3 research outputs found
Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis.
BACKGROUND: Influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus are the most common viruses associated with acute lower respiratory infections in young children (<5 years) and older people (≥65 years). A global report of the monthly activity of these viruses is needed to inform public health strategies and programmes for their control.
METHODS: In this systematic analysis, we compiled data from a systematic literature review of studies published between Jan 1, 2000, and Dec 31, 2017; online datasets; and unpublished research data. Studies were eligible for inclusion if they reported laboratory-confirmed incidence data of human infection of influenza virus, respiratory syncytial virus, parainfluenza virus, or metapneumovirus, or a combination of these, for at least 12 consecutive months (or 52 weeks equivalent); stable testing practice throughout all years reported; virus results among residents in well-defined geographical locations; and aggregated virus results at least on a monthly basis. Data were extracted through a three-stage process, from which we calculated monthly annual average percentage (AAP) as the relative strength of virus activity. We defined duration of epidemics as the minimum number of months to account for 75% of annual positive samples, with each component month defined as an epidemic month. Furthermore, we modelled monthly AAP of influenza virus and respiratory syncytial virus using site-specific temperature and relative humidity for the prediction of local average epidemic months. We also predicted global epidemic months of influenza virus and respiratory syncytial virus on a 5° by 5° grid. The systematic review in this study is registered with PROSPERO, number CRD42018091628.
FINDINGS: We initally identified 37 335 eligible studies. Of 21 065 studies remaining after exclusion of duplicates, 1081 full-text articles were assessed for eligibility, of which 185 were identified as eligible. We included 246 sites for influenza virus, 183 sites for respiratory syncytial virus, 83 sites for parainfluenza virus, and 65 sites for metapneumovirus. Influenza virus had clear seasonal epidemics in winter months in most temperate sites but timing of epidemics was more variable and less seasonal with decreasing distance from the equator. Unlike influenza virus, respiratory syncytial virus had clear seasonal epidemics in both temperate and tropical regions, starting in late summer months in the tropics of each hemisphere, reaching most temperate sites in winter months. In most temperate sites, influenza virus epidemics occurred later than respiratory syncytial virus (by 0·3 months [95% CI -0·3 to 0·9]) while no clear temporal order was observed in the tropics. Parainfluenza virus epidemics were found mostly in spring and early summer months in each hemisphere. Metapneumovirus epidemics occurred in late winter and spring in most temperate sites but the timing of epidemics was more diverse in the tropics. Influenza virus epidemics had shorter duration (3·8 months [3·6 to 4·0]) in temperate sites and longer duration (5·2 months [4·9 to 5·5]) in the tropics. Duration of epidemics was similar across all sites for respiratory syncytial virus (4·6 months [4·3 to 4·8]), as it was for metapneumovirus (4·8 months [4·4 to 5·1]). By comparison, parainfluenza virus had longer duration of epidemics (6·3 months [6·0 to 6·7]). Our model had good predictability in the average epidemic months of influenza virus in temperate regions and respiratory syncytial virus in both temperate and tropical regions. Through leave-one-out cross validation, the overall prediction error in the onset of epidemics was within 1 month (influenza virus -0·2 months [-0·6 to 0·1]; respiratory syncytial virus 0·1 months [-0·2 to 0·4]).
INTERPRETATION: This study is the first to provide global representations of month-by-month activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus. Our model is helpful in predicting the local onset month of influenza virus and respiratory syncytial virus epidemics. The seasonality information has important implications for health services planning, the timing of respiratory syncytial virus passive prophylaxis, and the strategy of influenza virus and future respiratory syncytial virus vaccination.
FUNDING: European Union Innovative Medicines Initiative Respiratory Syncytial Virus Consortium in Europe (RESCEU).</p
Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis
Background: Influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus are the most
common viruses associated with acute lower respiratory infections in young children (<5 years) and older people
(≥65 years). A global report of the monthly activity of these viruses is needed to inform public health strategies and
programmes for their control.
Methods: In this systematic analysis, we compiled data from a systematic literature review of studies published between
Jan 1, 2000, and Dec 31, 2017; online datasets; and unpublished research data. Studies were eligible for inclusion if they
reported laboratory-confirmed incidence data of human infection of influenza virus, respiratory syncytial virus,
parainfluenza virus, or metapneumovirus, or a combination of these, for at least 12 consecutive months (or 52 weeks
equivalent); stable testing practice throughout all years reported; virus results among residents in well-defined
geographical locations; and aggregated virus results at least on a monthly basis. Data were extracted through a threestage process, from which we calculated monthly annual average percentage (AAP) as the relative strength of virus
activity. We defined duration of epidemics as the minimum number of months to account for 75% of annual positive
samples, with each component month defined as an epidemic month. Furthermore, we modelled monthly AAP of
influenza virus and respiratory syncytial virus using site-specific temperature and relative humidity for the prediction of
local average epidemic months. We also predicted global epidemic months of influenza virus and respiratory syncytial
virus on a 5° by 5° grid. The systematic review in this study is registered with PROSPERO, number CRD42018091628.
Findings: We initally identified 37 335 eligible studies. Of 21 065 studies remaining after exclusion of duplicates,
1081 full-text articles were assessed for eligibility, of which 185 were identified as eligible. We included 246 sites for
influenza virus, 183 sites for respiratory syncytial virus, 83 sites for parainfluenza virus, and 65 sites for
metapneumovirus. Influenza virus had clear seasonal epidemics in winter months in most temperate sites but
timing of epidemics was more variable and less seasonal with decreasing distance from the equator. Unlike influenza
virus, respiratory syncytial virus had clear seasonal epidemics in both temperate and tropical regions, starting in late
summer months in the tropics of each hemisphere, reaching most temperate sites in winter months. In most
temperate sites, influenza virus epidemics occurred later than respiratory syncytial virus (by 0·3 months [95% CI
–0·3 to 0·9]) while no clear temporal order was observed in the tropics. Parainfluenza virus epidemics were found
mostly in spring and early summer months in each hemisphere. Metapneumovirus epidemics occurred in late
winter and spring in most temperate sites but the timing of epidemics was more diverse in the tropics. Influenza
virus epidemics had shorter duration (3·8 months [3·6 to 4·0]) in temperate sites and longer duration (5·2 months
[4·9 to 5·5]) in the tropics. Duration of epidemics was similar across all sites for respiratory syncytial virus
(4·6 months [4·3 to 4·8]), as it was for metapneumovirus (4·8 months [4·4 to 5·1]). By comparison, parainfluenza
virus had longer duration of epidemics (6·3 months [6·0 to 6·7]). Our model had good predictability in the average
epidemic months of influenza virus in temperate regions and respiratory syncytial virus in both temperate and
tropical regions. Through leave-one-out cross validation, the overall prediction error in the onset of epidemics was
within 1 month (influenza virus −0·2 months [−0·6 to 0·1]; respiratory syncytial virus 0·1 months [−0·2 to 0·4]).
Interpretation: This study is the first to provide global representations of month-by-month activity of influenza virus,
respiratory syncytial virus, parainfluenza virus, and metapneumovirus. Our model is helpful in predicting the local
onset month of influenza virus and respiratory syncytial virus epidemics. The seasonality information has important
implications for health services planning, the timing of respiratory syncytial virus passive prophylaxis, and the
strategy of influenza virus and future respiratory syncytial virus vaccination
Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in young children in 2015: a systematic review and modelling study
BACKGROUND: We have previously estimated that respiratory
syncytial virus (RSV) was associated with 22% of all episodes of
(severe) acute lower respiratory infection (ALRI) resulting in
55 000 to 199 000 deaths in children younger than 5 years in
2005. In the past 5 years, major research activity on RSV has
yielded substantial new data from developing countries. With a
considerably expanded dataset from a large international
collaboration, we aimed to estimate the global incidence,
hospital admission rate, and mortality from RSV-ALRI episodes in
young children in 2015. METHODS: We estimated the incidence and
hospital admission rate of RSV-associated ALRI (RSV-ALRI) in
children younger than 5 years stratified by age and World Bank
income regions from a systematic review of studies published
between Jan 1, 1995, and Dec 31, 2016, and unpublished data from
76 high quality population-based studies. We estimated the
RSV-ALRI incidence for 132 developing countries using a risk
factor-based model and 2015 population estimates. We estimated
the in-hospital RSV-ALRI mortality by combining in-hospital case
fatality ratios with hospital admission estimates from
hospital-based (published and unpublished) studies. We also
estimated overall RSV-ALRI mortality by identifying studies
reporting monthly data for ALRI mortality in the community and
RSV activity. FINDINGS: We estimated that globally in 2015, 33.1
million (uncertainty range [UR] 21.6-50.3) episodes of RSV-ALRI,
resulted in about 3.2 million (2.7-3.8) hospital admissions, and
59 600 (48 000-74 500) in-hospital deaths in children younger
than 5 years. In children younger than 6 months, 1.4 million (UR
1.2-1.7) hospital admissions, and 27 300 (UR 20 700-36 200)
in-hospital deaths were due to RSV-ALRI. We also estimated that
the overall RSV-ALRI mortality could be as high as 118 200 (UR
94 600-149 400). Incidence and mortality varied substantially
from year to year in any given population. INTERPRETATION:
Globally, RSV is a common cause of childhood ALRI and a major
cause of hospital admissions in young children, resulting in a
substantial burden on health-care services. About 45% of
hospital admissions and in-hospital deaths due to RSV-ALRI occur
in children younger than 6 months. An effective maternal RSV
vaccine or monoclonal antibody could have a substantial effect
on disease burden in this age group. FUNDING: The Bill &
Melinda Gates Foundation