2016-2017 Influenza Season, Boston Infectious Disease Bureau Boston Public Health Commission
Boston Public Health Commission Influenza Surveillance: Boston, 2016-2017 Influenza cases diagnosed in Boston and confirmed by any laboratory test must be reported to the city health department (Boston Public Health Commission, BPHC).
Boston Public Health Commission Influenza Surveillance: Boston, 2016-2017 BPHC syndromic surveillance data are used to track influenza-like illness (ILI) visits at Emergency Departments (EDs) in Boston. During the season, data are used to inform control measures and provide community situational awareness. Data for this report were analyzed by BPHC after the influenza season.
Number of Reported Cases %ILI ED Visits Boston Public Health Commission Reported Influenza Cases* and Percent of Emergency Department Visits Due to Influenza-Like Illness (ILI)**, Boston, 2016-2017 400 Influenza Cases %ILI ED 3.0% 350 300 250 200 150 100 50 0 2.5% 2.0% 1.5% 1.0% 0.5% 0.0% Note: The 2016-2017 influenza season covers event dates between 10/1/2016-4/30/2017 *Reported cases: Boston residents only. **ED ILI visits: All visits to Boston EDs regardless of residence Week Ending
Number of Reported Cases Boston Public Health Commission Reported Influenza Cases by Influenza Type, Boston Residents, 2016-2017 Influenza A Cases Influenza B Cases 400 350 300 250 200 150 100 50 0 Week Ending Note: The 2016-2017 influenza season covers event dates between 10/1/2016-4/30/2017
% ILI / All Visits Boston Public Health Commission 3.0% Percent of Emergency Department Visits* for Influenza-like Illness (ILI): Boston, 2014-2017** 2014-2015 2015-2016 2016-2017 2.5% 2.0% 1.5% 1.0% 0.5% 0.0% Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug *ED ILI visits: All visits to Boston EDs regardless of residence Month **Predominating influenza A subtypes by season: 2014-15: H3N2 (circulating virus was antigenically drifted from the vaccine strain) 2015-16: H1N1 (circulating virus was well matched to vaccine strain) 2016-17: H3N2 (circulating virus was well matched to vaccine strain)
Boston Public Health Commission Characteristics of Reported Influenza Cases, Boston Residents, 2016-2017 Total Cases N=3285 N (%) Hospitalized 579 (18%) Died (among total cases) 14 (0.4%) Died (among hospitalized cases) 14 (2.4%) N (%) Influenza A * 2383 (73%) Influenza B * 897 (27%) N (%) Male 1380 (42%) Female 1905 (58%) Note: The 2016-2017 influenza season covers event dates between 10/1/2016-4/30/2017 *Excludes five cases who either had both influenza types A and B, or who tested positive with a diagnostic test that does not differentiate between flu types
Age Group (years) Boston Public Health Commission Reported Influenza Cases, Boston Residents*, 2016-2017 Age Age and Gender Female Male 85+ yrs 5% 85+ <5 yrs 10% 64-85 65-84 yrs 16% 5-17 yrs 22% 45-64 yrs 30% 18-44 yrs 17% 45-64 18-44 5-17 < 5 700 600 500 400 300 200 100 0 100 200 300 400 500 600 700 Number of Cases *Boston Population, 2010 Census Data
Age Group (years) Boston Public Health Commission Reported Influenza Cases by Age in Boston Residents, Compared to the Overall Boston Population*, 2016-2017 Boston Population Reported Influenza Cases 85+ 65-84 45-64 18-44 5-17 <5 0% 10% 20% 30% 40% 50% 60% *Boston Population, 2010 Census Data Percent of Total
Race/Ethnicity Boston Public Health Commission Reported Influenza Cases by Race/Ethnicity in Boston Residents, Compared to the Overall Boston Population*, 2016-2017 Boston Population Reported Influenza Cases White Black Latino Asian Other** Unknown 0% 10% 20% 30% 40% 50% 60% Percent of Total *Boston Population, 2010 Census Data **Other is inclusive of American Indian, Alaskan Native, Native Hawaiian, Pacific Islander, and unspecified other race
Boston Public Health Commission Influenza A vs. Influenza B Cases by Race/Ethnicity and Age Group, Boston Residents, 2016-2017 Race/Ethnicity White Black Latino Asian Other* Total Influenza A 72% 73% 74% 71% 71% 73% Influenza B 28% 27% 26% 29% 29% 27% Age Group (years) <5 5-17 18-44 45-64 65-84 85+ Total Influenza A 75% 71% 73% 69% 76% 78% 73% Influenza B 25% 29% 27% 31% 24% 22% 27% *Other is inclusive of American Indian, Alaskan Native, Native Hawaiian, Pacific Islander, and unspecified other race
Boston Public Health Commission Characteristics of Reported Influenza Cases* >64 Years of Age, by Age Range: Boston, 2016-2017 Gender Age Group (years) 65-84 85+ N=514 N=167 Male 41% 39% Female 59% 61% White 43% 51% Black 32% 25% Race Latino 15% 14% Asian 8% 7% Other** 3% 2% Hospitalized 43% 67% Died 1% 4% *Reported cases: Boston Residents only. **Other is inclusive of American Indian, Alaskan Native, Native Hawaiian, Pacific Islander, and unspecified other race
*Data on length of stay, treatment, and co-morbidities missing for 33 of 579 hospitalized cases **LOS=length of stay ***Presented with fall=cases who presented to a hospital as the direct result of a fall, but who were subsequently found to have laboratory-confirmed influenza Boston Public Health Commission Characteristics of Hospitalized* Influenza Cases by Age, Boston Residents, 2016-2017 Age Group (years) <18 18-44 45-64 65-84 85+ All Ages % Cases Hospitalized 3% 5% 21% 43% 67% 18% Median LOS** (days) 3 3 3 3 3 3 Oseltamivir treatment 86% 88% 90% 95% 95% 92% Asthma 45% 26% 30% 26% 27% 28% Cardiac Disease 62% 10% 35% 59% 49% 52% Chronic Obstructive Pulmonary Disease 41% 28% 16% 24% 21% 23% Diabetes 50% 30% 33% 36% 37% 35% Pneumonia 28% 22% 24% 31% 31% 28% Presented with fall*** 3% 8% 9% 8% 14% 9%
*Data on length of stay, treatment, and co-morbidities missing for 33 of 579 hospitalized cases **LOS=length of stay ***Presented with fall=cases who presented to a hospital as the direct result of a fall, but who were subsequently found to have laboratory-confirmed influenza Boston Public Health Commission Characteristics of Hospitalized* Influenza Cases by Race/Ethnicity, Boston Residents, 2016-2017 Reported Race/Ethnicity White Black Latino Asian Total % Cases Hospitalized 22% 19% 14% 15% 18% Median LOS** (days) 4 3 3 3 3 Oseltamivir treatment 88% 95% 98% 93% 92% Asthma 22% 27% 45% 15% 28% Cardiac Disease 55% 45% 45% 41% 48% Chronic Obstructive Pulmonary Disease 32% 16% 19% 15% 23% Diabetes 32% 38% 38% 33% 35% Pneumonia 34% 24% 29% 19% 28% Presented with fall*** 11% 9% 7% 11% 9%
Boston Public Health Commission Characteristics of Hospitalized* Influenza Cases by Influenza Type, Boston Residents, 2016-2017 Influenza A Influenza B % Cases Hospitalized** 18% 16% # of Deaths 14 0 Median LOS*** (days) 3 3 Oseltamivir treatment 93% 91% Asthma 30% 21% Cardiac Disease 49% 44% Chronic Obstructive Pulmonary Disease 24% 19% Diabetes 35% 36% Pneumonia 28% 29% Presented with fall**** 9% 7% *Data on length of stay, treatment, and co-morbidities missing for 33 of 579 hospitalized cases **Each percentage indicates the proportion of all cases with the corresponding influenza type (A or B) who were hospitalized ***LOS=length of stay ****Presented with fall=cases who presented to a hospital as the direct result of a fall, but who were subsequently found to have laboratory-confirmed influenza
Boston Public Health Commission Characteristics of Hospitalized* Influenza Cases >64 Years of Age, by Age Range: Boston, 2016-2017 Age Group (years) 65-84 85+ % Hospitalized 43% 67% Median LOS** (days) 3 3 Oseltamivir treatment 95% 95% Asthma 26% 27% Cardiac Disease 51% 51% Chronic Obstructive Pulmonary Disease 24% 21% Diabetes 36% 37% Pneumonia 31% 31% Presented with Fall*** 8% 14% *Data on length of stay, treatment, and co-morbidities missing for 33 of 579 hospitalized cases **LOS=length of stay ***Presented with fall=cases who presented to a hospital as the direct result of a fall, but who were subsequently found to have laboratory-confirmed influenza
Boston Public Health Commission Confirmed Influenza Cases and ILI Emergency Department (ED) Visits in Boston Residents, 2016-2017 Confirmed Influenza Cases, per 100,000 population, 10/1/2016-4/30/2017 ILI ED Visits, per 100,000 population, 10/1/2016-4/30/2017 Neighborhood Legend A/B=Allston/Brighton BB=Back Bay CH=Charlestown EB=East Boston FW=Fenway HP=Hyde Park JP=Jamaica Plain MT=Mattapan ND=North Dorchester RS=Roslindale RX=Roxbury SB=South Boston SD=South Dorchester SE=South End WR=West Roxbury
Metro Boston FNY % ILI % ILI Visits (Boston Hospitals) Boston Public Health Commission Comparison of ILI Using Flu Near You (FNY)** and Boston Emergency Department (ED) Syndromic* Data, 2015-2017 12 Metro Boston FNY % ILI % ILI ED Visits (Boston Hospitals) 3.0 10 2.5 8 2.0 6 1.5 4 1.0 2 0.5 0 0.0 Week Ending *All visits to Boston EDs regardless of residence **Flu Near You (FNY) compiles weekly data of ILI activity in the United States. The data come from short, weekly internet-based surveys completed by voluntary participants who indicate whether they are healthy or have experienced any of a short list of symptoms. The public may participate by enrolling in FNY at: https://flunearyou.org/
Boston Public Health Commission Influenza in Boston: 2016-2017 18% of reported cases were hospitalized. Despite current guidelines, not all hospitalized influenza cases were treated with an antiviral medication.
Boston Public Health Commission Influenza in Boston: 2016-2017 9% of hospitalized influenza cases sought healthcare due to a fall, not influenza. The elderly were more likely to present due to a fall, most often associated with concomitant dehydration due to influenza infection Information from a community participatory disease surveillance system correlated well with data from case reporting and syndromic surveillance.
Infectious Disease Bureau P: (617) 534-5611 F: (617) 534-5905 www.bphc.org/cdc