ABSTRACT
CDC collects, compiles, and analyzes data on influenza activity year-round in the United States. The influenza season generally begins in the fall and continues through the winter and spring months; however, the timing and severity of circulating influenza viruses can vary by geographic location and season. Influenza activity in the United States remained low through October and November in 2015. Influenza A viruses have been most frequently identified, with influenza A (H3) viruses predominating. This report summarizes U.S. influenza activity for the period October 4-November 28, 2015.
Subject(s)
Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza B virus/isolation & purification , Influenza, Human/epidemiology , Population Surveillance , Adolescent , Adult , Aged , Ambulatory Care/statistics & numerical data , Antiviral Agents/pharmacology , Child , Child Mortality , Child, Preschool , Drug Resistance, Viral , Humans , Infant , Infant, Newborn , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H3N2 Subtype/drug effects , Influenza B virus/drug effects , Influenza, Human/complications , Influenza, Human/mortality , Influenza, Human/virology , Middle Aged , Pneumonia/complications , Pneumonia/mortality , Seasons , United States/epidemiology , Young AdultABSTRACT
During May 24September 5, 2015, the United States experienced typical low levels of seasonal influenza activity. Influenza A (H1N1)pdm09 (pH1N1), influenza A (H3N2), and influenza B viruses were detected worldwide and were identified sporadically in the United States. All of the influenza viruses collected from U.S. states and other countries during that time have been characterized antigenically and/or genetically as being similar to the influenza vaccine viruses recommended for inclusion in the 201516 Northern Hemisphere vaccine. During May 24September 5, 2015, three influenza variant virus infections were reported; one influenza A (H3N2) variant virus (H3N2v) from Minnesota in July, one influenza A (H1N1) variant (H1N1v) from Iowa in August, and one H3N2v from Michigan in August.
Subject(s)
Global Health/statistics & numerical data , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza B virus/isolation & purification , Influenza, Human/epidemiology , Population Surveillance , Humans , Influenza A Virus, H1N1 Subtype/genetics , Influenza A Virus, H3N2 Subtype/genetics , Influenza B virus/genetics , Seasons , United States/epidemiologyABSTRACT
During the 2014-15 influenza season in the United States, influenza activity increased through late November and December before peaking in late December. Influenza A (H3N2) viruses predominated, and the prevalence of influenza B viruses increased late in the season. This influenza season, similar to previous influenza A (H3N2)-predominant seasons, was moderately severe with overall high levels of outpatient illness and influenza-associated hospitalization, especially for adults aged ≥65 years. The majority of circulating influenza A (H3N2) viruses were different from the influenza A (H3N2) component of the 2014-15 Northern Hemisphere seasonal vaccines, and the predominance of these drifted viruses resulted in reduced vaccine effectiveness. This report summarizes influenza activity in the United States during the 2014-15 influenza season (September 28, 2014-May 23, 2015) and reports the recommendations for the components of the 2015-16 Northern Hemisphere influenza vaccine.
Subject(s)
Influenza A virus/isolation & purification , Influenza B virus/isolation & purification , Influenza, Human/epidemiology , Population Surveillance , Adolescent , Adult , Aged , Child , Child Mortality , Child, Preschool , Genetic Variation , Hospitalization/statistics & numerical data , Humans , Infant , Influenza A Virus, H1N1 Subtype/genetics , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/genetics , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza A virus/genetics , Influenza B virus/genetics , Influenza Vaccines/chemistry , Influenza, Human/mortality , Influenza, Human/prevention & control , Influenza, Human/virology , Middle Aged , Outpatients/statistics & numerical data , Pneumonia/mortality , Seasons , United States/epidemiology , Young AdultABSTRACT
Influenza activity in the United States began to increase in mid-November, remained elevated through February 21, 2015, and is expected to continue for several more weeks. To date, influenza A (H3N2) viruses have predominated overall. As has been observed in previous seasons during which influenza A (H3N2) viruses predominated, adults aged ≥65 years have been most severely affected. The cumulative laboratory-confirmed influenza-associated hospitalization rate among adults aged ≥65 years is the highest recorded since this type of surveillance began in 2005. This age group also accounts for the majority of deaths attributed to pneumonia and influenza. The majority of circulating influenza A (H3N2) viruses are different from the influenza A (H3N2) component of the 2014-15 Northern Hemisphere seasonal vaccines, and the predominance of these antigenically and genetically drifted viruses has resulted in reduced vaccine effectiveness. This report summarizes U.S. influenza activity* since September 28, 2014, and updates the previous summary.
Subject(s)
Influenza, Human/chemically induced , Influenza, Human/epidemiology , Adolescent , Adult , Age Distribution , Aged , Cause of Death , Child , Child, Preschool , Comorbidity , Drug Resistance, Viral , Female , Hospitalization/statistics & numerical data , Humans , Infant , Infant Mortality/trends , Influenza A Virus, H1N1 Subtype/genetics , Influenza A Virus, H1N1 Subtype/immunology , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/classification , Influenza A Virus, H3N2 Subtype/genetics , Influenza A Virus, H3N2 Subtype/immunology , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza B virus/classification , Influenza B virus/genetics , Influenza B virus/immunology , Influenza B virus/isolation & purification , Influenza Vaccines , Influenza, Human/prevention & control , Male , Middle Aged , Outpatients/statistics & numerical data , Pneumonia/epidemiology , Population Surveillance , Pregnancy , Seasons , Survival Rate , United States/epidemiology , Young AdultABSTRACT
CDC collects, compiles, and analyzes data on influenza activity year-round in the United States (http://www.cdc.gov/flu/weekly/fluactivitysurv.htm). The influenza season generally begins in the fall and continues through the winter and spring months; however, the timing and severity of circulating influenza viruses can vary by geographic location and season. Influenza activity in the United States increased starting mid-October through December. This report summarizes U.S. influenza activity during September 28-December 6, 2014.
Subject(s)
Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza B virus/isolation & purification , Influenza, Human/epidemiology , Population Surveillance , Humans , Seasons , United States/epidemiologyABSTRACT
During May 18-September 20, 2014, the United States experienced low levels of seasonal influenza activity overall. Influenza A (H1N1)pdm09 (pH1N1), influenza A (H3N2), and influenza B viruses were detected worldwide and were identified sporadically in the United States. In August, two influenza A (H3N2) variant viruses (H3N2v) were detected in Ohio. This report summarizes influenza activity in the United States and worldwide during May 18-September 20, 2014.
Subject(s)
Global Health/statistics & numerical data , Influenza A Virus, H1N1 Subtype , Influenza A Virus, H3N2 Subtype , Influenza B virus , Influenza, Human/epidemiology , Population Surveillance , Humans , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/genetics , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza B virus/isolation & purification , Seasons , United States/epidemiologyABSTRACT
During the 2013-14 influenza season in the United States, influenza activity increased through November and December before peaking in late December. Influenza A (H1N1)pdm09 (pH1N1) viruses predominated overall, but influenza B viruses and, to a lesser extent, influenza A (H3N2) viruses also were reported in the United States. This influenza season was the first since the 2009 pH1N1 pandemic in which pH1N1 viruses predominated and was characterized overall by lower levels of outpatient illness and mortality than influenza A (H3N2)-predominant seasons, but higher rates of hospitalization among adults aged 50-64 years compared with recent years. This report summarizes influenza activity in the United States for the 2013-14 influenza season (September 29, 2013-May 17, 2014) and reports recommendations for the components of the 2014-15 Northern Hemisphere influenza vaccines.
Subject(s)
Influenza A virus/isolation & purification , Influenza B virus/isolation & purification , Influenza, Human/epidemiology , Population Surveillance , Adolescent , Adult , Aged , Child , Child, Preschool , Genetic Variation , Humans , Infant , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/genetics , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza Vaccines/chemistry , Influenza, Human/mortality , Influenza, Human/prevention & control , Influenza, Human/virology , Middle Aged , Outpatients/statistics & numerical data , Pneumonia/mortality , Seasons , United States/epidemiology , Young AdultABSTRACT
Influenza activity in the United States began to increase in mid-November and remained elevated through February 8, 2014. During that time, influenza A (H1N1)pdm09 (pH1N1) viruses predominated overall, while few B and A (H3N2) viruses were detected. This report summarizes U.S. influenza activity* during September 29, 2013-February 8, 2014, and updates the previous summary.
