Cobertura de vacunación contra la influenza, Estados Unidos, temporada de influenza 2019-2020

Resumen

Informe de la página web FluVaxView publicado en línea el 1 de octubre del 2020

To reduce the risk of influenza (flu) illness, hospitalization and death, the Centers for Disease Control and Prevention (CDC) recommends routine annual flu vaccination for all people ≥6 months who do not have contraindications1. CDC analyzed data from two telephone surveys, the National Immunization Survey-Flu (NIS-Flu) and the Behavioral Risk Factor Surveillance System (BRFSS), to estimate flu vaccination coverage for the U.S. population during the 2019-20 flu season. Vaccination coverage with ≥1 dose of flu vaccine was 63,7 % among children 6 months through 17 years, an increase of 1.2 percentage points from the 2018-19 flu season, and flu vaccination coverage among adults ≥18 years was 48,4 %, an increase of 3.1 percentage points from the prior season. Half (51,8 %) of persons six months and older were vaccinated during the 2019-20 season, an increase of 2.6 percentage points from the prior season. Flu vaccination coverage has increased for both children and adults over the past two flu seasons. However, racial/ethnic disparities in flu vaccination coverage persisted. Non-Hispanic black children had lower flu vaccination coverage than children in all other racial/ethnic groups, while Hispanic adults and non-Hispanic black adults had lower flu vaccination coverage than non-Hispanic white adults. Interpretation of the estimates in this report should take into account limitations of the surveys, including reliance on self- or parental-report of vaccination status and low response rates, as well as level of consistency with findings from other surveys and data sources.

Getting a flu vaccine will be more important than ever this fall and winter, because it is likely that flu viruses and the virus that causes COVID-19 will both be spreading in the United States. Flu vaccination could help prevent or reduce the severity of flu illness, and reduction of outpatient illnesses, hospitalizations, and intensive care unit admissions could alleviate stress on the U.S. health care system. September and October are good times to get vaccinated; however, as long as flu viruses are circulating, vaccination should continue. To avoid missed opportunities for vaccination, providers should offer vaccination during routine health care visits and hospitalizations. Guidance for vaccine planning during the COVID-19 pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html.

Métodos

Para este informe, los CDC anallizaron los datos de la NIS-Flu para niños de 6 meses a 17 años y del BRFSS para adultos ≥ de 18 años con el propósito de estimar la cobertura de vacunación contra la influenza a nivel estatal y nacional durante la temporada de influenza 2019-20. Los análisis incluyeron datos recogidos de entrevistas realizadas durante septiembre (BRFSS) u octubre (NIS-Flu) del 2019 hasta junio del 2020 y el informe sobre las vacunaciones recibidas entre el 1 de julio del 2019 y el momento de la entrevista o antes del 31 de mayo del 2020 para los que fueron entrevistados en junio.

La NIS-Flu es una encuesta telefónica nacional que se realiza llamando al azar a números de teléfonos celulares de casas de familia.2 Respondents ≥18 years knowledgeable about the child's vaccinations (hereafter referred to as "parent" in this report) were asked if their child had received a flu vaccination since July 1, 2019, and, if so, in which month; this information was parent-reported and not verified by medical records. For the 18,2 % of respondents who indicated their child had been vaccinated but had a missing month of vaccination, month was imputed from other survey respondents with non-missing month of vaccination, matched for week of interview, age group, state of residence, and race/ethnicity. Respondents who indicated the child received a flu vaccination were also asked the kind of place at which the child was vaccinated. El índice de respuestas de la Council of American Survey and Research Organizations (CASRO) para la NIS-Flu durante la temporada 2019-20 fue del 19,6 % - 21,6 %. The estimates for children are based on n=153 533 completed NIS-Flu interviews.

BRFSS es una encuesta telefónica estatal que se realiza llamando al azar a números de teléfonos fijos o celulares para recabar información sobre diferentes condiciones médicas y comportamientos de riesgo de personas ≥ de 18 años seleccionadas en forma aleatoria. BRFSS includes survey questions asking whether the respondent had received a flu vaccination in the past 12 months, and if so, in which month and year. Las respuestas a las preguntas sobre el estado de la vacunación contra la influenza no fueron verificadas por registros médicos. Los encuestados que no respondieron de manera afirmativa o negativa a la pregunta sobre el estado de vacunación contra la influenza fueron excluidos del análisis, entre estos, 0,4 % respondieron que no sabían, 0,1 % se negaron a responder dicha pregunta y 6,8 % probablemente terminaron la entrevista antes de que se formule la pregunta sobre la influenza. Para el 6,6 % de los participantes de la encuesta del BRFSS que respondieron que habían sido vacunados pero que no recordaban el mes o año de vacunación, se imputó el mes de vacunación de otros encuestados que recordaban el mes de vacunación correspondiente a la semana de entrevistas, grupo etario, estado de residencia y raza/etnia. Information on high-risk conditions was missing for 1,2 % of adults; these respondents were not included in the estimates by risk condition. Estimates are not available for the entire 2019-20 influenza season from the District of Columbia; BRFSS calls in the District of Columbia did not occur during January-June 2020. In addition, calls in New Jersey did not occur during September 2019-April 2020, and estimates are based on interview data from May-June, 2020. El índice promedio de respuesta del BRFSS estatal para una entrevista completa o parcialmente completa fue del 49,4 % durante septiembre-diciembre del 2019 y del 48,3 % durante enero-junio del 2020. The estimates for adults are based on n=286 116 completed BRFSS interviews.

Las estimaciones de la cobertura de vacunación contra la influenza de ambas encuestas se calcularon mediante el análisis de supervivencia Kaplan-Meier con el mes de vacunación reportado para determinar la cobertura acumulativa de la vacunación contra la influenza. El cálculo de la cobertura para personas ≥ de 6 meses se determinó mediante cálculos mensuales combinados a nivel estatal ponderados por poblaciones de edades específicas de cada estado.3 Todas las estimaciones fueron ponderadas y analizadas con los programas estadísticos SAS y SUDAAN para justificar el complejo diseño de la encuesta. For simplified graphical display, only four racial/ethnic groups are displayed (Hispanic, non-Hispanic white only, non-Hispanic black only, and non-Hispanic all other races or multiple races); a more detailed racial/ethnic breakdown of estimates is included as a table weblink in the report. Differences between groups and between 2019-20 and prior season (2018-19) estimates were determined using t-tests with significance at p<0.05. Los aumentos o las disminuciones mencionadas en este informe registraron diferencias estadísticamente significativas.

Resultados

Niños (de 6 meses a 17 años)

Among children 6 months through 17 years, the percentage receiving ≥1 dose of flu vaccine during the 2019-20 season was 63,7 %, which was 1.2 percentage points higher than coverage in the 2018-19 season (62,5 %; Figure 1). Flu vaccination coverage increased 2 percentage points among children 6 months-4 years, but coverage did not significantly increase among children 5-12 or children 13-17 years compared with the 2018-19 season (Figure 1). As observed in previous flu seasons, flu vaccination coverage was lower for older compared with younger children.

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There was large between-state variability in flu vaccination coverage among children, ranging from 51,5 % (Mississippi) to 78,3 % (Rhode Island; Figure 2). See the interactive FluVaxView application for additional state-level estimates by age-groups and multiple flu seasons.

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Flu vaccination coverage for Hispanic children and non-Hispanic black children during the 2019-20 season did not show statistically significant changes compared with the 2018-19 season, while non-Hispanic white children and children in the non-Hispanic other race/ethnicity group had increases in coverage (Figure 3). Significant differences in flu vaccination coverage were observed between racial/ethnic groups. Non-Hispanic black children had lower flu vaccination coverage than children in all other racial/ethnic groups. Children in the other race/ethnicity group had higher flu vaccination coverage than non-Hispanic black, non-Hispanic white, and Hispanic children. In addition to the previous comparisons, non-Hispanic white children had lower flu vaccination coverage than Hispanic children. No other statistically significant pair-wise differences were observed. Flu vaccination coverage estimates for more detailed racial/ethnic groups (Asian, American Indian/Alaska Native, other or multiple races) is provided as a table weblink in the "Cálculos adicionales de la cobertura de vacunación contra la influenza" section of this report.

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Adultos (18 años en adelante)

Overall, among adults ≥18 years, flu vaccination coverage was 48,4 %, 3.1 percentage points higher than coverage during the 2018-19 season (45,3 %; Figure 4). Flu vaccination coverage for 2019-20 was higher for every age group compared with the 2018-19 season (Figure 4). As observed in previous seasons, flu vaccination coverage was higher for older adults compared with younger adults.

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There was large between-state variability in flu vaccination coverage among adults, ranging from 41,4 % in Idaho to 56,8 % in Massachusetts and Rhode Island (Figure 5). See the interactive FluVaxView application for additional state-level estimates by age-groups and multiple flu seasons.

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Flu vaccination coverage for Hispanic adults and non-Hispanic black adults during the 2019-20 season did not show statistically significant changes compared with the 2018-19 season, while non-Hispanic white adults and other race/ethnicity adults had increases in coverage (Figure 6). Similar to the 2018-19 season, differences in flu vaccination coverage were observed between racial/ethnic groups. Non-Hispanic white adults had higher flu coverage than non-Hispanic black, Hispanic, and adults of other racial/ethnic groups. Additionally, Hispanic and non-Hispanic black adults had lower flu vaccination coverage than adults of other racial/ethnic groups. Lastly, Hispanic adults also had lower coverage than non-Hispanic black adults. No other statistically significant pair-wise differences were observed. Flu vaccination coverage estimates for more detailed racial/ethnic groups (Asian, American Indian/Alaska Native, other or multiple races) is provided as a table weblink in the "Cálculos adicionales de la cobertura de vacunación contra la influenza" section of this report.

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All people 6 months and older

Among all people ≥6 months, the percentage vaccinated during the 2019-20 season was 51,8 %, 2.6 percentage points higher than coverage in the 2018-19 season (49,2 %; Table 1). Coverage during the 2019-20 season increased for white people and people of other non-Hispanic race but did not increase for black or Hispanic people (Table 1). White people had higher flu coverage than black, Hispanic, and other people. Additionally, people of non-Hispanic other races had higher coverage than black and Hispanic people. No other statistically significant pair-wise differences were observed.

Table 1. Flu Vaccination Coverage^* among All People 6 months and older, by Race/Ethnicity, United States,^† 2019–20 Season

Table 1. Flu Vaccination Coverage* among All People 6 months and older, by Race/Ethnicity, United States,† 2019–20 Season

Raza/etnia‡	%§ ± 95 % CI||	Diferencia con la temporada 2018-19, ± 95 % CI
Total	51.8 ± 0.5	2.6 ± 0.6¶
Solo blancos, no hispanos	54.8 ± 0.5	3.8 ± 0.6¶
Solo de color, no hispanos	45.6 ± 1.2	0.9 ± 1.8
Hispanos	46.6 ± 1.7	0.1 ± 2
Other, non-Hispanic**	51.8 ± 2	4.2 ± 2.4¶

_{* Estimates of the percentage vaccinated are based on interviews conducted September (BRFSS) or October (NIS-Flu) 2019 through June 2020 and reported vaccinations from July 2019 through May 2020.}

_{† No incluye los territorios de los EE. UU.}

_{‡ Race is self-reported; people of Hispanic ethnicity may be of any race.}

_{§ Porcentaje de vacunados. Los porcentajes se ponderan según la población de EE.UU. El mes de vacunación fue imputado en el caso de las personas encuestadas que no contaban con la información de vacunación del mes faltante.}

_{|| Amplitudes medias de intervalos de confianza (IC).}

_{¶ Statistically significant difference between the 2019–20 season and the 2018–19 season by t-test (p<0.05).}

_{** Includes Asian, American Indian/Alaska Native, Native Hawaiian or other Pacific Islander, multiracial, and other races.}

Lugar de vacunación

Place of flu vaccination among vaccinated children 6 months through 17 years was most often a doctor's office (69 %), followed by clinic/health center (14 %), and pharmacy (7 %; figura 7). A weblink to place of flu vaccination by child age groups is included in the additional tables in the next section of this report. Place of flu vaccination for adults from BRFSS is not available for the 2019–20 season; it is collected every 3^rd year. The most recent adult place of flu vaccination report is available in Figure 5 at the following link: FluVaxView.

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Cálculos adicionales de la cobertura de vacunación contra la influenza

Niños:

• Cobertura de vacunación contra la influenza por grupo etario, en niños, Estados Unidos, temporada 2019-20
• Cobertura de vacunación contra la influenza por sexo, en niños, Estados Unidos, temporada 2010-20 
• Cobertura de vacunación contra la influenza por raza-etnia y grupo etario, en niños, Estados Unidos, temporada 2019-20 
• Cobertura de vacunación contra la influenza por áreas locales y territorios, en niños, temporada 2019-20
• Lugar de vacunación contra la influenza, en niños, Estados Unidos, temporada 2019-20 

Adultos:

• Flu Vaccination Coverage, by Age Group and High Risk Status, Adults, United States, 2019–20 Season
• Cobertura de vacunación contra la influenza por sexo, en adultos, Estados Unidos, temporada 2019-20 
• Cobertura de vacunación contra la influenza, por raza/etnia y grupo etario, adultos, Estados Unidos, temporada 2019-20 
• Cobertura de vacunación contra la influenza, por áreas locales y territorios, adultos, temporada 2019-20

Limitaciones

Interpretation of the results in this report should take into account several limitations of the estimates produced from the NIS-Flu and BRFSS surveys. First, survey weighting adjustments may not eliminate all the possible bias from incomplete sample frames; both surveys exclude households with no telephones, and NIS-Flu also excludes households with only landline telephones. Second, response rates for both surveys were low, and flu vaccination coverage may differ between survey respondents and non-respondents; survey weighting adjustments may not adequately control for these differences. Third, there may be errors in flu vaccination status due to recall error of parents for NIS-Flu and of respondents for BRFSS.45 Cuarto, los errores de entorno de muestreo incompleto, la falta de respuesta y la precisión del estado de vacunación contra la influenza puede cambiar con el tiempo, lo que podría generar una evaluación imprecisa de las tendencias en la cobertura de vacunación contra la influenza. Fifth, due to BRFSS interviews not being completed in all months, adult estimates for New Jersey may be subject to differential bias compared with estimates based on the full set of interviews from September 2019-June 2020, and adult estimates for the District of Columbia represent vaccination coverage through November rather than through May. The projected DC vaccination coverage estimate for adults would be 55,3 % through May 2020, applying the relative increase in DC estimates from November 2017 to May 2018 to the 49,3 % estimate for the 2019-20 season. Sixth, estimates differed from National Health Interview Survey (NHIS) estimates, the data source for evaluating progress toward the Healthy People 2020 and 2030 flu vaccination coverage objectives; NHIS uses a different sampling method and in-person interviews but does also rely on self or parental report.67 A recent study found that NIS-Flu estimates were generally higher than NHIS estimates over several flu seasons for children.8 CDC continues to assess consistency between flu vaccination coverage estimates from different surveys and other data sources and evaluate accuracy of estimates from these data sources. For example, given the total number of doses of flu vaccine distributed in the United States in 2019-20 and population estimates, the maximum percentage of all people 6 months and older that could have been vaccinated was 55 %. Although 52 % were vaccinated according to the results in this report, this estimate may not be the actual proportion vaccinated given the limitations stated above.

CDC is exploring non-survey data sources to track flu vaccination coverage such as claims and other administrative data. While the NIS-Flu estimates for children are available weekly to CDC during the flu season, BRFSS data are not available to produce weekly estimates for adults for flu vaccination. To provide within-season weekly estimates of flu vaccination for adults, CDC acquired projected estimates based on claims data of the number of flu vaccines given at pharmacies in the United States from IQVIA. IQVIA claims-derived flu vaccination coverage was calculated using these projected estimates along with estimates of the percentage of vaccinated adults who received their flu vaccination at a pharmacy in each state (based on BRFSS surveys). The IQVIA claims-derived estimates for the end of flu season coverage from past seasons can be compared with existing estimates based on BRFSS. For national-level estimates, IQVIA claims-derived estimates were within five percentage points of the BRFSS estimates for the 2019-20 and two previous flu seasons. However, state-level estimates show more variability; for the 2018-19 season IQVIA claims-derived and BRFSS estimates differed between 0.5 and 35.5 percentage points across states for 18-64 year-old adults and 0.6 and 34.6 percentage points for adults 65 years and older. CDC continues to evaluate ways to improve the accuracy of IQVIA claims-derived flu vaccination coverage estimates, and plans to launch a Weekly Flu Vaccination Dashboard online via FluVaxView during the fall of 2020, including the IQVIA claims-derived estimates for adults and the weekly NIS-Flu estimates for children.

Discusión

Flu vaccination coverage during the 2019-20 season was higher than coverage during the 2018-19 season for both children and adults. For several seasons prior to the 2018-19 season, flu vaccination coverage had remained the same for children.8 For adults, there was a sizable increase in coverage for the last two consecutive seasons after many flu seasons of small increases, and one recent season with a decrease (though this decrease in 2017-18 was not confirmed by other data sources).9 Yet, despite these increases, the Healthy People 2020 national target of 70 % of children and adults vaccinated against flu was not achieved, with coverage lagging by 6 percentage points for children and almost 20 percentage points for adults.10 Reflecting this lack of substantial progress for adults, the newly launched Healthy People 2030 target for flu vaccination of persons ≥6 months has also been set at 70 %.7 Furthermore, flu vaccination coverage in some states and among some racial/ethnic groups is still far from optimal.

Getting a flu vaccine is more important than ever this fall and winter because flu and COVID-19 may both be spreading in the United States at the same time. CDC recommends that all people 6 months and older get a yearly flu vaccine, with rare exceptions. La vacunación las personas con alto riesgo es particularmente importante para disminuir el riesgo de padecer enfermedades graves por la influenza. Many people at higher risk from flu complications also are at higher risk from COVID-19. Getting a flu vaccine will not protect against COVID-19; however, flu vaccination has many other important beneficios. Se ha demostrado que la vacuna contra la influenza reduce el riesgo de influenza, hospitalización y muerte.

A flu vaccination not only reduces a person's risk from flu but may also help conserve potentially scarce healthcare resources. Durante la pandemia de COVID-19, reducir la carga general de las enfermedades respiratorias es importante para proteger a las poblaciones vulnerables con mayor riesgo de enfermarse gravemente, el sistema de atención médica y otras infraestructuras críticas. Thus, healthcare providers should use every opportunity during the flu vaccination season to administer flu vaccines to all eligible persons.

September and October are good times to get vaccinated; however, as long as flu viruses are circulating vaccination should continue. For the 2020-21 season, vaccine manufacturers have projected they will provide as many as 194-198 million doses of flu vaccine, which is more than the 175 million dose record set during the 2019-20 flu season.

How and where people get a flu vaccine may change due to the COVID-19 pandemic. Healthcare providers can find a collection of federal resources designed to guide vaccine planning during the COVID-19 pandemic at https://www.cdc.gov/vaccines/pandemic-guidance/index.html. CDC is working with healthcare providers and state and local health departments to develop contingency plans on how to vaccinate people against flu without increasing their risk of exposure to the virus that causes COVID-19. Some settings that usually provide flu vaccination, like workplaces and schools, may not offer vaccination this upcoming season because of challenges with maintaining social distancing. When going to get a flu vaccination, people should adoptar medidas de prevención cotidianas and follow CDC recommendations for lowering the risk of catching flu or COVID-19. People can ask their doctor, pharmacist, or health department if they are following CDC's vaccination pandemic guidance. Any vaccination location following CDC's guidance should be a safe place to get a flu vaccine. Para obtener más información, visite https://www.cdc.gov/flu/season/faq-flu-season-2020-2021.htm.