Interim Estimates of 2022–23 Seasonal Influenza Vaccine Effectiveness — Wisconsin, October 2022–February 2023

In the United States, 2022-23 influenza activity began earlier than usual, increasing in October 2022, and has been associated with high rates of hospitalizations among children* (1). Influenza A(H3N2) represented most influenza viruses detected and subtyped during this period, but A(H1N1)pdm09 viruses cocirculated as well. Most viruses characterized were in the same genetic subclade as and antigenically similar to the viruses included in the 2022-23 Northern Hemisphere influenza vaccine (1,2). Effectiveness of influenza vaccine varies by season, influenza virus subtype, and antigenic match with circulating viruses. This interim report used data from two concurrent studies conducted at Marshfield Clinic Health System (MCHS) in Wisconsin during October 23, 2022-February 10, 2023, to estimate influenza vaccine effectiveness (VE). Overall, VE was 54% against medically attended outpatient acute respiratory illness (ARI) associated with laboratory-confirmed influenza A among patients aged 6 months-64 years. In a community cohort of children and adolescents aged <18 years, VE was 71% against symptomatic laboratory-confirmed influenza A virus infection. These interim analyses indicate that influenza vaccination substantially reduced the risk for medically attended influenza among persons aged <65 years and for symptomatic influenza in children and adolescents. Annual influenza vaccination is the best strategy for preventing influenza and its complications. CDC recommends that health care providers continue to administer annual influenza vaccine to persons aged ≥6 months as long as influenza viruses are circulating (2).

In the United States, 2022-23 influenza activity began earlier than usual, increasing in October 2022, and has been associated with high rates of hospitalizations among children* (1). Influenza A(H3N2) represented most influenza viruses detected and subtyped during this period, but A(H1N1) pdm09 viruses cocirculated as well. Most viruses characterized were in the same genetic subclade as and antigenically similar to the viruses included in the 2022-23 Northern Hemisphere influenza vaccine (1,2). Effectiveness of influenza vaccine varies by season, influenza virus subtype, and antigenic match with circulating viruses. This interim report used data from two concurrent studies conducted at Marshfield Clinic Health System (MCHS) in Wisconsin during October 23, 2022-February 10, 2023, to estimate influenza vaccine effectiveness (VE). Overall, VE was 54% against medically attended outpatient acute respiratory illness (ARI) associated with laboratory-confirmed influenza A among patients aged 6 months-64 years. In a community cohort of children and adolescents aged <18 years, VE was 71% against symptomatic laboratory-confirmed influenza A virus infection. These interim analyses indicate that influenza vaccination substantially reduced the risk for medically attended influenza among persons aged <65 years and for symptomatic influenza in children and adolescents. Annual influenza vaccination is the best strategy for preventing influenza and its complications. CDC recommends that health care providers continue to administer annual influenza vaccine to persons aged ≥6 months as long as influenza viruses are circulating (2). * Routine influenza surveillance in the United States indicated that influenza viruses began to circulate and outpatient visits for influenza-like illness were increased above seasonal baseline levels in epidemiologic week 40 (the week ending October 8, 2022).
VE against medically attended influenza was estimated using a test-negative case-control design. Patients aged 6 months-64 years were actively recruited during or after outpatient medical care for ARI (i.e., telehealth, primary care, urgent care, or emergency department), and before or during appointments for clinical testing for SARS-CoV-2 at selected MCHS facilities. Patients were eligible if they had a cough of ≤7 days' duration and had not taken an influenza antiviral medication. Participants completed a brief survey and provided a respiratory specimen for influenza and SARS-CoV-2 testing. Participants who received a positive real-time reverse transcription-polymerase chain reaction (RT-PCR) test result for SARS-CoV-2 were excluded from VE estimation. Participants were considered vaccinated if MCHS health records indicated receipt of seasonal influenza vaccine according to Advisory Committee on Immunization Practices (ACIP) recommendations ≥14 days before illness onset † (2). VE against influenza A viruses and against influenza A(H3N2) viruses was estimated as 100% x (1 − adjusted odds ratio [aOR]). The aOR is the ratio of the odds of vaccination among those who received a positive influenza test result (case-patients) to the odds of vaccination among those who received negative test results for influenza and SARS-CoV-2 (control-patients). Estimates were adjusted for age, month of illness onset, and self-reported presence of one or more higher-risk condition § using logistic regression.
VE against symptomatic influenza in children and adolescents was estimated from an ongoing, prospective, † Persons aged ≥6 months are recommended to receive annual influenza vaccination.
Certain children aged 6 months-8 years need 2 doses of influenza vaccine, depending on influenza vaccination history. Persons aged ≥9 years are recommended to receive 1 dose of influenza vaccine each year, regardless of influenza vaccination history. For the test-negative case-control design analysis, children aged 6 months-8 years were excluded if they needed 2 doses and, at the time of illness, they had received only 1 dose of influenza vaccine ≥14 days earlier, meaning that they were partially vaccinated. For the cohort study, children aged 6 months-8 years were excluded from the study at the time of the first dose if they needed 2 doses and they had received only 1 dose of influenza vaccine. § Based on self-report of asthma or another chronic lung disease, cancer, diabetes, heart disease including high blood pressure, immunocompromising condition, kidney disease, liver disease, obesity, or pregnancy in the 12 months preceding the test-negative case-control study enrollment and self-report of asthma, immunocompromised state, serious heart condition, or other chronic lung disease for the community cohort study. community-cohort study in central Wisconsin (3). Each week, participants (or their guardians) reported the absence or presence of specific symptoms during the previous 7 days. An anterior nasal swab was self-or guardian-collected for research testing when participants reported one or more of the following: fever, cough, loss of smell or taste, sore throat, muscle or body aches, shortness of breath, diarrhea, nasal congestion or runny nose, or nausea or vomiting. Influenza infection was defined as a positive result from research testing or a positive result from clinical testing (results extracted from MCHS health records). Unvaccinated person-time was defined as the time from October 23, 2022 (7 days before occurrence of the first influenza case), until receipt of seasonal influenza vaccine. Vaccinated person-time began ≥14 days after receipt of influenza vaccine (based on health records) according to ACIP recommendations. Person-time for the 13 days after receipt of vaccine was excluded from the analysis. Hazard ratios comparing the rate of influenza A virus infection among vaccinated and unvaccinated participants were estimated using Cox proportional hazards models with time-varying influenza vaccination status, age, the presence of one or more higherrisk condition, and COVID-19 vaccination status. VE was estimated as 100% x (1 − adjusted hazard ratio , with receipt of vaccine ≤13 days before illness (four), or who were aged <9 years and partially vaccinated (seven) were excluded from analysis. † One child was partially vaccinated according to ACIP recommendations before the analysis period and was excluded. § Defined as receipt of any seasonal influenza vaccine according to ACIP recommendations ≥14 days before illness onset based on MCHS vaccination records. Most vaccinated participants (84%) received ccIIV4. ¶ Defined as receipt of seasonal influenza vaccine according to ACIP recommendations ≥14 days before influenza infection or before the end of follow-up based on MCHS vaccination records. Most vaccinated participants (84%) received ccIIV4. ** Age on the date of the clinical encounter for acute respiratory illness for the test-negative case-control study and as of September 1, 2022, for the community cohort study. † † Includes persons who are American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or other Pacific Islander, and multiracial. § § Based on self-report of asthma or another chronic lung disease, cancer, diabetes, heart disease including high blood pressure, immunocompromising condition, kidney disease, liver disease, obesity, or pregnancy during the 12 months preceding the test-negative case-control study enrollment and self-report of asthma, immunocompromised state, serious heart condition, or other chronic lung disease for the community cohort study. ¶ ¶ Based on self-report for the test-negative case-control study and health records for the community cohort study. *** Includes cohort participants with acute respiratory illness who received negative influenza test results, those with no reported acute respiratory illness, and three persons with influenza infections occurring within 14 days after vaccination who were excluded from the study at the time of vaccination. † † † Column percentages. Abbreviations: aOR = adjusted odds ratio; NE = not estimated; VE = vaccine effectiveness. * VE was estimated using the test-negative design as 100% x (1 − aOR) in which aOR represents ratio of odds of being vaccinated among influenza-positive cases to odds of being vaccinated among influenza-negative and SARS-CoV-2-negative controls; odds ratios were estimated using logistic regression with adjustment for age, month of illness onset, and presence of one or more higher-risk condition (self-report of asthma or another chronic lung disease, cancer, diabetes, heart disease including high blood pressure, immunocompromising condition, kidney disease, liver disease, obesity, or pregnancy in the 12 months preceding enrollment). https:// www.cdc.gov/flu/vaccines-work/us-flu-ve-network.htm † VE was estimated from a Cox proportional hazards model with time-varying influenza vaccination status, age, presence of at least one higher-risk condition (self-report of asthma, immunocompromised state, serious heart condition, or other chronic lung disease), and receipt of ≥2 COVID-19 vaccine doses before the analysis period.
large majority of vaccinated participants (84%) received cell culture-based vaccine (ccIIV4). Among the 116 participants who received a positive influenza test result, 26 (22%) received the 2022-23 seasonal influenza vaccine, compared with 160 (37%) of 429 participants who received negative test results for influenza and SARS-CoV-2 ( Table 2). The overall adjusted VE against outpatient medically attended ARI associated with influenza A was 54% and 60% against influenza A(H3N2) viruses.
Among 241 community cohort participants aged 1-17 years, 94 (39%) had documented receipt of the 2022-23 influenza vaccine (Table 1); 84% received ccIIV4. Among community cohort participants who received the 2022-23 influenza vaccine, 65% had documentation of receipt of ≥2 COVID-19 vaccine doses. During October 23, 2022-February 10, 2023, 37 (15%) participants received a positive test result for influenza A virus infection; however, three of these occurred ≤14 days after influenza vaccination and were excluded from the study at the time of vaccination. Among the remaining 34 influenza virus infections included in the analysis, 29 were caused by A(H3N2),** one by A(H1N1)pdm09, and four by influenza A viruses with unknown subtype. Six children (18%) with influenza A had received the 2022-23 seasonal influenza vaccine. Among 15,678 unvaccinated person-days, 28 influenza A virus infections occurred (incidence = 1.79 per 1,000 person-days), and among 7,292 vaccinated person-days, six influenza A virus infections occurred (incidence = 0.82 per 1,000 person-days) ( Table 2). VE against symptomatic influenza A virus infection was 71%.

Discussion
Influenza activity for the 2022-23 winter season increased earlier than usual, with high rates of influenza-associated ** Six A(H3N2) viruses from the community cohort study were genetically characterized and belonged to subclade 2a.2.
hospitalizations among children (2). The interim estimates of 2022-23 influenza VE from two concurrent studies in Wisconsin suggest that the current season's influenza vaccines are providing substantial protection against influenza. These findings are consistent with estimates reported in the Southern Hemisphere for the 2022 season and Canada for the current season, where similar viruses predominated (4,5). However, influenza vaccination coverage in the United States this season has been lower than during pre-COVID-19 pandemic seasons, particularly among children, pregnant women, and in rural areas (6). Increased vaccination coverage is needed to realize the full potential of seasonal influenza vaccines. The interim estimates reported reflect early season VE and might differ from end-of-season VE estimates with additional enrollments, or if a change in circulating viruses would occur later in the season. Through the week ending February 4, 2023, influenza activity was low nationally. However, CDC continues to monitor influenza activity through routine surveillance for any indications that activity might increase again; two waves of influenza activity have occurred during many previous seasons (7). Seasonal influenza vaccines protect against influenza A and B viruses, both of which might continue or begin to circulate later in the season, resulting in potentially serious complications.
The findings in this report are subject to at least four limitations. First, the studies were restricted to participants from a single geographic area (central Wisconsin). However, viruses that predominated in the study population were similar to those that predominated across the United States (1). Second, older adults aged ≥65 years were excluded from the test-negative study. Age-specific VE estimates against influenza virus infection caused by A(H3N2) viruses are generally lower for older adults (8). Third, sample sizes were small for the interim analysis, which limited the precision of VE estimates, and VE against illness associated with A(H1N1)pdm09 virus infections

Summary
What is already known about this topic?
Effectiveness of influenza vaccine varies by season, influenza virus subtype, and antigenic match with circulating viruses.
What is added by this report?
Data from two concurrent studies in Wisconsin found that effectiveness of the 2022-23 influenza vaccine was 54% for preventing medically attended influenza A infection among persons aged <65 years and 71% for preventing symptomatic influenza A illness among children and adolescents aged <18 years.
What are the implications for public health practice?
The 2022-23 influenza vaccine provides substantial protection against circulating influenza A viruses and remains the best way to protect against influenza. Influenza vaccination is recommended as long as influenza viruses are circulating. and age-specific estimates could not be determined. Finally, confounding and bias are of concern with observational studies; however, estimates were comparable across two study designs, and the test-negative study design yields valid estimates of influenza VE in most scenarios (9).
Annual influenza vaccination is the best strategy for preventing influenza and its complications. During the 2022-23 season to date, influenza A viruses that predominated are genetically and antigenically similar to current vaccine components. Interim VE estimates from this report indicate that the current season's influenza vaccine substantially reduces the risk for medical visits among persons aged 6 months-64 years and symptomatic illness associated with influenza A virus infection among children and adolescents aged <18 years. Influenza vaccination is recommended for all persons aged ≥6 months for as long as influenza viruses are circulating in the community.

Effect of Predeparture Testing on Postarrival SARS-CoV-2-Positive Test Results Among International Travelers -CDC Traveler-Based Genomic Surveillance Program, Four U.S. Airports, March-September 2022
Stephen Beginning December 6, 2021, all international air passengers boarding flights to the United States were required to show either a negative result from a SARS-CoV-2 viral test taken ≤1 day before departure or proof of recovery from COVID-19 within the preceding 90 days (1). As of June 12, 2022, predeparture testing was no longer mandatory but remained recommended by CDC (2,3). Various modeling studies have estimated that predeparture testing the day before or the day of air travel reduces transmission or importation of SARS-CoV-2 by 31%-76% (4-7). Postarrival SARS-CoV-2 pooled testing data from CDC's Traveler-based Genomic Surveillance program were used to compare SARS-CoV-2 test results among volunteer travelers arriving at four U.S. airports during two 12-week periods: March 20-June 11, 2022, when predeparture testing was required, and June 12-September 3, 2022, when predeparture testing was not required. In a multivariable logistic regression model, pooled nasal swab specimens collected during March 20-June 11 were 52% less likely to be positive for SARS-CoV-2 than were those collected during June 12-September 3, after adjusting for COVID-19 incidence in the flight's country of origin, sample pool size, and collection airport (adjusted odds ratio [aOR] = 0.48, 95% CI = 0.39-0.58) (p<0.001). These findings support predeparture testing as a tool for reducing travel-associated SARS-CoV-2 transmission and provide important real-world evidence that can guide decisions for future outbreaks and pandemics.
The Traveler-based Genomic Surveillance Program conducts surveillance of travelers at international airports for early detection of new and emerging SARS-CoV-2 variants and to fill gaps in international surveillance (8). International travelers aged ≥18 years arriving at airports in Newark, New Jersey (Newark Liberty Airport); New York, New York (John F. Kennedy International Airport); Atlanta, Georgia (Hartsfield-Jackson Atlanta International Airport); and San Francisco, California (San Francisco International Airport), who volunteered to participate provided a postarrival lower nasal swab sample in the airport (8). After providing signed consent, participants completed a standardized survey that included questions regarding demographic characteristics, flight country of origin, and whether predeparture testing had occurred and, if so, whether an antigen or molecular test had been performed. In the airport, dry nasal swab samples were pooled (5-25 samples per pool) by the flight country of origin. Pooled samples were sent to a laboratory in the Ginkgo Bioworks laboratory network for SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) testing (8).
Postarrival RT-PCR testing results during March 20-June 11, when the predeparture test requirement was in effect, were compared with those during June 12-September 3, when predeparture testing was voluntary. To account for worldwide differences in COVID-19 incidence, pooled test results were matched with daily 7-day average country-level COVID-19 incidence (cases per 100,000 population) from the World Health Organization* based on pool collection date and the flight country of origin. To account for reporting differences by country, normalized incidence was estimated by dividing the 7-day average COVID-19 incidence on the date of pool collection for the flight country of origin by the maximum 7-day average daily incidence for that country during March 20-September 3, then multiplying by 100.
To identify factors associated with positive postarrival SARS-CoV-2 pooled test results, bivariate comparisons and univariable logistic regression were performed. Factors with significant univariable associations (p<0.05) were incorporated into a multivariable mixed effects logistic regression model that included collection airport as a random effect. Alternative periods (during the 4-8 weeks preceding June 12 and those on or after that date) were considered in sensitivity analyses. Analyses were conducted in R (version 4.0.2; R Foundation). This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy. † During March 20-September 3, 2022, a total of 28,056 arriving travelers from 24 countries received testing for SARS-CoV-2, yielding 3,049 pooled samples with a median of eight participant samples per pool (range = 5-25). During March 20-June 11, among 16,668 Traveler-based Genomic Surveillance participants, 13,190 (79.1%) reported having had a predeparture test; during June 12-September 3, this percentage declined by 80% to 1,786 of 11,123 (16.1%) participants reporting having had a predeparture test (Figure 1). Among  Table 1, https://stacks.cdc.gov/view/cdc/124584). The increase in the percentage of positive postarrival test results between March 20-June 11 and June 12-September 3 occurred across countries, collection airports, incidences, and pool sizes and was apparent in both bivariate analyses and univariable logistic regression. Participants during each period were similar in age and gender; however, during the period beginning June 12, fewer participants reported U.S. residency (Supplementary Table 2, https://stacks.cdc.gov/view/cdc/124585).
Multivariable model results showed that pools of samples collected during March 20-June 11 (when predeparture testing was mandatory) were 52% less likely to be positive than were those when predeparture testing was voluntary (aOR = 0.48, 95% CI = 0.39-0.58) (p<0.001), after adjusting for COVID-19 incidence in the flight's country of origin, pool size, and collection airport (Table). COVID-19 incidence in the flight's country of origin and pool size also remained significant predictors of positive pooled test results in the multivariable model.  Table 3, https://stacks.cdc.gov/ view/cdc/124586).

Discussion
Postarrival SARS-CoV-2 test results were 52% less likely to be positive when the predeparture COVID-19 testing requirement was in effect than during the 12-week period after it was discontinued; this finding was true even when controlling for other factors such as incidence in the flight's country of origin and pool size. These findings, based on observed, real-world traveler data, support the value of predeparture testing as a tool for reducing SARS-CoV-2 transmission associated with travel and were consistent with estimates from previous modeling studies (4)(5)(6)(7).
Sensitivity analyses using shorter time frames around removal of the predeparture testing requirement produced similar findings. Although still statistically significant, the magnitude of this effect decreased when 4-week windows were considered, possibly because of smaller sample sizes during the shorter time frame or higher rates of voluntary predeparture testing during the 4 weeks after the removal of the predeparture test requirement on June 12.
The findings in this report are subject to at least five limitations. First, because participation in the Traveler-based Genomic Surveillance Program is voluntary, results might not be representative of all international travelers; however, any participation bias was likely consistent across both periods. Second, because of the pooled sampling and testing strategy employed, trends among individual participants could not be assessed. Third, incidence data were matched with pooled test results based on a flight's country of origin, and it is possible that participants began their itinerary in a different country and later connected to the U.S.-bound flight. Fourth, as testing rates decline globally, reported incidence data might not fully reflect actual COVID-19 risk in a given country (9). Finally,   Abbreviation: OR = odds ratio. * John F. Kennedy International Airport, New York, New York; Newark Liberty International Airport, Newark, New Jersey; Hartsfield-Jackson Atlanta International Airport, Atlanta, Georgia; and San Francisco International Airport, San Francisco, California. † Incidence was normalized by dividing the 7-day average COVID-19 incidence (cases per 100,000 population) for the flight origin country on the date of collection by the maximum 7-day average daily incidence for that country during the analysis period and multiplying by 100.
not all travelers during March 20-June 11 had a predeparture test, such as those who recently had COVID-19 (1), and some travelers during June 12-September 3 voluntarily chose to test, potentially diminishing this estimate of the effect of predeparture testing. Reducing the number of persons traveling while infected with SARS-CoV-2 through predeparture testing could reduce air travel-associated transmission in airports, aircraft, and destination communities. CDC continues to recommend testing before and after international travel (3). Along with other strategies, including isolation of persons with confirmed or suspected COVID-19 and masking, testing before international travel is an important element of a multipronged COVID-19 prevention strategy. In December 2022, results from this analysis were used alongside other evidence to support a predeparture test requirement for travelers boarding flights to the United States from China to slow importation of SARS-CoV-2 during a surge in COVID-19 cases there (10). These findings provide important real-world evidence supporting the effectiveness of predeparture testing that can guide decisions for future outbreaks and pandemics. * Adjusted odds ratio point estimates are relative to each Ref with 95% CIs. † Incidence was normalized by dividing the 7-day average COVID-19 incidence (cases per 100,000 population) for the flight origin country on the date of collection by the maximum 7-day average daily incidence for that country during the analysis period and multiplying by 100.

Summary
What is already known about this topic?
During December 6, 2021-June 11, 2022, SARS-CoV-2 testing ≤1 day before departure or proof of recent COVID-19 recovery were required for passengers boarding U.S.-bound flights. Mathematical models have estimated predeparture testing effectiveness in preventing travel-associated transmission.
What is added by this report?
What are the implications for public health practice?
Predeparture testing can reduce SARS-CoV-2 transmission risk during or after travel by reducing the number of infectious travelers. These results can help guide decisions for future outbreaks.
As SARS-CoV-2 testing declines worldwide, surveillance of international travelers for SARS-CoV-2 enables detection of emerging variants and fills gaps in global genomic surveillance (1). Because SARS-CoV-2 can be detected in feces and urine of some infected persons (2), wastewater surveillance in airports and on aircraft has been proposed by the global public health community † as a low-cost mechanism to monitor SARS-CoV-2 variants entering the United States. Sampling wastewater directly from aircraft can be used to link SARS-CoV-2 lineage data with flight origin countries without active engagement of travelers (3).
During August 1-September 9, 2022, the biotech company Ginkgo Bioworks, in collaboration with CDC, evaluated the feasibility of SARS-CoV-2 variant detection in aircraft wastewater from incoming international flights. Aircraft wastewater samples were collected from selected flights from the United Kingdom, Netherlands, and France arriving at John F. Kennedy International Airport in New York City. Wastewater (approximately 0.25 gal [1 L]) was collected from each plane during normal maintenance using a device that attaches to the lavatory service panel port and the lavatory service truck hose.
Pangolin (version 4.1.3) § § and reported to the airline, public SARS-CoV-2 genomic data repositories, and the CDC National Wastewater Surveillance System. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy. ¶ ¶ During August 1-September 9, 2022, one sample was collected from each of 88 flights (Figure). Sample collection added approximately 3 minutes to normal aircraft maintenance times. Eighty samples were tested for SARS-CoV-2.*** Overall, 65 samples (81%) were positive; the percentage that were positive was similar among the three flight origin countries sampled ( This investigation demonstrated the feasibility of aircraft wastewater surveillance as a low-resource approach compared with individual testing to monitor SARS-CoV-2 variants without direct traveler involvement or disruption to airport operations. Limitations include dependence on lavatory use during the flight, which correlates with flight duration (5); inability to distinguish travelers with connecting flight itineraries, which lessens precision when ascertaining variant origin; and potential carryover of residual SARS-CoV-2 RNA between flights yielding viral detections unrelated to travelers on the flight. Stringent genome coverage thresholds might reduce the likelihood of carryover variant identification on subsequent flights.
In  versus 29%), identified as Black (28% versus 20%), and had a COVID-19 hospitalization (7% versus 6%), the percentage with COVID-19 deaths was the same (1%) among all patients with laboratory-confirmed cases, irrespective of sequencing status. XBB.1.5 emerged rapidly in NYC during November-December 2022 and earlier than in the rest of the United States. Preliminary findings from a sample of sequenced isolates in NYC do not suggest more severe disease among patients infected with XBB.1.5 compared with patients infected with BQ.1; however, these findings might change as more data on these outcomes accumulate. Although a small proportion of laboratory-confirmed SARS-CoV-2 cases in NYC are sequenced, linked epidemiologic and genomic data provide a means to evaluate characteristics of emerging variants, including disease severity, that are important for rapid risk assessment (3). Routine linkage of epidemiologic and sequencing data allows tracking of emerging variants and ongoing assessment of reinfection, infection after vaccination, and disease severity. US Department of Health and Human Services/Centers for Disease Control and Prevention * With 95% CIs indicated by error bars. † Serious psychological distress is based on responses to six questions, "During the past 30 days, how often did you feel 1) so sad that nothing could cheer you up, 2) nervous, 3) restless or fidgety, 4) hopeless, 5) that everything was an effort, or 6) worthless?" The response options "none of the time," "a little of the time," "some of the time," "most of the time," and "all of the time" were each scored from 0-4 points, respectively, and then summed for a total score ranging from 0-24 points. A value of ≥13 was used to define serious psychological distress. Only respondents who answered all six questions were included in the analysis. § Estimates are based on household interviews of a sample of the civilian, noninstitutionalized U.S. population.
In 2021, 3.7% of adults aged ≥18 years had serious psychological distress in the past 30 days with percentages higher among women (4.6%) than among men (2.7%). The higher percentages among women were seen across all age groups: 5.6% versus 3.1% in adults aged 18-44 years, 4.5% versus 2.8% in those aged 45-64 years, and 2.8% versus 1.7% in those aged ≥65 years. The percentage of women who had serious psychological distress in the past 30 days decreased with age; the percentage of men who had serious psychological distress in the past 30 days was higher among those aged 18-44 and 45-64 years than among those aged ≥65 years.