The new Coronavirus SARS-CoV-2 has infected more than three million people worldwide so far. Brazil is currently the second leading country in number of critical cases and the third in number of new deaths caused by COVID-19, while São Paulo State accounts for more than 33% of total con rmed cases in Brazil. Therefore, understanding the mechanisms of SARS-CoV-2 spread in São Paulo State is an important task. The aim of this study was to assess environmental and social factors in uencing the spread of SARS-CoV-2 in the expanded metropolitan area of São Paulo, Brazil. Firstly, a spatial analysis was conducted to provide insights into the spread of COVID-19 within the expanded metropolitan area. Moreover, statistical analyses were performed to assess social indicators and environmental conditions which possibly in uence the incidence of COVID-19. Our results reveal that the spread of COVID-19 from the capital city São Paulo-its epicenter in Brazil-is directly associated with the availability of highways within the expanded metropolitan area of São Paulo. As for social aspects, cumulative COVID-19 con rmed cases were found to be both positively correlated with population density, and negatively correlated with social isolation rate, hence, indicating that social distancing has been effective in reducing the COVID-19 transmission. Finally, cumulative COVID-19 con rmed cases were found to be inversely correlated with both temperature and UV radiation. Together with recent literature our study suggests that the UV radiation provided by sunlight might reduce the infectivity of SARS-CoV-2.

Key Points Question What is the percentage of asymptomatic individuals with positive test results for SARS-CoV-2 among tested individuals and those with confirmed COVID-19 diagnosis? Findings In this systematic review and meta-analysis of 95 unique studies with 29 776 306 individuals undergoing testing, the pooled percentage of asymptomatic infections was 0.25% among the tested population and 40.50% among the population with confirmed COVID-19. Meaning The high percentage of asymptomatic infections from this study highlights the potential transmission risk of asymptomatic infections in communities.

Hepatitis B virus (HBV) infection is a major public health problem worldwide. China has the world’s largest burden of HBV infection and will be a major contributor towards the global elimination of hepatitis B disease by 2030. The country has made good progress in reducing incidence of HBV infection in the past three decades. The achievements are mainly due to high vaccination coverages among children and high coverage of timely birth-dose vaccine for prevention of mother-to-child transmission of HBV (both > 95%). However, China still faces challenges in achieving its target of 65% reduction in mortality from hepatitis B by 2030. Based on targets of the World Health Organization’s Global health sector strategy on viral hepatitis 2016–2021 , we highlight further priorities for action towards HBV elimination in China. To achieve the impact target of reduced mortality we suggest that the service coverage targets of diagnosis and treatment should be prioritized. First, improvements are needed in the diagnostic and treatment abilities of medical institutions and health workers. Second, the government needs to reduce the financial burden of health care on patients. Third, better coordination is needed across existing national programmes and resources to establish an integrated prevention and control system that covers prevention, screening, diagnosis and treatment of HBV infection across the life cycle. In this way, progress can be made towards achieving the target of eliminating hepatitis B in China by 2030.

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.

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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 12 m/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.

Background: China has the largest disease burden of hepatitis B virus (HBV) infection and is considered as a major contributor to the global elimination of hepatitis B by 2030. However, the national prevalence of HBV infection among Chinese pregnant women was not reported yet. We evaluated the national and regional prevalence of HBV infection among pregnant women in China between 2015-2020, aiming to provide the latest baseline data. Methods: We assessed the prevalence of HBV infection from data gathered through a nationwide crosssectional study of Chinese pregnant women. Data were obtained from the National Integrated Prevention of Mother-to-Child Transmission of HIV, Syphilis and Hepatitis B Programme (iPMTCT Programme) in China, which covered all the 2856 counties from 31 provinces from 2015 to 2020. HBV infection was defined as being tested seropositive for hepatitis B surface antigen (HBsAg). Findings: A total of 90.87 million pregnant women in mainland China were testing for HBV between 2015 and 2020, with 5.60 million (6.17%, 95%CI: 6.16-6.18%) tested positive for HBsAg. From 2015 to 2020, the prevalence of HBV infection among pregnant women declined by 25.44%, from 7.30% in 2015 to 5.44% in 2020 (p for trend < 0.001), with an estimated annual percentage change (EAPC) of -5.27% (95% CI: -3.19% to -7.32%). Compared with the prevalence in 2015, reginal disparities in eastern, central, and western China were narrowed. Declines were also observed at provincial level and county level. HBV prevalence declined in most provinces (90.3%, 28/31) and counties (76.96%, 2198/2856) from 2015 to 2020. However, disparities still exist. Interpretation: HBV prevalence in pregnant women in China was intermediate endemic and declined continuously from 2015 to 2020. The decline has been widespread across regions, but disparities remain. Regions with relatively higher disease burden on HBV infection should receive most attention in achieving the 2030 elimination goals.

Introduction Dengue, as a neglected tropical disease, brings a heavy socioeconomic burden. To provide tailored global prevention strategies, we analyzed the global trends and regional differences in incidence of dengue infection from 1990 to 2019. Methods We obtained data on annual dengue episodes and incidence rates, which reflected the epidemic status of dengue infection from the 2019 Global Burden of Disease (GBD) Study. The changes in dengue episodes and estimated annual percentage changes (EAPCs) of the age-standardized incidence rate (ASR) were calculated to quantify the temporal trends of dengue infection. Results Globally, dengue ASR increased by 1.70% (95% CI 1.62%–1.78%) per year from 1990 to 2011; subsequently, it decreased by 0.41% (95% CI 0.20%–0.62%) per year from 2011 to 2019. However, the global number of dengue episodes increased steadily by 85.47% from 30.67 million in 1990 to 56.88 million in 2019. Against the global trend of decreasing ASR from 2011 to 2019, an increasing trend was reported in Oceania (EAPC 11.01, 95% CI 8.79–13.27), East Asia (EAPC 4.84, 95% CI 2.70–7.03) and Southeast Asia (EAPC 0.38, 95% CI 0.13–0.62). For socio-demographic index (SDI) regions, ASR continued to have an increasing trend in the middle (EAPC 0.26, 95% CI 0.07–0.45) and high-middle (EAPC 1.70, 95% CI 0.98–2.42) SDI regions from 2011 to 2019. In contrast to the global peak age of dengue incidence rate (10 to 25 years), the dengue incidence rate of older people (> 65 years) was higher than in other age groups in low and low-middle SDI regions. Additionally, the proportions of dengue episodes in the > 70-year-old age group increased in 2019 (using the baseline in 1990 or 2011) in most GBD regions. Conclusions Global dengue episodes have increased tremendously in 3 decades. Although global dengue ASR decreased in the last decade, it is still increasing in hyperendemic regions including Oceania, East Asia and Southeast Asia, and also in the middle and high-middle SDI regions. More attention should be paid to the elderly because of the higher dengue incidence rate among them in low and low-middle SDI regions and the increased proportions of dengue episodes among the elderly in most GBD regions. Therefore, more efforts should be undertaken to develop targeted prevention strategies for crucial regions and older populations. Supplementary Information The online version contains supplementary material available at 10.1007/s40121-021-00470-2.