IMPORTANCE: Asymptomatic infections are potential sources of transmission for COVID-19. OBJECTIVE: To evaluate the percentage of asymptomatic infections among individuals undergoing testing (tested ...population) and those with confirmed COVID-19 (confirmed population). DATA SOURCES: PubMed, EMBASE, and ScienceDirect were searched on February 4, 2021. STUDY SELECTION: Cross-sectional studies, cohort studies, case series studies, and case series on transmission reporting the number of asymptomatic infections among the tested and confirmed COVID-19 populations that were published in Chinese or English were included. DATA EXTRACTION AND SYNTHESIS: This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Random-effects models were used to estimate the pooled percentage and its 95% CI. Three researchers performed the data extraction independently. MAIN OUTCOMES AND MEASURES: The percentage of asymptomatic infections among the tested and confirmed populations. RESULTS: Ninety-five unique eligible studies were included, covering 29 776 306 individuals undergoing testing. The pooled percentage of asymptomatic infections among the tested population was 0.25% (95% CI, 0.23%-0.27%), which was higher in nursing home residents or staff (4.52% 95% CI, 4.15%-4.89%), air or cruise travelers (2.02% 95% CI, 1.66%-2.38%), and pregnant women (2.34% 95% CI, 1.89%-2.78%). The pooled percentage of asymptomatic infections among the confirmed population was 40.50% (95% CI, 33.50%-47.50%), which was higher in pregnant women (54.11% 95% CI, 39.16%-69.05%), air or cruise travelers (52.91% 95% CI, 36.08%-69.73%), and nursing home residents or staff (47.53% 95% CI, 36.36%-58.70%). CONCLUSIONS AND RELEVANCE: In this meta-analysis of the percentage of asymptomatic SARS-CoV-2 infections among populations tested for and with confirmed COVID-19, the pooled percentage of asymptomatic infections was 0.25% among the tested population and 40.50% among the confirmed population. The high percentage of asymptomatic infections highlights the potential transmission risk of asymptomatic infections in communities.
ObjectiveHepatitis B virus (HBV) infection is a major public health problem worldwide. Several studies have reported that ABO blood groups may be associated with HBV infection. However, its ...association is still controversial. We performed a meta-analysis to investigate whether ABO blood groups were associated with HBV infection.DesignSystematic review and meta-analysis.Data sourcesRelevant studies available before 1 December 2019 were identified by searching PubMed, EMBASE, Web of Science, ScienceDirect and the Cochrane Library.Eligibility criteriaAll cross-sectional or cohort studies from which the data of ABO blood group distribution and HBV infection could be extracted.Data extraction and synthesisStudies were identified and extracted by two reviewers independently. Risk ratios (RRs) and 95% CIs were pooled by random-effect models to quantify this association.ResultsThirty-eight eligible articles including 241 868 HBV-infected subjects and 6 487 481 uninfected subjects were included. Overall, the risk of HBV infection had decreased by 8% in subjects with blood group B when compared with non-B blood group (RR=0.92, 95% CI 0.86 to 0.98). In the subgroup analyses, the inverse relationship between blood group B and HBV infection remained stable in higher endemic areas (HBV prevalence ≥5%), Asian people, larger sample size studies (≥2000), general population and blood donors, lower middle income group and studies published before the year 2010. Additionally, subjects with blood group O had a 12% increased risk of HBV infection (RR=1.12, 95% CI 1.01 to 1.24) in higher endemic areas. In the sensitivity analysis, the pooled risk estimates of blood group B and HBV infection were still stable.ConclusionsOur data suggested that the blood group B was associated with a lower risk of HBV infection. More research is needed to clarify the precise role of the ABO blood group in HBV infection to address the global question of HBV infection.
The coronavirus disease 2019 (COVID-19) pandemic is the defining global health crisis of our time and the greatest challenge facing the world. Meteorological parameters are reportedly crucial factors ...affecting respiratory infectious disease epidemics; however, the effect of meteorological parameters on COVID-19 remains controversial. This study investigated the effects of temperature and relative humidity on daily new cases and daily new deaths of COVID-19, which has useful implications for policymakers and the public. Daily data on meteorological conditions, new cases and new deaths of COVID-19 were collected for 166 countries (excluding China) as of March 27, 2020. Log-linear generalized additive model was used to analyze the effects of temperature and relative humidity on daily new cases and daily new deaths of COVID-19, with potential confounders controlled for, including wind speed, median age of the national population, Global Health Security Index, Human Development Index and population density. Our findings revealed that temperature and relative humidity were both negatively related to daily new cases and deaths. A 1 °C increase in temperature was associated with a 3.08% (95% CI: 1.53%, 4.63%) reduction in daily new cases and a 1.19% (95% CI: 0.44%, 1.95%) reduction in daily new deaths, whereas a 1% increase in relative humidity was associated with a 0.85% (95% CI: 0.51%, 1.19%) reduction in daily new cases and a 0.51% (95% CI: 0.34%, 0.67%) reduction in daily new deaths. The results remained robust when different lag structures and the sensitivity analysis were used. These findings provide preliminary evidence that the COVID-19 pandemic may be partially suppressed with temperature and humidity increases. However, active measures must be taken to control the source of infection, block transmission and prevent further spread of COVID-19.
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•First study to explore the effects of temperature and humidity on the daily new cases and deaths of COVID-19 worldwide.•We used log-linear GAM to analyze the effects.•We considered the lag effects and the cumulative effects of weather conditions.•Temperature and relative humidity were both negatively related to the daily new cases and daily new deaths of COVID-19
Lower respiratory infections (LRIs) are a leading cause of death worldwide. We aimed to estimate the trends of global and regional aetiologies, risk factors and mortality of LRIs from 1990 to 2019.
...From the Global Burden of Disease (GBD) Study 2019, we collected relevant data, including annual LRI deaths, mortality and deaths and mortality attributable to the four high-burden aetiologies and 14 risk factors during 1990-2019. To quantify the temporal trends, estimated annual percentage changes (EAPCs) were calculated by fitting linear regression model.
Globally, the age-standardized mortality due to LRIs decreased by an average of 2.39% (95% CI 2.33%-2.45%) per year, from 66.67 deaths per 100,000 in 1990 to 35.72 deaths per 100,000 in 2019. Low Socio-demographic Index regions, South Asia and Sub-Saharan Africa had the heaviest burden of LRIs. The age-standardized mortality decreased in 18 GBD regions, whereas increased in Southern Latin America (EAPC = 1.20, 95% CI 1.03-1.37). LRIs led to considerable deaths among children under 5 years and adults older than 70 years. Streptococcus pneumoniae was the first leading aetiology, accounting for over 50% of LRI deaths. Household air pollution from solid fuels, child wasting and ambient particulate matter pollution were the three leading risk factors for LRI mortality in 2019.
LRIs remain an important health problem globally, especially in some vulnerable areas and among children under 5 and adults over 70 years. Future researches focusing on the aetiologies and risk factors for LRIs are needed to provide targeted and updated prevention strategies.
Background/Aims
Hepatitis E virus (HEV) infection is an important cause of acute viral hepatitis worldwide, but it is long‐neglected. We aimed to understand the global trends and regional differences ...in the incidence of HEV infection, thereby making global tailored prevention strategies.
Methods
This study is a post‐hoc analysis of the data from Global Burden of Disease Study 2017. Annual HEV incident cases and incidence rates from 1990 to 2017 were collected. Changes in incident cases and estimated annual percentage changes (EAPCs) of age‐standardized incidence rates (ASRs) were calculated to quantify the temporal trends of HEV infection.
Results
Globally, HEV ASRs decreased by an average 0.16% (95% CI: 0.14%‐0.17%) per year from 279.79 per 100 000 in 1990 to 269.70 per 100 000 in 2017; however, the number of HEV incident cases increased by 17.63% from 16.53 million in 1990 to 19.44 million in 2017. Against the global trend of ASR falling, an increasing trend was reported in Oceania (EAPC = 0.03; 95% CI: 0.03‐0.04) and Western Europe (EAPC = 0.02; 95% CI: 0.01‐0.03). The number of HEV incident cases increased remarkably in low (63.07%) and low‐middle (37.46%) Socio‐Demographic Index (SDI) regions between 1990 and 2017. Additionally, the number of HEV incident cases increased by 4.63% in high SDI regions, mainly in 40 plus age group. Surprisingly, more than 40% of HEV incident cases in Western Europe in 2017 were over 40 years old.
Conclusions
HEV is still pending in hyperendemic regions, and it is emerging in low endemic regions, suggesting more efforts should be done to make targeted prevention strategies.
By 31 December 2020, Coronavirus disease 2019 (COVID-19) had been prevalent worldwide for one year, and most countries had experienced a complete seasonal cycle. The role of the climate and ...environment are essential factors to consider in transmission.
We explored the association between global meteorological conditions (including mean temperature, wind speed, relative humidity and diurnal temperature range) and new cases of COVID-19 in the whole past year. We assessed the relative risk of meteorological factors to the onset of COVID-19 by using generalized additive models (GAM) and further analyzed the hysteresis effects of meteorological factors using the Distributed Lag Nonlinear Model (DLNM).
Our findings revealed that the mean temperature, wind speed and relative humidity were negatively correlated with daily new cases of COVID-19, and the diurnal temperature range was positively correlated with daily new cases of COVID-19. These relationships were more apparent when the temperature and relative humidity were lower than their average value (21.07°Cand 66.83%). The wind speed and diurnal temperature range were higher than the average value(3.07 m/s and 9.53 °C). The maximum RR of mean temperature was 1.30 under −23°C at lag ten days, the minimum RR of wind speed was 0.29 under 12m/s at lag 24 days, the maximum RR of range of temperature was 2.21 under 28 °C at lag 24 days, the maximum RR of relative humidity was 1.35 under 4% at lag 0 days. After a subgroup analysis of the countries included in the study, the results were still robust.
As the Northern Hemisphere enters winter, the risk of global covid-19 remains high. Some countries have ushered in a new round of COVID-19 epidemic. Thus, active measures must be taken to control the source of infection, block transmission and prevent further spread of COVID-19 in winter.
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•We used time series analysis to study the relationship between meteorological factors and the transmission of COVID-19.•Global prevalence figures of COVID-19 and meteorological data for a whole year were analyzed.•We use a distributed lag linear model to study the lag effect of meteorological factors on the incidence of COVID-19.
Background and purpose
Despite decades of improved sanitation and hygiene measures and vaccine introduction, hepatitis A has been spread through numerous outbreaks globally. We used data from the ...Global Burden of Disease (GBD) study to quantify hepatitis A burden at the global, regional and national levels.
Methods
Annual incident cases, deaths, age-standardized incidence rates (ASIRs), and age-standardized mortality rates (ASMRs) of hepatitis A between 1990 and 2019 were derived from the GBD study 2019. Percentage changes of cases and deaths, and estimated annual percentage changes (EAPCs) of ASIRs and ASMRs were calculated to quantify their temporal trends.
Results
Global hepatitis A incident cases increased by 13.90% from 139.54 million in 1990 to 158.94 million in 2019. ASIR of hepatitis A remained stable (EAPC = 0.00, 95% CI −0.01 to 0.01), whereas ASMR decreased (EAPC = −4.63, 95% CI −4.94 to −4.32) between 1990 and 2019. ASIR increased in low (EAPC = 0.09, 95% CI 0.04 to 0.14) and low-middle (EAPC = 0.04, 95% CI 0.03 to 0.06) socio-demographic index (SDI) regions. For GBD regions, the most significant increases of ASIR were detected in high-income Asia Pacific (EAPC = 0.53, 95% CI 0.41 to 0.66), Oceania (EAPC = 0.31, 95% CI 0.25 to 0.36), and Australasia (EAPC = 0.28, 95% CI 0.13 to 0.44). EAPC of ASIR was positively associated with SDI value in countries and territories with SDI value ≥ 0.7 (
ρ
= −0.310,
p
< 0.001).
Conclusion
There is an unfavorable trend that hepatitis A is still pending in hyperendemic regions and is emerging in low endemic regions. These highlight the need of targeted and specific strategies to eliminate hepatitis A, such as sanitation measures and a comprehensive plan for surveillance and vaccination against hepatitis A.
Abstract
Background
Malaria is a life-threatening disease worldwide, but lacks studies on its incidence at the global level. We aimed to describe global trends and regional diversities in incidence ...of malaria infection, to make global tailored implications for malaria prevention.
Methods
We used the data from the Global Burden of Disease Study 2019. The age-standardized incidence rate (ASR) and absolute number of malaria episodes showed the epidemic status of malaria infection. The estimated annual percentage change of ASR and changes in malaria episodes quantified the malaria incidence trends. The connection between ASRs and traveller number indicated infection risk for travellers.
Results
Globally, the malaria ASR decreased by an average 0.80% (95% confidence interval 0.58–1.02%) per year from 1990 to 2019; however, it slightly increased from 3195.32 per 100 000 in 2015 to 3247.02 per 100 000 in 2019. The incidence rate of children under 5 was higher than other age groups. A total of 40 countries had higher ASRs in 2019 than in 2015, with the largest expansion in Cabo Verde (from 2.02 per 100 000 to 597.00 per 100 000). After 2015, the ASRs in high-middle, middle and low-middle Socio-demographic Index regions began to rise and the uptrends remained in 2019. Central, Western and Eastern Sub-Saharan Africa had the highest ASRs since 1990, and traveller number in Eastern and Western Sub-Saharan Africa increased by 31.24 and 7.58%, respectively, from 2017 to 2018. Especially, most countries with ASR over 10 000 per 100 000 had increase in traveller number from 2017 to 2018, with the highest change by 89.56% in Mozambique.
Conclusions
Malaria is still a public health threat for locals and travellers in Sub-Saharan Africa and other malaria-endemic areas, especially for children under 5. There were unexpected global uptrends of malaria ASRs from 2015 to 2019. More studies are needed to achieve the goal of malaria elimination.
Background Zika virus (ZIKV) infection has potential result in severe birth effects. An improved understanding of global trend and regional differences is needed. Methods Annual ZIKV infection ...episodes and incidence rates were collected from Global Burden of Disease Study 2019. Episodes changes and estimated annual percentage changes (EAPCs) of age-standardized incidence rate (ASR) were calculated. Top passenger airport-pairs were obtained from the International Air Transport Association to understand places susceptible to imported ZIKV cases. Results Globally, the ASR increased by an average of 72.85% (95%CI: 16.47% to 156.53%) per year from 2011 to 2015 and subsequently decreased from 20.25 per 100,000 in 2015 to 3.44 per 100,000 in 2019. Most of ZIKV infections clustered in Latin America. The proportion of episodes in Central and Tropical Latin America decreased in 2019 with sporadic episodes elsewhere. High Socio-Demographic Index (SDI) regions had more episodes in 2019 than in 2015. Additionally, 15-49 years group had the largest proportion of episodes, females had a higher number of episodes, and a higher incidence rate of 70 plus group was observed in males than females. Certain cities in Europe, North America and Latin America/Caribbean had a high population mobility in ZIKV outbreak areas considered a high risk of imported cases. Conclusions ZIKV infection is still a public health threat in Latin America and Caribbean and high SDI regions suffered an increasing trend of ZIKV infection. Interventions such as development of surveillance networks and vector-control should be attached to ZIKV control in these key regions. Reproductive suggestions should be taken to reduce ZIKV-related birth defects for the people of reproductive age who are facing a higher threat of ZIKV infection, especially females. Moreover, surveillance of travellers is needed to reverse the uptrends of travel-related imported ZIKV infection. More studies focusing on ZIKV should be performed to make targeted and effective prevention strategies in the future.
China has the world's largest burden of hepatitis B virus (HBV) infection, but the country has made considerable progress in preventing its mother-to-child transmission (MTCT) in the past three ...decades. This feat is made possible due to the high coverage of birth-dose hepatitis B vaccine (HepB,>95%), hepatitis B surface antigen (HBsAg) screening for pregnant women (>99%), and hepatitis B immunoglobulin plus HepB for newborns whose mothers are HBsAg positive (>99%). Studies on the optimal antiviral treatment regimen for pregnant women with high HBV-DNA load have also been conducted. However, China still faces challenges in eliminating MTCT of HBV. The overall HBsAg prevalence among pregnant women is considered an intermediate endemic. The prevalence of HBsAg among pregnant women from remote, rural, or ethnic minority areas is higher than that of the national level because of limited health resources and public health education for HBV. The coverage for maternal and child healthcare and immunization services should be improved, especially in western regions. Integration of current services to prevent MTCT of HBV with other relevant health services can increase the acceptability, efficiency, and coverage of these services, particularly in remote areas and ethnic minority areas. By doing so, progress toward key milestones and targets to eliminate hepatitis B as the main public health threat by 2030 can be achieved.
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