(A-348) Incidence of human metapneumovirus among older adults in 10 high-income countries: a systematic literature review, meta-analysis, and modeling study

Background: Human metapneumovirus (hMPV), a respiratory pathogen identified in 2001, plays a significant role in respiratory illnesses with seasonal outbreaks affecting individuals of all ages. While hMPV is increasingly recognized, the epidemiologic landscape for this virus is poorly characterized, particularly among older adults. Estimating the burden of hMPV may help inform vaccine development efforts.

Objectives: To generate modelled estimates of the age-, sex-, and location-specific incidence of hMPV among older adults in the general population in 10 high-income locations (Canada, Chile, France, Germany, New Zealand, Netherlands, Italy, Spain, United Kingdom [UK], and United States [US]).

Methods: A systematic literature review (PROSPERO registration CRD42023441008) was conducted to identify sources informing the share of lower respiratory infection (LRI) episodes due to hMPV, and the findings from these sources were meta-analyzed to generate an estimate of the share of LRI episodes due to hMPV. We then quantified the incidence of LRI with hMPV in the 10 select countries among older adults in the most recent pre-pandemic year, 2019, by leveraging the latest estimates of LRI incidence from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD 2021), and meta-analyzed findings from the systematic literature review.

Results: The systematic literature review identified 21 studies with data on the percentage of LRI episodes associated with hMPV in adults aged 60+ years in the targeted locations. Combining the meta-analyzed percentage of LRI cases associated with hMPV from these studies (7.0%; 95% confidence interval: 5.4, 9.1) with age-, sex-, and location-specific estimates of LRI incidence from GBD 2021 Study, we estimated hMPV incidence rates per 100,000 in 2019 among adults aged 60+: 462.1 (95% uncertainty interval: 333.1, 628.2) in the US, 404.8 (295.3, 543.6) in Canada, 382.5 (278.5, 518.8) in the UK, 315.7 (227.0, 424.0) in Chile, 254.7 (183.2, 343.8) in New Zealand, 226.9 (161.6, 304.3) in Spain, 215.3 (156.1, 289.7) in France, 212.4 (153.5, 283.4) in Germany, 191.7 (139.5, 259.5) in Netherlands, 185.7 (134.7, 251.1) in Italy.

Conclusions: Overall, our literature review, meta-analysis, and modeling study confirm a significant burden of hMPV-associated LRI in older adults. This work fills a critical evidence gap in the epidemiological landscape of hMPV and yields actionable estimates to inform vaccine development strategies and other strategic initiatives. Future inclusion of hMPV in routine surveillance would enable more comprehensive estimates of hMPV incidence and outcomes.