Age‐Related Asymptomatic Rhinovirus Infections Contribute to the Sustained Prevalence in Adults and Are Not Mitigated by Nonpharmaceutical Interventions

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  FIGURE 1. The inclusion process for asymptomatic and symptomatic rhinovirus infected subjects during two study periods.

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  FIGURE 2. The prevalence of rhinovirus in distinct age groups showed significant differences. No matter the total RV infection age distribution (A) or during certain study period such as 2021–2022 (B) or 2023–2024 (C), RV‐A asymptomatic infections showed the most significant age difference. (D) The asymptomatic infection rate in the 18–59 age group was significantly higher than in those over 60. (E) No significant difference in adult asymptomatic RV infection rates between the period of strict nonpharmaceutical interventions (NPIs) (2021–2022) and the period without NPIs (2023–2024).

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  FIGURE 3. The number of RV detection (A) and species distribution (B) among the four clinical groups over the 2‐year study period. (A) During March 2021 to February 2022, peak asymptomatic RV infection rates were observed from March to July, while peak symptomatic RV infection rates occurred from May to July and October to December. During June 2023 to May 2024, peak RV infection rates among asymptomatic and symptomatic subjects occurred in November to December and October, respectively. (B) RV‐A was prevalent year‐round, whereas RV‐C was mainly concentrated in autumn and winter, particularly among symptomatic individuals. RV‐B predominantly caused asymptomatic infections in autumn and winter.

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  FIGURE 4. (A) Seasonality of rhinovirus (RV) infections and meteorological profiles in Shanghai during March 2021 to February 2022 and June 2023 to May 2024. (B) Bar and line charts illustrating the trends between RV incidence and meteorological factors are depicted. Statistical analysis revealed a significant negative correlation between infection rates and monthly rainfall for asymptomatic infections (r = −0.418, p = 0.042), whereas temperature and relative humidity showed no significant correlation. Rainfall exhibited significant positive correlations with both temperature (r = 0.780, p < 0.0001) and relative humidity (r = 0.789, p < 0.0001).

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  FIGURE 5. Rhinovirus (RV) detection rate and species distribution according to month of detection.

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  FIGURE 6. (A) Symptomatic RV‐C infections exhibited significantly higher viral loads compared to asymptomatic cases. In contrast, RV‐A and RV‐B infections showed no significant differences in viral loads between symptomatic and asymptomatic individuals. (B) Asymptomatic RV‐A infections generally exhibited higher viral loads among individuals aged 18–59. (C) Symptomatic RV‐C infections in individuals aged over 60 had significantly higher viral loads compared to asymptomatic cases.

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  FIGURE 7. Symptomatic RV infections were significantly associated with higher rates of co‐infections or secondary infections with other respiratory viruses compared to asymptomatic cases. The incidence of co‐infections or secondary infections was significantly higher during 2023–2024 compared to 2021–2022.