Human Metapneumovirus Surged in Central China Before Collapsing a Year Later

Human metapneumovirus, a paramyxovirus long overshadowed by influenza and respiratory syncytial virus, staged a dramatic resurgence in central China in late 2024 before its circulation collapsed the following year, according to a large sentinel surveillance study from Henan Province. Researchers at the Henan Provincial Center for Disease Control and Prevention and their collaborators analyzed 36,143 respiratory specimens collected from patients with influenza-like illness or severe acute respiratory infection during 2024 and 2025, screening each sample with multiplex PCR panels covering HMPV and 14 other respiratory pathogens. The results, published in BMC Infectious Diseases, offer one of the most detailed post-pandemic portraits of HMPV epidemiology to date and reveal striking patterns in age distribution, bacterial co-detection, and the temporal choreography between competing respiratory viruses.

The headline finding is a sharp inter-year contrast. Overall HMPV positivity across the two-year surveillance period stood at 3.96 percent, with 1,432 of 36,143 specimens testing positive, but that average conceals two very different years. In 2024, 7.1 percent of tested patients carried the virus; in 2025 the figure fell to just 1.7 percent, a more than fourfold decline. The 2024 epidemic peaked with remarkable intensity: during week 48 of that year, 26.2 percent of all tested respiratory specimens were positive for HMPV, a level few endemic respiratory viruses reach even at the height of a seasonal wave. The authors emphasize that the marked resurgence warrants continued monitoring to determine whether such patterns represent a short-term anomaly or a sustained shift in how HMPV circulates in the region.

Age played a decisive role in who was infected. Children aged 3 to 5 years recorded the highest positivity of any group, at 8.6 percent, corresponding to an enrichment ratio of 2.18 relative to the overall population under surveillance. The concentration became even more extreme during the peak transmission window: supplementary data show that during weeks 48 to 50 of 2024, HMPV positivity among children aged 3 to 5 climbed to 40.7 percent, meaning that roughly two in five young children tested during that brief period carried detectable virus. Preschool children, it appears, were the engine of the 2024 outbreak, a pattern consistent with HMPV’s biology as a virus that spreads efficiently in settings where young children mix closely and have limited accumulated immunity.

Perhaps the most consequential finding concerns what accompanied the virus. Co-infections were detected in 56.2 percent of HMPV-positive cases, and the predominant partners were bacteria rather than other viruses: Streptococcus pneumoniae and Haemophilus influenzae were the most frequently co-detected organisms. Both are common colonizers of the human nasopharynx that can turn pathogenic when viral infection disrupts mucosal defenses, and their frequent co-detection with HMPV raises questions about the contribution of bacterial carriage to disease severity in pediatric respiratory illness. The study’s statistical framework went beyond simple co-detection rates, quantifying pathogen associations through odds ratios that distinguish genuine ecological interaction from chance overlap in a busy respiratory season.

Those odds ratios paint a picture of competitive and facilitative relationships within the respiratory microbiome. HMPV showed a positive association with Streptococcus pneumoniae, with an odds ratio of 2.01, and a weaker positive association with Haemophilus influenzae, at 1.47. Human bocavirus, a virus whose clinical significance remains debated, also tracked positively with HMPV at an odds ratio of 1.66. In contrast, the relationships with the two major winter respiratory viruses were strongly negative: HMPV was negatively associated with influenza virus (odds ratio 0.20) and with respiratory syncytial virus (odds ratio 0.17). Such inverse associations suggest that these viruses do not simply peak independently; each appears to suppress or be suppressed by the others, whether through interference at the host level, depletion of susceptible individuals, or behavioral and environmental factors that favor one agent at a time.

The temporal analysis added a dynamic dimension to these static associations. Using cross-correlation and regression techniques on weekly surveillance data, the researchers found that respiratory syncytial virus positivity at a one-week lag had a positive effect on subsequent HMPV positivity, with a regression coefficient of 0.15 that reached statistical significance at P equals 0.048. In practical terms, an RSV wave in a given week slightly preceded and predicted a rise in HMPV detections the following week. This lead-lag relationship is intriguing because it coexists with the overall negative association between the two viruses across the full dataset, hinting at a nuanced interaction in which one virus may briefly facilitate conditions for another before competition or immunity-driven exclusion takes over across the longer arc of the season.

Methodologically, the study illustrates the value of dense, multiplexed sentinel surveillance. By testing every specimen against 15 pathogens simultaneously, the team could compute enrichment ratios identifying which age groups disproportionately contributed to transmission, pairwise odds ratios revealing pathogen associations, and time-series models capturing the ordering of epidemic waves. The distinction between influenza-like illness and severe acute respiratory infection cases in the sentinel framework also matters, because viruses and co-pathogens may distribute differently across the spectrum of severity. Findings of this kind are difficult to obtain from clinical testing alone, which is typically biased toward severely ill patients and ordered on an ad hoc basis rather than systematically.

The public health implications are twofold. First, the high rate of bacterial co-detection argues for integrated surveillance that monitors respiratory bacteria alongside viruses, since pneumococcus and Haemophilus influenzae are both vaccine-preventable in their major serotypes, and their co-circulation with HMPV may shape the clinical burden of an HMPV season. Second, the temporal lead-lag relationship with RSV underscores the authors’ call for integrated pathogen surveillance: signals from one virus’s epidemic curve may serve as early indicators for another, improving the timeliness of clinical preparedness in pediatrics. The strong concentration of cases among children aged 3 to 5 further supports age-targeted prevention strategies, whether through caregiver hygiene measures, cohorting in preschool settings, or, eventually, vaccines and monoclonal approaches now in development for HMPV, which currently has no licensed specific countermeasure.

Open questions remain. Henan, a province of nearly 100 million people in central China, provides a robust but geographically specific vantage point, and whether the 2024 surge reflects an immunity debt accrued during pandemic-era contact reductions, viral evolutionary change, or ordinary multi-year epidemic cycling cannot be resolved from two seasons of data. The steep drop in 2025, to 1.7 percent positivity, could indicate that the susceptible pool was largely replenished and depleted within a single intense season, resetting the epidemic clock. The authors themselves frame the 2024 resurgence as a phenomenon requiring continued monitoring, and further seasons of sentinel data will be needed to determine whether HMPV in the region settles into a predictable alternation with RSV and influenza or follows a new post-pandemic rhythm. For now, the study stands as a detailed empirical record of an HMPV outbreak at its peak, capturing a virus that can, in a matter of weeks, infect more than a quarter of young children presenting with acute respiratory illness before receding almost entirely from view.

Subject of Research: Epidemiology and co-infection patterns of human metapneumovirus in central China, 2024–2025

Article Title: Human metapneumovirus in central China, 2024–2025: epidemiology, co-infections, and temporal dynamics

Article References: Yonghao, G., Qian, L., Baolong, D., Minghua, S., Sheng, Z., Jiangnan, K., Qiaohua, D., Wenhui, W., Daxing, F., Wanyu, L., Jianhui, Y., Xiaoyang, W., Xiaoxiao, Z., Yuling, Z., Huixin, L., Kaiqin, T., Yanyang, Z., & Dongyang, Z. (2026). Human metapneumovirus in central China, 2024–2025: epidemiology, co-infections, and temporal dynamics. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14477-y

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14477-y

Keywords: human metapneumovirus, HMPV, respiratory syncytial virus, co-infection, sentinel surveillance, Streptococcus pneumoniae, Haemophilus influenzae, pediatric respiratory infection, Henan China, epidemiology, multiplex PCR, seasonal respiratory viruses