mid-February 2019 and influenza A(H3N2) viruses from February through May 2019. Compared with the 2017-18 influenza season, rates of hospitalization this season were lower for adults, but were similar for children. Although influenza activity is currently below surveillance baselines, testing for seasonal influenza viruses and monitoring for novel influenza A virus infections should continue year-round. Receiving a seasonal influenza vaccine each year remains the best way to protect against seasonal influenza and its potentially severe consequences.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Antivirales/farmacología , Niño , Mortalidad del Niño , Preescolar , Costo de Enfermedad , Farmacorresistencia Viral , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Mortalidad Infantil , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Vacunas contra la Influenza/administración & dosificación , Vacunas contra la Influenza/química , Gripe Humana/mortalidad , Gripe Humana/prevención & control , Gripe Humana/virología , Persona de Mediana Edad , Pacientes Ambulatorios/estadística & datos numéricos , Neumonía/mortalidad , Estaciones del Año , Índice de Severidad de la Enfermedad , Estados Unidos/epidemiología , Adulto Joven
7.
J Infect Dis ; 220(5): 820-829, 2019 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-31053844

RESUMEN

BACKGROUND: The evolution of influenza A viruses results in birth cohorts that have different initial influenza virus exposures. Historically, A/H3 predominant seasons have been associated with more severe influenza-associated disease; however, since the 2009 pandemic, there are suggestions that some birth cohorts experience more severe illness in A/H1 predominant seasons. METHODS: United States influenza virologic, hospitalization, and mortality surveillance data during 2000-2017 were analyzed for cohorts born between 1918 and 1989 that likely had different initial influenza virus exposures based on viruses circulating during early childhood. Relative risk/rate during H3 compared with H1 predominant seasons during prepandemic versus pandemic and later periods were calculated for each cohort. RESULTS: During the prepandemic period, all cohorts had more influenza-associated disease during H3 predominant seasons than H1 predominant seasons. During the pandemic and later period, 4 cohorts had higher hospitalization and mortality rates during H1 predominant seasons than H3 predominant seasons. CONCLUSIONS: Birth cohort differences in risk of influenza-associated disease by influenza A virus subtype can be seen in US influenza surveillance data and differ between prepandemic and pandemic and later periods. As the population ages, the amount of influenza-associated disease may be greater in future H1 predominant seasons than H3 predominant seasons.

8.
MMWR Morb Mortal Wkly Rep ; 68(6): 125-134, 2019 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-30763296

RESUMEN

CDC collects, compiles, and analyzes data on influenza activity and viruses in the United States. During September 30, 2018-February 2, 2019,* influenza activity† in the United States was low during October and November, increased in late December, and remained elevated through early February. As of February 2, 2019, this has been a low-severity influenza season (1), with a lower percentage of outpatient visits for influenza-like illness (ILI), lower rates of hospitalization, and fewer deaths attributed to pneumonia and influenza, compared with recent seasons. Influenza-associated hospitalization rates among children are similar to those observed in influenza A(H1N1)pdm09 predominant seasons; 28 influenza-associated pediatric deaths occurring during the 2018-19 season have been reported to CDC. Whereas influenza A(H1N1)pdm09 viruses predominated in most areas of the country, influenza A(H3N2) viruses have predominated in the southeastern United States, and in recent weeks accounted for a growing proportion of influenza viruses detected in several other regions. Small numbers of influenza B viruses (<3% of all influenza-positive tests performed by public health laboratories) also were reported. The majority of the influenza viruses characterized antigenically are similar to the cell culture-propagated reference viruses representing the 2018-19 Northern Hemisphere influenza vaccine viruses. Health care providers should continue to offer and encourage vaccination to all unvaccinated persons aged ≥6 months as long as influenza viruses are circulating. Finally, regardless of vaccination status, it is important that persons with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for influenza complications be treated with antiviral medications.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Niño , Mortalidad del Niño , Preescolar , Farmacorresistencia Viral , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Mortalidad Infantil , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Vacunas contra la Influenza/química , Gripe Humana/mortalidad , Gripe Humana/prevención & control , Gripe Humana/virología , Persona de Mediana Edad , Pacientes Ambulatorios/estadística & datos numéricos , Neumonía/mortalidad , Prevalencia , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
9.
MMWR Morb Mortal Wkly Rep ; 67(49): 1369-1371, 2018 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-30543604

RESUMEN

Influenza activity in the United States was low during October 2018, and, although it increased slowly during November, activity remains low across most of the country.* During the week ending December 1, 2018, the percentage of outpatient visits for influenza-like illness† (ILI) was equal to the national baseline§ (Figure) and was at or slightly above the region-specific baseline in four of the 10 U.S. Department of Health and Human Services regions¶ (Regions 4 and 7-9). The majority of jurisdictions experienced minimal or low ILI activity since September 30; however, two experienced moderate ILI activity, and two experienced high ILI activity** during the week ending December 1. The percentage of deaths attributed to pneumonia and influenza remains below the epidemic threshold,†† and the rate of influenza-associated hospitalizations remains low. Five laboratory-confirmed, influenza-associated pediatric deaths occurring since September 30 have been reported to CDC. During the week ending December 1, the majority of jurisdictions (40 states, the District of Columbia, Puerto Rico, and U.S. Virgin Islands) reported sporadic or local geographic spread of influenza activity, nine states reported regional activity, and one state reported widespread activity.§§.


Asunto(s)
Gripe Humana/epidemiología , Vigilancia de la Población , Atención Ambulatoria , Humanos , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/prevención & control , Gripe Humana/virología , Estaciones del Año , Estados Unidos/epidemiología
10.
MMWR Morb Mortal Wkly Rep ; 67(42): 1178-1185, 2018 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-30359347

RESUMEN

During May 20-October 13, 2018,* low levels of influenza activity were reported in the United States, with a mix of influenza A and B viruses circulating. Seasonal influenza activity in the Southern Hemisphere was low overall, with influenza A(H1N1)pdm09 predominating in many regions. Antigenic testing of available influenza A and B viruses indicated that no significant antigenic drift in circulating viruses had emerged. In late September, the components for the 2019 Southern Hemisphere influenza vaccine were selected and included an incremental update to the A(H3N2) vaccine virus used in egg-based vaccine manufacturing; no change was recommended for the A(H3N2) component of cell-manufactured or recombinant influenza vaccines. Annual influenza vaccination is the best method for preventing influenza illness and its complications, and all persons aged ≥6 months who do not have contraindications should receive influenza vaccine, preferably before the onset of influenza circulation in their community, which often begins in October and peaks during December-February. Health care providers should offer vaccination by the end of October and should continue to recommend and administer influenza vaccine to previously unvaccinated patients throughout the 2018-19 influenza season (1). In addition, during May 20-October 13, a small number of nonhuman influenza "variant" virus infections† were reported in the United States; most were associated with exposure to swine. Although limited human-to-human transmission might have occurred in one instance, no ongoing community transmission was identified. Vulnerable populations, especially young children and other persons at high risk for serious influenza complications, should avoid swine barns at agricultural fairs, or close contact with swine.§.


Asunto(s)
Brotes de Enfermedades , Salud Global/estadística & datos numéricos , Gripe Humana/epidemiología , Vigilancia de la Población , Farmacorresistencia Viral , Humanos , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H1N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N2 del Virus de la Influenza A/genética , Subtipo H1N2 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Virus de la Influenza B/aislamiento & purificación , Vacunas contra la Influenza/química , Gripe Humana/virología , Estaciones del Año , Estados Unidos/epidemiología
11.
MMWR Morb Mortal Wkly Rep ; 67(22): 634-642, 2018 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-29879098

RESUMEN

The United States 2017-18 influenza season (October 1, 2017-May 19, 2018) was a high severity season with high levels of outpatient clinic and emergency department visits for influenza-like illness (ILI), high influenza-related hospitalization rates, and elevated and geographically widespread influenza activity across the country for an extended period. Nationally, ILI activity began increasing in November, reaching an extended period of high activity during January-February, and remaining elevated through March. Influenza A(H3N2) viruses predominated through February and were predominant overall for the season; influenza B viruses predominated from March onward. This report summarizes U.S. influenza activity* during October 1, 2017-May 19, 2018.†.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Niño , Mortalidad del Niño , Preescolar , Farmacorresistencia Viral , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Mortalidad Infantil , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Vacunas contra la Influenza/química , Gripe Humana/mortalidad , Gripe Humana/prevención & control , Gripe Humana/virología , Persona de Mediana Edad , Pacientes Ambulatorios/estadística & datos numéricos , Neumonía/mortalidad , Estaciones del Año , Índice de Severidad de la Enfermedad , Estados Unidos/epidemiología , Adulto Joven
12.
Emerg Infect Dis ; 24(7)2018 07.
Artículo en Inglés | MEDLINE | ID: mdl-29715078

RESUMEN

Influenza virologic surveillance is critical each season for tracking influenza circulation, following trends in antiviral drug resistance, detecting novel influenza infections in humans, and selecting viruses for use in annual seasonal vaccine production. We developed a framework and process map for characterizing the landscape of US influenza virologic surveillance into 5 tiers of influenza testing: outpatient settings (tier 1), inpatient settings and commercial laboratories (tier 2), state public health laboratories (tier 3), National Influenza Reference Center laboratories (tier 4), and Centers for Disease Control and Prevention laboratories (tier 5). During the 2015-16 season, the numbers of influenza tests directly contributing to virologic surveillance were 804,000 in tiers 1 and 2; 78,000 in tier 3; 2,800 in tier 4; and 3,400 in tier 5. With the release of the 2017 US Pandemic Influenza Plan, the proposed framework will support public health officials in modeling, surveillance, and pandemic planning and response.


Asunto(s)
Virus de la Influenza A , Virus de la Influenza B , Gripe Humana/epidemiología , Gripe Humana/virología , Humanos , Vigilancia de la Población , Prevalencia , Estados Unidos/epidemiología
13.
MMWR Morb Mortal Wkly Rep ; 67(6): 169-179, 2018 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-29447145

RESUMEN

Influenza activity in the United States began to increase in early November 2017 and rose sharply from December through February 3, 2018; elevated influenza activity is expected to continue for several more weeks. Influenza A viruses have been most commonly identified, with influenza A(H3N2) viruses predominating, but influenza A(H1N1)pdm09 and influenza B viruses were also reported. This report summarizes U.S. influenza activity* during October 1, 2017-February 3, 2018,† and updates the previous summary (1).


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Atención Ambulatoria/estadística & datos numéricos , Antivirales/farmacología , Niño , Mortalidad del Niño , Preescolar , Farmacorresistencia Viral , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Gripe Humana/mortalidad , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Neumonía/mortalidad , Embarazo , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
14.
Pediatrics ; 141(4)2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29440502

RESUMEN

BACKGROUND: Influenza-associated pediatric deaths became a notifiable condition in the United States in 2004. METHODS: We analyzed deaths in children aged <18 years with laboratory-confirmed influenza virus infection reported to the Centers for Disease Control and Prevention during the 2010-2011 to 2015-2016 influenza seasons. Data were collected with a standard case report form that included demographics, medical conditions, and clinical diagnoses. RESULTS: Overall, 675 deaths were reported. The median age was 6 years (interquartile range: 2-12). The average annual incidence was 0.15 per 100 000 children (95% confidence interval: 0.14-0.16) and was highest among children aged <6 months (incidence: 0.66; 95% confidence interval: 0.53-0.82), followed by children aged 6-23 months (incidence: 0.33; 95% confidence interval: 0.27-0.39). Only 31% (n = 149 of 477) of children aged ≥6 months had received any influenza vaccination. Overall, 65% (n = 410 of 628) of children died within 7 days after symptom onset. Half of the children (n = 327 of 654) had no preexisting medical conditions. Compared with children with preexisting medical conditions, children with none were younger (median: 5 vs 8 years old), less vaccinated (27% vs 36%), more likely to die before hospital admission (77% vs 48%), and had a shorter illness duration (4 vs 7 days; P < .05 for all). CONCLUSIONS: Each year, influenza-associated pediatric deaths are reported. Young children have the highest death rates, especially infants aged <6 months. Increasing vaccination among children, pregnant women, and caregivers of infants may reduce influenza-associated pediatric deaths.


Asunto(s)
Virus de la Influenza A , Virus de la Influenza B , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/mortalidad , Gripe Humana/prevención & control , Mortalidad/tendencias , Adolescente , Niño , Preescolar , Humanos , Lactante , Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/diagnóstico , Estados Unidos/epidemiología
15.
Influenza Other Respir Viruses ; 12(1): 132-137, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29446233

RESUMEN

BACKGROUND: Estimates of influenza disease burden are broadly useful for public health, helping national and local authorities monitor epidemiologic trends, plan and allocate resources, and promote influenza vaccination. Historically, estimates of the burden of seasonal influenza in the United States, focused mainly on influenza-related mortality and hospitalization, were generated every few years. Since the 2010-2011 influenza season, annual US influenza burden estimates have been generated and expanded to include estimates of influenza-related outpatient medical visits and symptomatic illness in the community. METHODS: We used routinely collected surveillance data, outbreak field investigations, and proportions of people seeking health care from survey results to estimate the number of illnesses, medical visits, hospitalizations, and deaths due to influenza during six influenza seasons (2010-2011 through 2015-2016). RESULTS: We estimate that the number of influenza-related illnesses that have occurred during influenza season has ranged from 9.2 million to 35.6 million, including 140 000 to 710 000 influenza-related hospitalizations. DISCUSSION: These annual efforts have strengthened public health communications products and supported timely assessment of the impact of vaccination through estimates of illness and hospitalizations averted. Additionally, annual estimates of influenza burden have highlighted areas where disease surveillance needs improvement to better support public health decision making for seasonal influenza epidemics as well as future pandemics.


Asunto(s)
Gripe Humana/epidemiología , Gripe Humana/prevención & control , Vigilancia de la Población/métodos , Adolescente , Adulto , Anciano , Niño , Preescolar , Costo de Enfermedad , Humanos , Lactante , Vacunas contra la Influenza/administración & dosificación , Vacunas contra la Influenza/inmunología , Persona de Mediana Edad , Estudios Retrospectivos , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
16.
Am J Epidemiol ; 187(5): 1040-1050, 2018 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-29053783

RESUMEN

Assessments of influenza season severity can guide public health action. We used the moving epidemic method to develop intensity thresholds (ITs) for 3 US surveillance indicators from the 2003-2004 through 2014-2015 influenza seasons (excluding the 2009 pandemic). The indicators were: 1) outpatient visits for influenza-like illness; 2) influenza-related hospitalizations; and 3) influenza- and pneumonia-related deaths. ITs were developed for the population overall and separately for children, adults, and older adults, and they were set at the upper limit of the 50% (IT50), 90% (IT90), and 98% (IT98) 1-sided confidence intervals of the geometric mean of each season's 3 highest values. Severity was classified as low if ≥2 systems peaked below IT50, moderate if ≥2 peaked between IT50 and IT90, high if ≥2 peaked between IT90 and IT98, and very high if ≥2 peaked above IT98. We pilot-tested this method with the 2015-2016 season and the 2009 pandemic. Overall, 4 seasons were classified as low severity, 7 as moderate, 2 as high, and none as very high. Among the age groups, older adults had the most seasons (n = 3) classified as high, and children were the only group to have seasons (n = 2) classified as very high. We will apply this method to classify the severity of future seasons and inform pandemic response.


Asunto(s)
Métodos Epidemiológicos , Gripe Humana/epidemiología , Pandemias/clasificación , Adolescente , Adulto , Anciano , Niño , Preescolar , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Persona de Mediana Edad , Estados Unidos/epidemiología , Adulto Joven
17.
MMWR Morb Mortal Wkly Rep ; 66(48): 1318-1326, 2017 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-29216030

RESUMEN

Influenza activity in the United States was low during October 2017, but has been increasing since the beginning of November. Influenza A viruses have been most commonly identified, with influenza A(H3N2) viruses predominating. Several influenza activity indicators were higher than is typically seen for this time of year. The majority of influenza viruses characterized during this period were genetically or antigenically similar to the 2017-18 Northern Hemisphere cell-grown vaccine reference viruses. These data indicate that currently circulating viruses have not undergone significant antigenic drift; however, circulating A(H3N2) viruses are antigenically less similar to egg-grown A(H3N2) viruses used for producing the majority of influenza vaccines in the United States. It is difficult to predict which influenza viruses will predominate in the 2017-18 influenza season; however, in recent past seasons in which A(H3N2) viruses predominated, hospitalizations and deaths were more common, and the effectiveness of the vaccine was lower. Annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. Multiple influenza vaccines are approved and recommended for use during the 2017-18 season, and vaccination should continue to be offered as long as influenza viruses are circulating and unexpired vaccine is available. This report summarizes U.S. influenza activity* during October 1-November 25, 2017 (surveillance weeks 40-47).†.


Asunto(s)
Brotes de Enfermedades , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H1N2 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Niño , Mortalidad del Niño , Preescolar , Farmacorresistencia Viral , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Gripe Humana/mortalidad , Gripe Humana/virología , Persona de Mediana Edad , Pacientes Ambulatorios/estadística & datos numéricos , Neumonía/epidemiología , Neumonía/mortalidad , Estados Unidos/epidemiología , Adulto Joven
18.
MMWR Morb Mortal Wkly Rep ; 66(39): 1043-1051, 2017 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-28981486

RESUMEN

During May 21-September 23, 2017,* the United States experienced low-level seasonal influenza virus activity; however, beginning in early September, CDC received reports of a small number of localized influenza outbreaks caused by influenza A(H3N2) viruses. In addition to influenza A(H3N2) viruses, influenza A(H1N1)pdm09 and influenza B viruses were detected during May-September worldwide and in the United States. Influenza B viruses predominated in the United States from late May through late June, and influenza A viruses predominated beginning in early July. The majority of the influenza viruses collected and received from the United States and other countries during that time have been characterized genetically or antigenically as being similar to the 2017 Southern Hemisphere and 2017-18 Northern Hemisphere cell-grown vaccine reference viruses; however, a smaller proportion of the circulating A(H3N2) viruses showed similarity to the egg-grown A(H3N2) vaccine reference virus which represents the A(H3N2) viruses used for the majority of vaccine production in the United States. Also, during May 21-September 23, 2017, CDC confirmed a total of 33 influenza variant virus† infections; two were influenza A(H1N2) variant (H1N2v) viruses (Ohio) and 31 were influenza A(H3N2) variant (H3N2v) viruses (Delaware [1], Maryland [13], North Dakota [1], Pennsylvania [1], and Ohio [15]). An additional 18 specimens from Maryland have tested presumptive positive for H3v and further analysis is being conducted at CDC.


Asunto(s)
Brotes de Enfermedades , Salud Global/estadística & datos numéricos , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Humanos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/genética , Estaciones del Año , Estados Unidos/epidemiología
19.
MMWR Morb Mortal Wkly Rep ; 66(25): 668-676, 2017 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-28662019

RESUMEN

During the 2016-17 influenza season (October 2, 2016-May 20, 2017) in the United States, influenza activity* was moderate. Activity remained low through November, increased during December, and peaked in February nationally, although there were regional differences in the timing of influenza activity. Influenza A(H3N2) viruses predominated through mid-March and were predominant overall for the season, but influenza B viruses were most commonly reported from late March through May. This report summarizes influenza activity in the United States during October 2, 2016-May 20, 2017† and updates the previous summary (1).


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H1N2 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Subtipo H7N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Niño , Preescolar , Coinfección , Farmacorresistencia Viral , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Mortalidad Infantil , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H7N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H7N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Vacunas contra la Influenza/química , Gripe Humana/mortalidad , Gripe Humana/prevención & control , Gripe Humana/virología , Persona de Mediana Edad , Pacientes Ambulatorios/estadística & datos numéricos , Neumonía/mortalidad , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
20.
MMWR Morb Mortal Wkly Rep ; 66(6): 159-166, 2017 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-28207684

RESUMEN

This report summarizes U.S. influenza activity* during October 2, 2016-February 4, 2017,† and updates the previous summary (1). Influenza activity in the United States began to increase in mid-December, remained elevated through February 4, 2017, and is expected to continue for several more weeks. To date, influenza A (H3N2) viruses have predominated overall, but influenza A (H1N1)pdm09 and influenza B viruses have also been identified.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H1N2 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Subtipo H7N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de la Población , Adolescente , Adulto , Anciano , Antivirales/farmacología , Niño , Mortalidad del Niño , Preescolar , Farmacorresistencia Viral , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Recién Nacido , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Subtipo H3N2 del Virus de la Influenza A/genética , Virus de la Influenza B/efectos de los fármacos , Virus de la Influenza B/genética , Gripe Humana/mortalidad , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Pacientes Ambulatorios/estadística & datos numéricos , Neumonía/mortalidad , Embarazo , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
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