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1.
Clin Infect Dis ; 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32006430

RESUMEN

BACKGROUND: Since 2013, quadrivalent influenza vaccines containing two B viruses gradually replaced trivalent vaccines in the United States. We compared vaccine effectiveness of quadrivalent to trivalent inactivated vaccines (IIV4 to IIV3) against illness due to influenza B during the transition when IIV4 use increased rapidly. METHODS: The US Influenza Vaccine Effectiveness (Flu VE) Network analyzed 25,019 of 42,600 outpatients aged ≥6 months enrolled within 7 days of illness-onset during six seasons from 2011-2012. Upper respiratory specimens were tested for influenza virus type and B-lineage. Using logistic regression, we estimated IIV4 or IIV3 effectiveness by comparing the odds of influenza B infection overall, and by B lineage among vaccinated versus unvaccinated participants. Over four seasons from 2013-2014, we compared relative odds of influenza B infection among IIV4 versus IIV3 recipients. RESULTS: Trivalent vaccines included the predominantly circulating B lineage in four of six seasons. During four influenza seasons when both IIV4 and IIV3 were widely used, overall effectiveness against any influenza B was 53% (95% confidence interval [CI], 45 to 59) for IIV4 versus 45% (95% CI, 34 to 54) for IIV3. IIV4 was more effective than IIV3 against the B lineage not included in IIV3, but comparative effectiveness against illness related to any influenza B favored neither vaccine valency. CONCLUSIONS: Uptake of quadrivalent inactivated influenza vaccines was not associated with increased protection against any influenza B illness, despite higher effectiveness of quadrivalent vaccines against the added B virus lineage. Public health impact and cost-benefit analyses are needed globally.

2.
MMWR Morb Mortal Wkly Rep ; 69(6): 166-170, 2020 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-32053579

RESUMEN

In December 2019, a cluster of cases of pneumonia emerged in Wuhan City in central China's Hubei Province. Genetic sequencing of isolates obtained from patients with pneumonia identified a novel coronavirus (2019-nCoV) as the etiology (1). As of February 4, 2020, approximately 20,000 confirmed cases had been identified in China and an additional 159 confirmed cases in 23 other countries, including 11 in the United States (2,3). On January 17, CDC and the U.S. Department of Homeland Security's Customs and Border Protection began health screenings at U.S. airports to identify ill travelers returning from Wuhan City (4). CDC activated its Emergency Operations Center on January 21 and formalized a process for inquiries regarding persons suspected of having 2019-nCoV infection (2). As of January 31, 2020, CDC had responded to clinical inquiries from public health officials and health care providers to assist in evaluating approximately 650 persons thought to be at risk for 2019-nCoV infection. Guided by CDC criteria for the evaluation of persons under investigation (PUIs) (5), 210 symptomatic persons were tested for 2019-nCoV; among these persons, 148 (70%) had travel-related risk only, 42 (20%) had close contact with an ill laboratory-confirmed 2019-nCoV patient or PUI, and 18 (9%) had both travel- and contact-related risks. Eleven of these persons had laboratory-confirmed 2019-nCoV infection. Recognizing persons at risk for 2019-nCoV is critical to identifying cases and preventing further transmission. Health care providers should remain vigilant and adhere to recommended infection prevention and control practices when evaluating patients for possible 2019-nCoV infection (6). Providers should consult with their local and state health departments when assessing not only ill travelers from 2019-nCoV-affected countries but also ill persons who have been in close contact with patients with laboratory-confirmed 2019-nCoV infection in the United States.


Asunto(s)
Betacoronavirus/aislamiento & purificación , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/virología , Brotes de Enfermedades/prevención & control , Tamizaje Masivo/estadística & datos numéricos , Adolescente , Adulto , Anciano , Niño , Preescolar , Trazado de Contacto , Infecciones por Coronavirus/prevención & control , Femenino , Humanos , Masculino , Persona de Mediana Edad , Medición de Riesgo , Enfermedad Relacionada con los Viajes , Estados Unidos/epidemiología , Adulto Joven
3.
MMWR Morb Mortal Wkly Rep ; 69(7): 177-182, 2020 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-32078591

RESUMEN

During the 2019-20 influenza season, influenza-like illness (ILI)* activity first exceeded the national baseline during the week ending November 9, 2019, signaling the earliest start to the influenza season since the 2009 influenza A(H1N1) pandemic. Activity remains elevated as of mid-February 2020. In the United States, annual vaccination against seasonal influenza is recommended for all persons aged ≥6 months (1). During each influenza season, CDC estimates seasonal influenza vaccine effectiveness in preventing laboratory-confirmed influenza associated with medically attended acute respiratory illness (ARI). This interim report used data from 4,112 children and adults enrolled in the U.S. Influenza Vaccine Effectiveness Network (U.S. Flu VE Network) during October 23, 2019-January 25, 2020. Overall, vaccine effectiveness (VE) against any influenza virus associated with medically attended ARI was 45% (95% confidence interval [CI] = 36%-53%). VE was estimated to be 50% (95% CI = 39%-59%) against influenza B/Victoria viruses and 37% (95% CI = 19%-52%) against influenza A(H1N1)pdm09, indicating that vaccine has significantly reduced medical visits associated with influenza so far this season. Notably, vaccination provided substantial protection (VE = 55%; 95% CI = 42%-65%) among children and adolescents aged 6 months-17 years. Interim VE estimates are consistent with those from previous seasons, ranging from 40%-60% when influenza vaccines were antigenically matched to circulating viruses. CDC recommends that health care providers continue to administer influenza vaccine to persons aged ≥6 months because influenza activity is ongoing, and the vaccine can still prevent illness, hospitalization, and death associated with currently circulating influenza viruses as well as other influenza viruses that might circulate later in the season.


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 , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Vigilancia de la Población , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Humanos , Lactante , Vacunas contra la Influenza/inmunología , Gripe Humana/epidemiología , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
4.
Clin Infect Dis ; 2020 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-31960898
5.
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
7.
Clin Infect Dis ; 2020 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-31905401

RESUMEN

BACKGROUND: Current multivalent influenza vaccine products provide protection against influenza A(H1N1)pdm09, A(H3N2), and B lineage viruses. The 2018-2019 influenza season in the US included prolonged circulation of both A(H1N1)pdm09 viruses well-matched to the vaccine strain, and A(H3N2) viruses the majority of which were mismatched to the vaccine. We estimate the number of vaccine-prevented influenza-associated illnesses, medical visits, hospitalizations, and deaths for the season. METHODS: We used a mathematical model and Monte Carlo algorithm to estimate numbers and 95% uncertainty intervals (UI) of influenza-associated outcomes prevented by vaccination in the US. The model incorporated age-specific estimates of national 2018-2019 influenza vaccine coverage, influenza virus-specific vaccine effectiveness from the US Influenza Vaccine Effectiveness Network, and disease burden estimated from population-based rates of influenza-associated hospitalizations through the Influenza Hospitalization Surveillance Network. RESULTS: Influenza vaccination prevented an estimated 4.4 million (95% UI: 3.4 million-7.1 million) illnesses, 2.3 million (95% UI: 1.8 million-3.8 million) medical visits, 58,000 (95% UI: 30,000-156,000) hospitalizations, and 3,500 (95% UI: 1,000-13,000) deaths due to influenza viruses during the US 2018-2019 influenza season. Vaccination prevented 14% of projected hospitalizations associated with A(H1N1)pdm09 overall and 43% among young children aged 6 months-4 years. CONCLUSIONS: Influenza vaccination averted substantial influenza-associated disease including hospitalizations and deaths in the US, primarily due to effectiveness against A(H1N1)pdm09. Our findings underscore the value of influenza vaccination, highlighting that vaccines measurably decrease illness and associated health care utilization even in a season in which a vaccine component does not match to a circulating virus.

8.
Vaccine ; 38(3): 608-619, 2020 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-31735505

RESUMEN

BACKGROUND: Identifying optimal priming strategies for children <2 years could substantially improve the public health benefits of influenza vaccines. Adjuvanted seasonal influenza vaccines were designed to promote a better immune response among young vaccine-naïve children. METHODS: We systematically reviewed randomized trials to assess hemagglutination inhibition (HAI) antibody response to MF59-adjuvanted inactivated influenza vaccine (aIIV) versus nonadjuvanted IIV among children. We estimated pooled ratios of post-vaccination HAI geometric mean titer (GMT) for aIIV versus IIV and confidence intervals (CIs) using the pooled variances derived from reported CIs. RESULTS: Mean age was 28 months (range, 6-72 months). Children received vaccines with either 7.5 µg (6-35 months) or 15 µg (≥36 months) hemagglutinin of each strain depending on age. Seven of eight trials administered trivalent vaccines and one used quadrivalent vaccine. Pooled post-vaccination GMT ratios against the three influenza vaccine strains were 2.5-3.5 fold higher after 2-dose-aIIV versus 2-dose-IIV among children 6-72 months, and point estimates were higher among children 6-35 months compared with older children. When comparing 1-dose-aIIV to 2-dose-IIV doses, pooled GMT ratios were not significantly different against A/H1N1 (1.0; 95% CI: 0.5-1.8; p = 0.90) and A/H3N2 viruses (1.0; 95% CI: 0.7-1.5; p = 0.81) and were significantly lower against B viruses (0.6; 95% CI: 0.4-0.8; p < 0.001) for both age groups. Notably, GMT ratios for vaccine-mismatched heterologous viruses after 2-dose-aIIV compared with 2-dose-IIV were higher against A/H1N1 (2.0; 95% CI: 1.1-3.4), A/H3N2 (2.9; 95% CI: 1.9-4.2), and B-lineage viruses (2.1; 95% CI: 1.8-2.6). CONCLUSIONS: Two doses of adjuvanted IIV consistently induced better humoral immune responses against Type A and B influenza viruses compared with nonadjuvanted IIVs in young children, particularly among those 6-35 months. One adjuvanted IIV dose had a similar response to two nonadjuvanted IIV doses against Type A influenza viruses. Longer-term benefits from imprinting and cell-mediated immunity, including trials of clinical efficacy, are gaps that warrant investigation.

9.
Clin Infect Dis ; 70(2): 357-358, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31112216
10.
11.
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.

12.
Clin Infect Dis ; 2019 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-31828291

RESUMEN

BACKGROUND: Enhanced influenza vaccines may improve protection for older adults, but comparative immunogenicity data are limited. Our objective was to examine immune responses to enhanced influenza vaccines, compared to standard-dose vaccines, in community-dwelling older adults. METHODS: Community-dwelling older adults aged 65-82 years in Hong Kong were randomly allocated (October 2017-January 2018) to receive 2017-2018 Northern hemisphere formulations of a standard-dose quadrivalent vaccine, MF59-adjuvanted trivalent vaccine, high-dose trivalent vaccine, or recombinant-hemagglutinin (rHA) quadrivalent vaccine. Sera collected from 200 recipients of each vaccine before and at 30-days postvaccination were assessed for antibodies to egg-propagated vaccine strains by hemagglutination inhibition (HAI) and to cell-propagated A/Hong Kong/4801/2014(H3N2) virus by microneutralization (MN). Influenza-specific CD4+ and CD8+ T cell responses were assessed in 20 participants per group. RESULTS: Mean fold rises (MFR) in HAI titers to egg-propagated A(H1N1) and A(H3N2) and the MFR in MN to cell-propagated A(H3N2) were statistically significantly higher in the enhanced vaccine groups, compared to the standard-dose vaccine. The MFR in MN to cell-propagated A(H3N2) was highest among rHA recipients (4.7), followed by high-dose (3.4) and MF59-adjuvanted (2.9) recipients, compared to standard-dose recipients (2.3). Similarly, the ratio of postvaccination MN titers among rHA recipients to cell-propagated A(H3N2) recipients was 2.57-fold higher than the standard-dose vaccine, which was statistically higher than the high-dose (1.33-fold) and MF59-adjuvanted (1.43-fold) recipient ratios. Enhanced vaccines also resulted in the boosting of T-cell responses. CONCLUSIONS: In this head-to-head comparison, older adults receiving enhanced vaccines showed improved humoral and cell-mediated immune responses, compared to standard-dose vaccine recipients. CLINICAL TRIALS REGISTRATION: NCT03330132.

13.
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
14.
Vaccine X ; 1: 100008, 2019 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-31384730

RESUMEN

Background: Vaccination history may confound estimates of influenza vaccine effectiveness (VE) when two conditions are present: (1) Influenza vaccination is associated with vaccination history and (2) vaccination modifies the risk of natural infection in the following seasons, either due to persisting vaccination immunity or due to lower previous risk of natural infection. Methods: Analytic arguments are used to define conditions for confounding of VE estimates by vaccination history. Simulation studies, both with accurate and inaccurate assessment of current and previous vaccination status, are used to explore the potential magnitude of these biases when using different statistical models to address confounding by vaccination history. Results: We found a potential for substantial bias of VE estimates by vaccination history if infection- and/or vaccination-derived immunity persisted from one season to the next and if vaccination uptake in individuals was seasonally correlated. Full adjustment by vaccination history, which is usually not feasible, resulted in unbiased VE estimates. Partial adjustment, i.e. only by prior season's vaccination status, significantly reduced confounding bias. Misclassification of vaccination status, which can also lead to substantial bias, interferes with the adjustment of VE estimates for vaccination history. Conclusions: Confounding by vaccination history may bias VE estimates, but even partial adjustment by only the prior season's vaccination status substantially reduces confounding bias. Misclassification of vaccination status may compromise VE estimates and efforts to adjust for vaccination history.

15.
MMWR Recomm Rep ; 68(3): 1-21, 2019 08 23.
Artículo en Inglés | MEDLINE | ID: mdl-31441906

RESUMEN

This report updates the 2018-19 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2018;67[No. RR-3]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. A licensed, recommended, and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV), and live attenuated influenza vaccine (LAIV) are expected to be available for the 2019-20 season. Standard-dose, unadjuvanted, inactivated influenza vaccines will be available in quadrivalent formulations (IIV4s). High-dose (HD-IIV3) and adjuvanted (aIIV3) inactivated influenza vaccines will be available in trivalent formulations. Recombinant (RIV4) and live attenuated influenza vaccine (LAIV4) will be available in quadrivalent formulations.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 25, 2018; February 27, 2019; and June 27, 2019. Primary updates in this report include the following two items. First, 2019-20 U.S. trivalent influenza vaccines will contain hemagglutinin (HA) derived from an A/Brisbane/02/2018 (H1N1)pdm09-like virus, an A/Kansas/14/2017 (H3N2)-like virus, and a B/Colorado/06/2017-like virus (Victoria lineage). Quadrivalent influenza vaccines will contain HA derived from these three viruses, and a B/Phuket/3073/2013-like virus (Yamagata lineage). Second, recent labeling changes for two IIV4s, Afluria Quadrivalent and Fluzone Quadrivalent, are discussed. The age indication for Afluria Quadrivalent has been expanded from ≥5 years to ≥6 months. The dose volume for Afluria Quadrivalent is 0.25 mL for children aged 6 through 35 months and 0.5 mL for all persons aged ≥36 months (≥3 years). The dose volume for Fluzone Quadrivalent for children aged 6 through 35 months, which was previously 0.25 mL, is now either 0.25 mL or 0.5 mL. The dose volume for Fluzone Quadrivalent is 0.5 mL for all persons aged ≥36 months (≥3 years).This report focuses on the recommendations for use of vaccines for the prevention and control of influenza during the 2019-20 season in the United States. A brief summary of these recommendations and a Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information.


Asunto(s)
Vacunas contra la Influenza/uso terapéutico , Gripe Humana/prevención & control , Adolescente , Adulto , Comités Consultivos , Anciano , Niño , Preescolar , Femenino , Humanos , Esquemas de Inmunización , Lactante , Vacunas contra la Influenza/efectos adversos , Gripe Humana/epidemiología , Masculino , Persona de Mediana Edad , Embarazo , Ensayos Clínicos Controlados Aleatorios como Asunto , Medición de Riesgo , Estaciones del Año , Estados Unidos/epidemiología , Adulto Joven
16.
Clin Infect Dis ; 2019 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-31344229

RESUMEN

BACKGROUND: Vaccination is the best way to prevent influenza; however, greater benefit could be achieved. To help guide research and policy agendas, we aimed to quantify the magnitude of influenza disease that would be prevented through targeted increases in vaccine effectiveness (VE) or coverage. METHODS: For three influenza seasons (2011-12, 2015-16, and 2017-18) we used a mathematical model to estimate the number of prevented influenza-associated illnesses, medically-attended illnesses, and hospitalizations across five age groups. Compared with estimates of prevented illness during each season, given observed VE and coverage, we explored the number of additional outcomes that would be prevented from a 5% absolute increase in VE or coverage or achieving 60% VE or 70% coverage. RESULTS: During the 2017-18 season, compared with the burden already prevented by influenza vaccination, a 5% absolute VE increase would prevent an additional 1,050,000 illnesses and 25,000 hospitalizations (76% among those aged ≥65 years) while achieving 60% VE would prevent an additional 190,000 hospitalizations. A 5% coverage increase would result in 785,000 fewer illnesses (56% among those aged 18-64 years) and 11,000 fewer hospitalizations; reaching 70% would prevent an additional 39,000 hospitalizations. CONCLUSIONS: Small, attainable improvements in effectiveness or coverage of influenza vaccine could lead to substantial additional reductions in influenza burden in the U.S. Improvements in VE would have the greatest impact in reducing hospitalizations in adults aged ≥65 years and coverage improvements would have the largest benefit in reducing illnesses in adults aged 18-49 years.

17.
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
18.
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.

20.
JMIR Public Health Surveill ; 5(2): e10842, 2019 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-31025948

RESUMEN

BACKGROUND: Rapid reporting of human infections with novel influenza A viruses accelerates detection of viruses with pandemic potential and implementation of an effective public health response. After detection of human infections with influenza A (H3N2) variant (H3N2v) viruses associated with agricultural fairs during August 2016, the Michigan Department of Health and Human Services worked with the US Centers for Disease Control and Prevention (CDC) to identify infections with variant influenza viruses using a text-based illness monitoring system. OBJECTIVE: To enhance detection of influenza infections using text-based monitoring and evaluate the feasibility and acceptability of the system for use in future outbreaks of novel influenza viruses. METHODS: During an outbreak of H3N2v virus infections among agricultural fair attendees, we deployed a text-illness monitoring (TIM) system to conduct active illness surveillance among households of youth who exhibited swine at fairs. We selected all fairs with suspected H3N2v virus infections. For fairs without suspected infections, we selected only those fairs that met predefined criteria. Eligible respondents were identified and recruited through email outreach and/or on-site meetings at fairs. During the fairs and for 10 days after selected fairs, enrolled households received daily, automated text-messages inquiring about illness; reports of illness were investigated by local health departments. To understand the feasibility and acceptability of the system, we monitored enrollment and trends in participation and distributed a Web-based survey to households of exhibitors from five fairs. RESULTS: Among an estimated 500 households with a member who exhibited swine at one of nine selected fairs, representatives of 87 (17.4%) households were enrolled, representing 392 household members. Among fairs that were ongoing when the TIM system was deployed, the number of respondents peaked at 54 on the third day of the fair and then steadily declined throughout the rest of the monitoring period; 19 out of 87 household representatives (22%) responded through the end of the 10-day monitoring period. We detected 2 H3N2v virus infections using the TIM system, which represents 17% (2/12) of all H3N2v virus infections detected during this outbreak in Michigan. Of the 70 survey respondents, 16 (23%) had participated in the TIM system. A total of 73% (11/15) participated because it was recommended by fair coordinators and 80% (12/15) said they would participate again. CONCLUSIONS: Using a text-message system, we monitored for illness among a large number of individuals and households and detected H3N2v virus infections through active surveillance. Text-based illness monitoring systems are useful for detecting novel influenza virus infections when active monitoring is necessary. Participant retention and testing of persons reporting illness are critical elements for system improvement.

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