---
title: "Incidence of RSV in Adults ≥50 Years in the Upper Midwest After COVID-19: Community Cohort Finding"
id: "bmj-open-6-incidence-of-respiratory-syncytial-virus-in-adults-50-years-during-and"
canonical_url: "https://medichelpline.com/clinical-feed/bmj-open-6-incidence-of-respiratory-syncytial-virus-in-adults-50-years-during-and"
content_type: "clinical_feed_article"
specialty: "Infectious Disease"
source_name: "BMJ Open"
source_url: "http://bmjopen.bmj.com/cgi/content/short/16/7/e111773?rss=1"
published_at: "2026-07-21T12:12:52.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Incidence of RSV in Adults ≥50 Years in the Upper Midwest After COVID-19: Community Cohort Finding
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/bmj-open-6-incidence-of-respiratory-syncytial-virus-in-adults-50-years-during-and
- **Specialty:** [Infectious Disease](https://medichelpline.com/clinical-feed/infectious-disease.md)
- **Primary Source:** BMJ Open
- **Source URL:** [Original Journal Publication](http://bmjopen.bmj.com/cgi/content/short/16/7/e111773?rss=1)
- **Published At:** 2026-07-21T12:12:52.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- This community-based prospective cohort followed adults aged **≥50 years** in southeast Minnesota during October 2021–September 2023 to estimate community incidence of **RSV** acute respiratory infection (**RSV-ARI**). - The cohort included 2,500 participants at the start of year 3 (mean age 68.2 years, 60% female, 96% non-Hispanic white). Participants received primary care within the Mayo Clinic system. - Primary outcome: PCR-confirmed **RSV-ARI**; secondary outcomes: healthcare utilisation and complications (hospitalisation, pneumonia, death) within 4 weeks of ARI. - Incidence in 2021–2022 (year 3): 15 RSV-ARI cases, crude incidence 6.12/1000 person-years (PY) (95% CI 3.42–10.09), attack rate 0.60% (95% CI 0.34–0.99). Age-gender standardized incidence 6.17/1000 PY. - Incidence in 2022–2023 (year 4): 39 RSV-ARI cases, crude incidence 16.40/1000 PY (95% CI 11.66–22.42), attack rate 1.59% (95% CI 1.14–2.17). Age-gender standardized incidence 16.99/1000 PY. - Incidence increased 2.7-fold in 2022–2023 compared with 2021–2022; seasonal peaks occurred in December 2021 and November 2022. RSV B predominated in 2021–2022; RSV A predominated in 2022–2023. - No hospitalisations, pneumonia diagnoses, or deaths within 30 days of RSV-ARI were observed in the reported episodes; RSV-LRTD standardized incidence was 2.79/1000 PY in year 3 and 8.90/1000 PY in year 4. - Missing RSV test data occurred for 25% of ARI episodes (574/years 3–4), with ~70% of those testing positive for COVID-19 and therefore not swabbed for RSV; this likely underestimated RSV incidence. - Strengths: community-based design, prospective PCR verification across two respiratory seasons, prospective capture of healthcare utilisation. Limitations: single geographic location, single-collection PCR testing method, and non-testing of participants with active COVID-19 infection. - Authors conclude that RSV remained lower than pre-pandemic levels but rose substantially in 2022–2023, supporting continued public health relevance of **RSV** and the rationale for ongoing **RSV vaccination** efforts.
## Clinical Analysis & Structured Key Points
Skip to main content Intended for healthcare professionals Log In Basket Search for this keyword Advanced search Latest content Archive For authors About Browse by collection You are here Home Archive Volume 16, Issue 7 Email alerts Article Text Article info Citation Tools Share Rapid Responses Article metrics Alerts PDF Respiratory medicine Original research Incidence of respiratory syncytial virus in adults ≥50 years during and following the COVID-19 pandemic in upper midwest USA: a community-based prospective cohort study http://orcid.org/0000-0002-1891-309XPaul Y Takahashi1, Pouya Saeedi2, Chung-Il Wi3, Robert J Pignolo4, Wendelyn Bosch5, Katherine S King6, Joel Hickman6, Euijung Ryu6, Traci Natoli3, Kathy Ihrke3, Joseph Yao7, Matthew Binnicker7, Steph Sieler3, Lisa Speiser8, Brandon Hidaka9, Silvia Damaso2, Jean-Yves Pircon2, http://orcid.org/0000-0003-2112-4240Young Juhn3 Correspondence to Dr Paul Y Takahashi; takahashi.paul@mayo.edu Abstract Objective Respiratory syncytial virus (RSV) is an important viral pathogen in children, older adults and adults with certain high-risk conditions. In our prospective community-based cohort study of adults 50 years and older before the COVID-19 pandemic, the incidence of RSV acute respiratory infection (ARI) was 48.6 cases/1000 person-years (PY), which decreased to near zero during the COVID-19 pandemic. Our objective was to determine the incidence of RSV-ARI during the 2 years following the initial phase of the pandemic (2021–2022 and 2022–2023). Design This is a community-based prospective cohort study. Setting Adults living in southeast Minnesota from October 2021 to September 2022 (year 3) and October 2022 to September 2023 (year 4). Participants Adults≥50 years (n=2500). Primary and secondary outcomes We calculated incidence and attack rates for RSV-ARI as primary outcome and reported hospitalisations, pneumonia and death following ARI as secondary outcome. Results There were 2500 participants in the study with a mean age of 68.2 years (SD 9.3) at the start of year 3. Participants were predominantly female (60%), non-Hispanic white (96%) and residing in urban areas (76%). The incidence rate of RSV-ARI was 6.12/1000 PY (95% CI 3.42 to 10.09) in 2021–2022 and 16.40/1000 PY (95% CI 11.66 to 22.42) in 2022–2023. We noted higher attack rates of RSV-ARI during the winter months. There were no hospitalisations, pneumonia or deaths within 30 days of RSV-ARI. Conclusions Compared with the period before the COVID-19 pandemic, RSV-ARI incidence was lower in both 2021–2022 and 2022–2023 periods. In 2022–2023, the incidence increased 2.7-fold compared with the 2021–2022 period. The observed incidence rates, particularly the significant increase in the most recent season, underscore the continued public health relevance of RSV-ARI and support the rationale for ongoing RSV vaccination efforts to mitigate its overall burden in the population. Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: https://creativecommons.org/licenses/by-nc/4.0/. https://doi.org/10.1136/bmjopen-2025-111773 Request Permissions If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways. Request permissions STRENGTHS AND LIMITATIONS OF THIS STUDY Community-based, prospective cohort study of adults over 50. PCR-verified infection over two respiratory seasons. Prospective follow-up for healthcare utilisation and severe outcomes such as hospitalisation, pneumonia and death in adults ≥50 years. Single geographical location, use of single-collection PCR testing. Individuals with active COVID-19 infection were not tested for respiratory syncytial virus (RSV), leading to potential underestimation of RSV incidence. Background Respiratory syncytial virus (RSV) is an important cause of acute respiratory infection (ARI) in infants,1 older adults and adults with certain high-risk conditions.2–4 A community-based study from 1999 to 2003 found RSV annual incidence rate of 3–7% in healthy older adults aged ≥65 years, and 4–10% in adults aged ≥21 years with cardiac or pulmonary illnesses using nasal swabs with PCR collected by research personnel.5 The COVID-19 pandemic changed the incidence rates dramatically for all ARIs after initiation of public health measures.6 A decline in RSV infections was reported during the initial phase of the COVID-19 pandemic in 2020.7 However, RSV activity later rebounded,8 and the activity shifted in RSV epidemiology6 in patients coming to medical attention. Most research to date has focused on medically attended RSV, highlighting a gap in understanding community-level incidence, which is crucial for informing public health policy. Our study measured RSV incidence and its seasonal patterns after lifting of the public health measures (wearing masks, social distancing) following the COVID-19 pandemic9 in community-based adults aged 50 years and older. This study represents the final period prior to the use of RSV vaccines.3 RSV vaccines were first approved in the USA in May 2023 by the Food and Drug Administration (FDA) for the prevention of RSV lower respiratory tract disease (LRTD) for use in adults aged ≥60 years.3 In 2024, the FDA also approved RSV vaccines for adults aged 50–59 at increased risk for RSV disease.10 The RSV vaccines are currently recommended for all adults aged ≥75 years and adults aged 60–74 at increased risk for severe RSV disease (eg, adults with chronic cardiovascular disease, chronic lung or respiratory disease, chronic liver disease, chronic haematologic conditions, severe obesity, moderate or severe immune compromise, residence in a nursing home, etc).4 Our primary aim was to estimate the incidence of RSV in adults ≥50 years during two consecutive years, October 2021–September 2022 and October 2022–September 2023. The public health importance of understanding RSV incidence following the COVID-19 pandemic is substantial, and these findings may impact epidemiological work on future epidemics.11 Methods Study design, cohort description, recruitment and procedures This is an analysis for years 3 (October 2021–September 2022) and 4 (October 2022–September 2023) of a 4-year prospective cohort study, for which we previously reported the incidence of RSV-ARI during the first 2 years of the study (October 2019–September 2021).12 The original cohort and the study design are detailed elsewhere.12 Briefly, we conducted a prospective cohort study of community-dwelling participants 50 years and older living in southeastern Minnesota. We originally consented 2325 subjects in 2019 to participate for two consecutive RSV seasons,12 but with the onset of the COVID-19 pandemic, we extended the study during the non-RSV seasons (starting 1 May 2021) and followed subjects who reconsented for an additional 2.5 years (until 30 September 2023).13 We supplemented those who chose not to reconsent by inviting a new cohort of subjects to participate in the last 2 years (1 October 2021–30 September 2023) of the study.13 We used virtual recruitment strategies described previously.14 The inclusion criteria included the following: aged 50 years and above, living and receiving medical care within southeast Minnesota and a willingness to perform a self-collected nasal swab at home for subsequent lab-based RSV PCR testing.12 This differed compared with our previous report when patients did either self-swab or clinic swab; however, concordance between methods is generally about 90%.15 All participants used a primary care provider at Mayo Clinic (Rochester, Minnesota, USA) and received medical care in southeastern Minnesota. All participants provided written consent as well as authorisation for medical record review in accordance with Minnesota state statute 144.290-144.298.16 Participants were excluded if they did not meet age, residency or medical provider criteria or if they refused study procedures like nasal swabs. Participants were excluded from the initial cohort if they developed an ARI after 1 October 2019 and before their consent date. Participants were excluded if they were out of the study region for more than 2 weeks during the RSV season (October–April) or over 4 weeks during the non-RSV season (May–September) to ensure they could provide a self-swab when they developed ARI symptoms. Participants were also excluded if they were unable to ambulate, had cognitive impairment or if the investigators felt the participant could not complete the requirements of the study or had concerns for safety. These exclusions were added to ensure adequate compliance with swabs and ability to test frailty. We adhered to the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) guidelines for cohort studies.17 We conducted the study within the principles of the Declaration of Helsinki.18 Patient and public involvement None. Measurement of variables The primary outcome was the development of RSV-ARI. The definition of ARI has been described previously.12 ARI was defined as two or more upper respiratory tract symptoms or at least two signs/symptoms from different locations (upper, lower or systemic) for at least 24 hours (online supplemental table 1). LRTD was defined as at least two lower respiratory signs/symptoms for at least 24 hours or reduction in oxygen saturation (online supplemental table 1). Participants with ARI were placed in severity categories of mild, moderate and severe. Patients with mild ARI had upper respiratory tract infection symptoms only, without fever or systemic signs/symptoms. Moderate ARI involved systemic symptoms of infection with upper respiratory tract symptoms or symptoms requiring outpatient visits. Severe illness involved systemic symptoms of infection with lower respiratory symptoms or symptoms requiring emergency department visit or hospitalisation. When participants developed symptoms of ARI, they communicated with study staff to determine if their symptoms met ARI criteria. To minimise under-ascertainment by a lack of self-report, we conducted surveillance via the electronic medical record and communicated with participants if they had potential symptoms in the record. If they met the criteria, they were instructed to self-collect a nasal swab, as previously described,12 as long as they were not known to have COVID-19 (this was enacted during the early phase of pandemic to protect staff who interacted with the sample and continued throughout study). If patients were determined to have COVID-19, those patients did not swab for RSV and were considered missing for RSV. Self-collected specimens were tested for RSV using FDA-approved reverse transcription-PCR (RT-PCR) assays (Simplexa Flu A/B and RSV Direct, DiaSorin Molecular, Cypress CA; Panther Fusion Flu A/B and RSV Assay, Hologic). This PCR also tested for influenza A/B infection. Supplemental material [bmjopen-2025-111773supp001.pdf] We measured healthcare utilisation by outpatient visits, emergency department visits, hospitalisation, hospital length of stay and hospitalisation with intensive care unit (ICU) stay following respiratory infection within 4 weeks of ARI. We performed this analysis for hypothesis generation. We reported the ARI complications, including pneumonia, hospitalisation or death within 4 weeks of ARI. We obtained these healthcare outcomes by manual chart review of their visits to determine if the visit was related to their symptoms. Pneumonia was a clinical diagnosis as noted from chart abstraction for evaluation of outcomes. Mortality following ARI was determined using the electronic health record from previously described methods.19 We reported demographics of age, self-reported gender, race and ethnicity, using the electronic health record (EHR). Age was categorised into 10-year age groups, and gender reported as female or male (n and percentage). We reported race and ethnicity as non-Hispanic white, Hispanic or Latino, African American, American Indian/Alaskan Native, Asian and unknown. We classified living environment as rural, urban or missing (as defined by the US Census Bureau) by using their permanent address.20 We reported the history of congestive heart failure, asthma, chronic obstructive pulmonary disease and diabetes mellitus within 3 years from the start of year 3. For socioeconomic status (SES), we reported the HOUsing-based SocioEconomic Status (HOUSES) index in quartiles. The HOUSES index accounts for the characteristics of the home which includes four real property variables including the assessor’s value, housing square footage, number of bedrooms and bathrooms in the home.21 A low HOUSES quartile score indicates a lower SES and has been associated with adverse health outcomes in older adults.22 Data analysis procedure We analysed and reported RSV-ARI during and through the end of the COVID-19 omicron period of the pandemic. We divided the study period into 2 years, year 3 (1 October 2021–30 September 2022) and year 4 (1 October 2022–30 September 2023) and further divided each year into the RSV season (1 October –30 April) and non-RSV season (1 May–30 September). We expressed the incidence rate as the number of first RSV-positive respiratory cases per 1000 person-years (PY) with exact Poisson 95% CIs. To calculate PY, the beginning of follow-up was the date of the start of the time period (ie, given year). The end of the follow-up was the date of the end of the time period, the symptom onset of RSV-positive ARI (if occurred during the period) or last follow-up (moving out of region, death, discontinuation of the study) whichever came first. We expressed the attack rate as the percentage of participants with at least one RSV-positive ARI during the period with Clopper–Pearson Exact 95% CIs. We also included incidence rates standardised to the US population with white race by age and sex using the 2020 US Census with 95% CI using the normal approximation. We used this standardisation as it best represented the population in the study. Presence of complications and healthcare utilisations related to ARI are reported at the ARI episode level as count (percentage). Missing data of participant characteristics and RSV test results (often due to COVID-19 positivity) were summarised descriptively. SAS statistical software was used to conduct the analyses (V.9.4M7; SAS Institute Cary, North Carolina, USA), and R statistical software was used to generate the figures with ggplot (V.4.2.2; Vienna, Austria). Results Study participants In years 3 and 4 of follow-up, 2511 participants consented or reconsented; however, 11 of them were withdrawn prior to the start of year 3 ARI surveillance (1 October 2021)14 (figure 1 for cohort development). We reported participants as either reconsented or newly consented (online supplemental table 2). The mean age of participants at start of year 3 was 68.2 years (SD 9.3), 60.1% were female, 96.4% identified as non-Hispanic white and 12.9% had diabetes, 10.7% asthma, 6.7% chronic obstructive pulmonary disease and 4.8% congestive heart failure (table 1). The majority (64.6%) of the cohort had received COVID-19 vaccination and 44.6% had received influenza vaccination in the 1 year prior. RSV vaccination started at the end of the fourth non-RSV season with FDA approval in May 2023 and initial Advisory Committee on Immunization Practices recommendation for RSV on 21 June 2023. Only 66 participants were vaccinated (median 11.5 days prior to the end of study period; total 2.37 PY of total follow-up after vaccination across all subjects). Among ARI episodes during years 3 and 4, 574 (25%) were missing RSV status due to lack of RSV swab specimen. The majority (70%) of these ARI episodes without RSV status were positive for COVID-19 which was the reason for not performing the home nasal swab. Download figure Open in new tab Download powerpoint Figure 1 Cohort development. IE refers to inclusion and exclusion. Health decline refers to when participants developed new or worsening health conditions that preventedthem from participating in the study. VIEW INLINE VIEW POPUP Table 1 Sociodemographic at start of year 3 and clinical characteristics by RSV status (analysis set for year 3) Incidence and attack rate of RSV-positive ARI During 2021–2022 following the initial phase of the COVID-19 pandemic in 2020, we found a total of 15 RSV-ARI cases from 2500 participants (attack rate 0.60% (95% CI 0.34 to 0.99)), 14 of which occurred during the RSV season and 1 at the end of the non-RSV season. We found a crude incidence rate of 6.12/1000 PY (95% CI 3.42 to 10.09) and a standardised age-gender-adjusted incidence rate of 6.17 cases/1000 PY (95% CI 2.57 to 9.76). When stratified by age, we found an RSV-ARI incidence rate of 6.84 cases/1000 PY (95% CI 1.41 to 19.98) and an attack rate of 0.67% (95% CI 0.14 to 1.94) in adults aged 50–59 years. In adults aged 60 years and older, there was an RSV-ARI incidence rate of 5.96 cases/1000 PY (95% CI 3.08 to 10.41) and an attack rate during this time was 0.59% (95% CI 0.30 to 1.02). Further stratification by gender showed similar RSV-ARI incidence rates. The majority of the RSV-ARIs were reported as severe because of lower respiratory tract symptoms (table 2). For the incidence of RSV-LRTD, we found an age-gender standardised incidence of 2.79/1000 PY (95% CI 0.05 to 5.53) in year 3 and 8.90/1000 PY (95% CI 4.26 to 13.53) in year 4 (online supplemental table 3). VIEW INLINE VIEW POPUP Table 2 Incidence rate (per 1000 person-years) of first episode of RSV-ARI by age category, gender, RSV subtyping and severity and their attack rates for years 3 and 4 As the omicron COVID-19 pandemic waned, we observed changes in the incidence and attack rates of RSV-ARI during the 2022–2023 compared with the previous season. We found a total of 39 RSV-ARI cases from 2446 participants (attack rate 1.59% (95% CI 1.14 to 2.17)), all occurring during the RSV season. We found a crude incidence rate of 16.40/1000 PY (95% CI 11.66 to 22.42) and a standardised age-gender adjusted incidence rate of 16.99 cases/1000 PY (95% CI 10.63 to 23.35). When stratified by age, we observed RSV-ARI incidence rate of 21.82 cases/1000 PY (95% CI 9.42 to 42.99) and the attack rate of 2.12% (95% CI 0.92 to 4.13) among adults 50–59 years. In participants 60 years and older, we found RSV-ARI incidence rate of 15.41 cases/1000 PY (95% CI 10.47 to 21.88) and the attack rate during this time was 1.50% (95% CI 1.02 to 2.12) with overlapping CIs between the two age groups. There was a difference between gender, with women having an RSV-ARI incidence rate of 22.44 cases/1000 PY (95% CI 15.35 to 31.67) and the attack rate was 2.17% (95% CI 1.49 to 3.05). While in men a lower incidence rate and attack rates were observed: 7.35 cases/1000 PY (95% CI 2.96 to 15.15) and 0.72% (95% CI 0.29 to 1.48), respectively. The predominant RSV subtype was RSV B (92%) for 2021 and RSV A (74%) for 2022 (table 2). There were no coinfections in year 3, while we found 4 of the RSV-ARI in year 4 had coinfection with another virus, including COVID-19, rhinovirus, parainfluenza and OC43 coronavirus. We found a seasonal peak of RSV-ARI in December 2021 for year 3 and November 2022 for year 4 (figure 2). Download figu
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