Respiratory Virus Activity — United States, July 1, 2024–June 30, 2025

Abstract

Respiratory viruses are common causes of upper and lower respiratory tract illness and can also result in hospitalization and death. CDC conducts national surveillance using multiple systems to monitor ongoing and seasonal changes in the activity of selected respiratory viruses. This report summarizes U.S. trends in endemic respiratory virus activity during July 2024–June 2025. For SARS-CoV-2 and respiratory syncytial virus (RSV), national and regional trends; population-based hospitalization rates; vital records death counts; and preliminary estimates of associated illnesses, outpatient visits, hospitalizations, and deaths are described, as well as genetic characterization of circulating SARS-CoV-2 viruses. Some viruses, including SARS-CoV-2, showed bimodal peaks in positive laboratory test results, whereas others, including RSV and influenza viruses, were characterized by a single peak. The highest COVID-19–associated hospitalization rates were reported among adults aged ≥75 years (932.6 per 100,000 persons), infants aged <6 months (285.6), and adults aged 65–74 years (274.4). RSV-associated hospitalization rates were highest among infants aged <12 months (1,116.7 per 100,000; 95% CI = 1,078.4–1,157.9), children aged 12–23 months (770.6; 95% CI = 743.1–800.3), and adults aged ≥75 years (426.9; 95% CI = 366.6–510.8). COVID-19 was associated with an estimated 290,000–450,000 hospitalizations and 34,000–53,000 deaths; RSV was associated with 190,000–350,000 hospitalizations and 10,000–23,000 deaths. All circulating SARS-CoV-2 lineages were Omicron JN.1 descendants. Staying up to date with recommended COVID-19, RSV, and influenza vaccinations remains important to reducing the risk for severe disease caused by these viruses.

Introduction

The circulation of many respiratory viruses, which are common causes of upper and lower respiratory tract illnesses, varies seasonally. Although respiratory viral infections usually cause mild or moderate illnesses, such as the common cold, lower respiratory tract infections can result in hospitalization and death. CDC uses multiple surveillance systems to systematically monitor selected respiratory virus activity in the United States, including SARS-CoV-2 (the virus that causes COVID-19), influenza viruses, respiratory syncytial virus (RSV), human metapneumovirus (hMPV), rhinoviruses and enteroviruses (RV/EV), parainfluenza viruses (PIV) types 1–4, common human coronaviruses (229E, NL63, OC43, and HKU1), and respiratory adenoviruses. This report summarizes U.S. trends in endemic respiratory virus activity during July 2024–June 2025; hospitalization rates, vital records death counts, and estimates of illnesses, outpatient visits, hospitalizations, and deaths for COVID-19 and RSV; and genomic surveillance data for SARS-CoV-2. CDC publishes a separate summary of influenza activity, morbidity, and mortality each season. Ongoing national respiratory virus surveillance is critical for characterizing seasonality, providing information to guide health system preparedness and the timing of prevention product use for certain respiratory viruses, and identifying threats caused by new strains or novel viruses.

Methods

Data Sources

Data from six national surveillance systems (Box) were analyzed for this report. Data on COVID-19 and RSV vaccinations status and COVID-19 antiviral treatment are not systematically collected by some systems and were not analyzed for this report. All findings were limited to data reported during July 1, 2024–June 30, 2025, unless otherwise specified. This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.*

Data Analysis

Respiratory virus activity. The National Respiratory and Enteric Virus Surveillance System (NREVSS) includes results from clinical testing of persons seeking medical care reported by clinical, reference, and public health laboratories throughout the United States. For this report, influenza data were limited to submissions from clinical laboratories and influenza-collaborating laboratories to monitor the timing and intensity of influenza activity. Data from NREVSS were analyzed to provide virus-specific information on percentages of laboratory tests that were positive (percent positive).

Hospitalizations and deaths associated with COVID-19 and RSV. Rates of laboratory-confirmed hospitalization associated with COVID-19 and RSV are monitored by three population-based surveillance systems: 1) the COVID-19–Associated Hospitalization Surveillance Network (COVID-NET), 2) the RSV-Associated Hospitalization Surveillance Network (RSV-NET), and 3) the New Vaccine Surveillance Network (NVSN). COVID-NET and RSV-NET conduct surveillance among residents of all ages in predefined catchment areas to calculate hospitalization rates overall and by age. NVSN conducts surveillance among children and adolescents aged <18 years, with systematic testing of patients with acute respiratory illness at seven U.S. medical centers. Counts of deaths associated with COVID-19 and RSV are described using provisional death certificate data compiled by the National Vital Statistics System (NVSS) based on codes for specific underlying or contributing causes of death.

Modeling estimates. Mathematical models using previously described methods were used to estimate COVID-19 and RSV illnesses, outpatient visits, hospitalizations, and deaths (1). These estimates characterize the impact of these infections on the U.S. population.

SARS-CoV-2 genomic surveillance and RSV subtyping. CDC tracks the genomic evolution of SARS-CoV-2 and estimates variant proportions by integrating sequence data from the National SARS-CoV-2 Strain Surveillance program, public sequence data repositories and, before June 2025, CDC-contracted commercial laboratories. CDC identifies RSV subtype from surveillance specimens received from NVSN and state and local public health laboratories. Data were analyzed using SAS (version 9.4; SAS Institute).

Results

Respiratory Virus Activity

During June 30, 2024–June 28, 2025, bimodal peaks occurred in the percentage of specimens that tested positive for SARS-CoV-2, RV/EV, and PIV 1–4 at laboratories participating in NREVSS (Figure 1). In contrast, single peaks occurred in the percentage of positive laboratory results for RSV, influenza viruses, hMPV, and common coronaviruses.^†

SARS-CoV-2

During the reporting period, 297 laboratories reported 3,961,594 SARS-CoV-2 polymerase chain reaction test results, 260,883 (6.6%) of which were positive. Nationally, the highest percentage of positive SARS-CoV-2 test results (i.e., the peak) (17.9%) occurred during the week ending August 10, 2024 (week 32), and the lowest percentage of positive tests (the trough) (4.0%) occurred during the week ending November 16, 2024 (week 46). A second peak (6.7%) occurred during the week ending January 4, 2025 (week 1) followed by a trough (2.7%) during the week ending May 24, 2025 (week 21). By U.S. Department of Health and Human Services (HHS) region, the peaks within the first elevated period ranged from weeks 29 (HHS Region 9) to 35 (HHS Regions 3 and 5) and within the second elevated period from weeks 48 (HHS Region 6) to 11 (HHS Region 4) (Supplementary Table 1).

Rhinovirus/Enterovirus and Parainfluenza

The two peaks in the percentage of positive RV/EV test results occurred in the fall (30.4%) during the week ending September 21, 2024 (week 38) and the spring (22.3%) during the week ending May 10, 2025 (week 19) (Figure 1). The weekly percentage of positive RV/EV test results ranged from 10.1% to 30.4%. The two peaks in the percentage of positive PIV 1–4 test results occurred in the winter (5.6%) during the week ending November 23, 2024 (week 47) and spring (9.4%) during the week ending May 31, 2025 (week 22).

Respiratory Syncytial Virus

A total of 3,767,034 RSV specimen tests were reported; among these, 178,911 (4.8%) results were positive. The percentage of positive test results peaked at 11.0% during the week ending December 21, 2024 (week 51). Nationally, RSV epidemic onset^§ occurred during the week ending November 9, 2024 (week 45), and epidemic offset occurred during the week ending March 29, 2025 (week 13). Within the continental United States, the earliest RSV epidemic onset occurred in Florida (week 39, ending September 28, 2024), followed by the South (HHS Region 6, week ending October 5, 2024 [week 40]) and the Southeast (HHS Region 4, week ending October 19, 2024 [week 42]); the peak percentage of positive RSV test results also varied by region(Supplementary Table 2).^¶

Influenza, Human Metapneumovirus, and Common Coronavirus

The percentage of positive influenza virus test results from clinical laboratories peaked (31.6%) during the week ending February 1, 2025 (week 5) (Figure 1). The peak in percentage of positive hMPV test results (7.4%) occurred during the week ending April 19, 2025 (week 16). The peak in percentage of positive common coronavirus (types 229E, NL63, OC43, and HKU1) test results (8.3%) occurred during the week ending February 22, 2025 (week 8). A pattern of elevated respiratory adenovirus activity was not observed in the 2024–25 season.

Hospitalizations and Deaths

COVID-19. Based on analysis of COVID-NET data, adults aged ≥75 years experienced the highest rate of COVID-19–associated hospitalization (number of hospitalizations per 100,000 persons) (932.6), followed by infants aged <6 months (285.6), adults aged 65–74 years (274.4) and 50–64 years (104.7), and children aged 6–23 months (104.1) (Figure 2). Pediatric COVID-19–associated hospitalization rates estimated by NVSN were highest among infants aged <6 months (243.0; 95% CI = 174.1–315.2), followed by children aged 6–23 months (92.5; 95% CI = 68.6–120.6).

A total of 34,981 COVID-19–associated deaths were recorded by NVSS, including 187 (0.5%) among children and adolescents aged <18 years, 3,781 (10.8%) among persons aged 18–64 years, and 30,923 (88.4%) among adults aged ≥65 years. During October 1, 2024–July 5, 2025, COVID-19 was associated with an estimated 10.4–16.7 million illnesses, 2.5–4 million outpatient visits, 290,000–450,000 hospitalizations, and 34,000–53,000 deaths.

RSV. RSV-associated hospitalization rates estimated by RSV-NET were highest among infants aged 0–11 months (1,116.7; 95% CI = 1,078.4–1,157.9), followed by children aged 12–23 months (770.6; 95% CI = 743.1–800.3) and adults aged ≥75 years (426.9; 95% CI = 366.6–510.8). Pediatric RSV-associated hospitalization rates estimated by NVSN were highest among infants aged 0–11 months (1,053.9; 95% CI = 949.0–1,159.0), followed by children aged 12–23 months (647.5; 95% CI = 576.7–720.8).

Among 672 RSV-associated deaths recorded by NVSS, 31 (4.6%) occurred among children and adolescents aged <18 years, 89 (13.2%) among adults aged 18–64 years, and 552 (82.1%) among adults aged ≥65 years. During October 1, 2024–May 3, 2025, RSV was associated with an estimated 3.6–6.5 million outpatient visits, 190,000–350,000 hospitalizations, and 10,000–23,000 deaths.

SARS-CoV-2 Lineages and RSV Subtypes

A total of 92,703 SARS-CoV-2 sequences from 56 U.S. jurisdictions were analyzed. Among these, 2% were from the National SARS-CoV-2 Strain Surveillance program, 22% were from commercial laboratories, and 76% were tagged baseline sequences from public repositories. All SARS-CoV-2 lineages circulating at ≥1% prevalence during this period were Omicron JN.1 descendant lineages. During at least one 4-week period, KP.3.1.1-like and LP.8.1 lineages accounted for >50% of sequenced viruses, and KP.2-like, KP.3, LB.1-like, XEC, and XFG lineages accounted for >20% of sequenced viruses (Supplementary Figure). Among 630 RSV specimens from 16 U.S. jurisdictions that had subtyping results, 408 (64.8%) were RSV-A, 204 (32.4%) were RSV-B, and 18 (2.9%) were both RSV-A and RSV-B positive.

Discussion

Since expiration of the COVID-19 pandemic public health emergency declaration in May 2023 (2), CDC has continued efforts to optimize and integrate reporting and communication of national surveillance data for respiratory viruses. This report analyzed data from six complementary national surveillance systems to summarize the 2024–25 season for most respiratory viruses of public health significance.

The bimodal periodicity of positive SARS-CoV-2 test results observed in past years (3) continued during the 2024–25 season, including a larger July peak followed by a smaller January peak. Consistent with recent years preceding the 2024–25 respiratory virus season, COVID-19 hospitalization rates were highest among adults aged ≥75 years, followed by infants aged <6 months who are not eligible for COVID-19 vaccination, and adults aged 65–74 years. Maternal COVID-19 vaccination is the only available immunization strategy to protect infants aged <6 months from severe COVID-19. During 2024–2025, no major SARS-CoV-2 strain replacement occurred; all sequenced SARS-CoV-2 viruses circulating in the United States remained descendants of JN.1. The 2025–26 COVID-19 vaccines are expected to provide protection against severe disease (4–6), including from the XFG variant that approached predominance in late June 2025.**

During 2024–2025, RSV activity followed typical seasonal patterns observed before the COVID-19 pandemic (i.e., increased activity during October–April) that aligned with the timing of RSV vaccination guidance for adults and children for most of the United States. An interim evaluation based on 2024–2025 NVSN and RSV-NET data found that after the introduction of pediatric RSV prevention products, RSV-associated hospitalization rates in infants aged 0–7 months were reduced 28%–43%, compared with seasons preceding the introduction of those products (7). However, during 2024–2025, infants aged 0–11 months still experienced the highest RSV-associated hospitalization rates among all age groups, followed by children aged 12–23 months and adults aged ≥75 years. Three options for protecting infants in their first RSV season against severe RSV disease are available: a maternal RSV vaccine given during pregnancy at 32–36 weeks’ gestation and one of two long-acting monoclonal antibodies (nirsevimab or clesrovimab) administered to infants aged <8 months who are born during or entering their first RSV season (8). A single dose of RSV vaccine is recommended for all adults aged ≥75 years and for adults aged 50–74 years at increased risk for severe RSV disease (9).

Limitations

The findings in this report are subject to at least four limitations. First, NREVSS is a passive and voluntary surveillance system; therefore, data from participating laboratories vary by season and might not be representative of all geographic areas or age groups. Second, because hospitalization rate estimates from NVSN and RSV-NET are generated using different methods and surveillance catchment areas, variations in point estimates, as noted for COVID-19 and RSV hospitalization estimates, are expected. Third, continuing declines in submitted SARS-CoV-2 specimens and resources available for sequencing over time affect the precision of genomic surveillance estimates. Finally, death certificate data likely do not include all deaths from COVID-19 and RSV because not all persons who die after COVID-19 or RSV are tested for these viruses, and some deaths might be attributed to associated complications, such as myocardial infarction or pneumonia. Therefore, deaths from NVSS should be considered minimum counts, whereas CDC estimates of COVID-19 and RSV mortality, which use continuously updated surveillance data, data from the latest scientific reports, and mathematical modeling, account for incomplete data. Because death certificates contain limited information on missed opportunities for intervention and potential risk factors for death, standardized national surveillance and reporting for pediatric laboratory-confirmed COVID-19 and RSV-associated deaths is being implemented in 2026.

Implications for Public Health Practice

Core prevention strategies to reduce the risk for respiratory virus infections include staying up to date with vaccinations, washing hands regularly and cleaning commonly touched surfaces, optimizing ventilation in places where persons live and work, and staying home and away from others when sick. Available antiviral treatments for COVID-19 and influenza are underused (10), despite evidence that they decrease risk for hospitalization and death; early treatment might help decrease the risk for severe illness. CDC continues to monitor respiratory virus activity in the United States and provide weekly updates online.