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The World Health Organization has a mandate to compile and disseminate statistics on mortality, and we have been tracking the progression of the COVID-19 pandemic since the beginning of 2020 1 . Reported statistics on COVID-19 mortality are problematic for many countries owing to variations in testing access, differential diagnostic capacity and inconsistent certification of COVID-19 as cause of death. Beyond what is directly attributable to it, the pandemic has caused extensive collateral damage that has led to losses of lives and livelihoods. Here we report a comprehensive and consistent measurement of the impact of the COVID-19 pandemic by estimating excess deaths, by month, for 2020 and 2021. We predict the pandemic period all-cause deaths in locations lacking complete reported data using an overdispersed Poisson count framework that applies Bayesian inference techniques to quantify uncertainty. We estimate 14.83 million excess deaths globally, 2.74 times more deaths than the 5.42 million reported as due to COVID-19 for the period. There are wide variations in the excess death estimates across the six World Health Organization regions. We describe the data and methods used to generate these estimates and highlight the need for better reporting where gaps persist. We discuss various summary measures, and the hazards of ranking countries’ epidemic responses. Msemburi et al. describe how the World Health Organization has estimated the excess mortality associated with the COVID-19 pandemic, by month and for 2020 and 2021, and analyse their estimates across the WHO member states, with 14.83 million global excess deaths estimated.

Gastric cancer remains a major cause of cancer-related mortality worldwide. The temporal trends for this malignancy, however, are dynamic, and reports from the past decade indicate important declines in some regions and demographic groups, as well as a few notable exceptions in which gastric cancer rates are either stable or increasing. Two main anatomical subtypes of gastric cancer exist, non-cardia and cardia, with different temporal trends and risk factors (such as obesity and reflux for cardia gastric cancer and Helicobacter pylori infection for non-cardia gastric cancer). Shifts in the distribution of anatomical locations have been detected in several high-incidence regions. H. pylori is an important aetiological factor for gastric cancer; importantly, the anticipated long-term findings from studies examining the effect of H. pylori eradication on the risk of (re)developing gastric cancer have emerged in the past few years. In this Review, we highlight the latest trends in incidence and mortality using an evidence-based approach. We make the best possible inferences, including clinical and public health inference, on the basis of the quality of the evidence available, and highlight burning questions as well as gaps in knowledge and public health practice that need to be addressed to reduce gastric cancer burden worldwide.Globally, gastric cancer is a common and highly fatal cancer with two anatomical subtypes, non-cardia and cardia gastric cancer. Helicobacter pylori causes almost 90% of distal gastric cancers worldwide. The authors of this Review summarize the current epidemiology of gastric cancer and the evidence and implications of primary and secondary prevention efforts.

Rheumatoid arthritis (RA) is a systemic autoimmune disease that predominantly affects the joints. The prevalence of RA varies globally, with generally a higher prevalence in industrialized countries, which may be explained by exposures to environmental risk factors, but also by genetic factors, differing demographics and under-reporting in other parts of the world. Over the past three decades, strong trends of the declining severity of RA probably reflect changes in treatment paradigms and overall better management of the disease. Other trends include increasing RA prevalence. Common risk factors for RA include both modifiable lifestyle-associated variables and non-modifiable features, such as genetics and sex. A better understanding of the natural history of RA, and of the factors that contribute to the development of RA in specific populations, might lead to the introduction of specific prevention strategies for this debilitating disease.In this Review, the authors summarize and discuss regional differences in the prevalence and incidence of rheumatoid arthritis (RA), and describe temporal trends associated with the disease as well as evidence related to risk factors.

Globally, ovarian cancer is the eighth most common cancer in women, accounting for an estimated 3.7% of cases and 4.7% of cancer deaths in 2020. Until the early 2000s, age-standardized incidence was highest in northern Europe and North America, but this trend has changed; incidence is now declining in these regions and increasing in parts of eastern Europe and Asia. Ovarian cancer is a very heterogeneous disease and, even among the most common type, namely epithelial ovarian cancer, five major clinically and genetically distinct histotypes exist. Most high-grade serous ovarian carcinomas are now recognized to originate in the fimbrial ends of the fallopian tube. This knowledge has led to more cancers being coded as fallopian tube in origin, which probably explains some of the apparent declines in ovarian cancer incidence, particularly in high-income countries; however, it also suggests that opportunistic salpingectomy offers an important opportunity for prevention. The five histotypes share several reproductive and hormonal risk factors, although differences also exist. In this Review, we summarize the epidemiology of this complex disease, comparing the different histotypes, and consider the potential for prevention. We also discuss how changes in the prevalence of risk and protective factors might have contributed to the observed changes in incidence and what this might mean for incidence in the future.Ovarian cancer, accounting for 4.7% of cancer deaths in women in 2020, remains highly prevalent globally. Nonetheless, owing to changes in environmental exposures, the approach to preventive measures and disease classification, both incidence and mortality have been declining in economically developed countries since the early 2000s. Conversely, parts of Asia and eastern Europe have seen increases in the incidence of ovarian cancer over this period of time. In this Review, the authors summarize the epidemiology of ovarian cancer, including the roles of the various risk factors and the potential for prevention.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused substantial global morbidity and deaths, leading governments to turn to non-pharmaceutical interventions to slow down the spread of infection and lessen the burden on health care systems. These policies have evolved over the course of the COVID-19 pandemic, including after the availability of COVID-19 vaccines, with regional and country-level differences in their ongoing use. The COVID-19 pandemic has been associated with changes in respiratory virus infections worldwide, which have differed between virus types. Reductions in respiratory virus infections, including by influenza virus and respiratory syncytial virus, were most notable at the onset of the COVID-19 pandemic and continued in varying degrees through subsequent waves of SARS-CoV-2 infections. The decreases in community infection burden have resulted in reduced hospitalizations and deaths associated with non-SARS-CoV-2 respiratory infections. Respiratory virus evolution relies on the maintaining of a diverse genetic pool, but evidence of genetic bottlenecking brought on by case reduction during the COVID-19 pandemic has resulted in reduced genetic diversity of some respiratory viruses, including influenza virus. By describing the differences in these changes between viral species across different geographies over the course of the COVID-19 pandemic, we may better understand the complex factors involved in community co-circulation of respiratory viruses.The COVID-19 pandemic has had a considerable impact on respiratory virus infections worldwide. In this Review, Chu and colleagues discuss the changes in community spread and consequent infections by respiratory viruses other than severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) throughout the course of the pandemic, and describe the impact on the evolution and genetic diversity of these viruses.

Three lineages (BA.1, BA.2 and BA.3) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant of concern predominantly drove South Africa’s fourth Coronavirus Disease 2019 (COVID-19) wave. We have now identified two new lineages, BA.4 and BA.5, responsible for a fifth wave of infections. The spike proteins of BA.4 and BA.5 are identical, and similar to BA.2 except for the addition of 69–70 deletion (present in the Alpha variant and the BA.1 lineage), L452R (present in the Delta variant), F486V and the wild-type amino acid at Q493. The two lineages differ only outside of the spike region. The 69–70 deletion in spike allows these lineages to be identified by the proxy marker of S-gene target failure, on the background of variants not possessing this feature. BA.4 and BA.5 have rapidly replaced BA.2, reaching more than 50% of sequenced cases in South Africa by the first week of April 2022. Using a multinomial logistic regression model, we estimated growth advantages for BA.4 and BA.5 of 0.08 (95% confidence interval (CI): 0.08–0.09) and 0.10 (95% CI: 0.09–0.11) per day, respectively, over BA.2 in South Africa. The continued discovery of genetically diverse Omicron lineages points to the hypothesis that a discrete reservoir, such as human chronic infections and/or animal hosts, is potentially contributing to further evolution and dispersal of the virus. Genomic characterization of the SARS-CoV-2 Omicron lineages BA.4 and BA.5, responsible for the fifth COVID-19 pandemic wave in South Africa, shows continued viral diversification and provides insights into the potential mechanisms underlying the ability of the new lineages to outcompete their predecessors.

Anecdotal evidence suggests that Coronavirus disease 2019 (COVID-19), caused by the coronavirus SARS-CoV-2, exhibits differences in morbidity and mortality between sexes. Here, we present a meta-analysis of 3,111,714 reported global cases to demonstrate that, whilst there is no difference in the proportion of males and females with confirmed COVID-19, male patients have almost three times the odds of requiring intensive treatment unit (ITU) admission (OR = 2.84; 95% CI = 2.06, 3.92) and higher odds of death (OR = 1.39; 95% CI = 1.31, 1.47) compared to females. With few exceptions, the sex bias observed in COVID-19 is a worldwide phenomenon. An appreciation of how sex is influencing COVID-19 outcomes will have important implications for clinical management and mitigation strategies for this disease. Anecdotal reports suggest potential severity and outcome differences between sexes following infection by SARS-CoV-2. Here, the authors perform meta-analyses of more than 3 million cases collected from global public data to demonstrate that male patients with COVID-19 are 3 times more likely to require intensive care, and have ~40% higher death rate.

Cirrhosis is an important cause of morbidity and mortality in people with chronic liver disease worldwide. In 2019, cirrhosis was associated with 2.4% of global deaths. Owing to the rising prevalence of obesity and increased alcohol consumption on the one hand, and improvements in the management of hepatitis B virus and hepatitis C virus infections on the other, the epidemiology and burden of cirrhosis are changing. In this Review, we highlight global trends in the epidemiology of cirrhosis, discuss the contributions of various aetiologies of liver disease, examine projections for the burden of cirrhosis, and suggest future directions to tackle this condition. Although viral hepatitis remains the leading cause of cirrhosis worldwide, the prevalence of non-alcoholic fatty liver disease (NAFLD) and alcohol-associated cirrhosis are rising in several regions of the world. The global number of deaths from cirrhosis increased between 2012 and 2017, but age-standardized death rates (ASDRs) declined. However, the ASDR for NAFLD-associated cirrhosis increased over this period, whereas ASDRs for other aetiologies of cirrhosis declined. The number of deaths from cirrhosis is projected to increase in the next decade. For these reasons, greater efforts are required to facilitate primary prevention, early detection and treatment of liver disease, and to improve access to care.In this Review, Huang et al. highlight global trends in the epidemiology of cirrhosis, including contributions of various aetiologies of liver disease, and consider what needs to be done to address projected increases in the burden of cirrhosis.

The SARS-CoV-2 epidemic in southern Africa has been characterized by three distinct waves. The first was associated with a mix of SARS-CoV-2 lineages, while the second and third waves were driven by the Beta (B.1.351) and Delta (B.1.617.2) variants, respectively 1 – 3 . In November 2021, genomic surveillance teams in South Africa and Botswana detected a new SARS-CoV-2 variant associated with a rapid resurgence of infections in Gauteng province, South Africa. Within three days of the first genome being uploaded, it was designated a variant of concern (Omicron, B.1.1.529) by the World Health Organization and, within three weeks, had been identified in 87 countries. The Omicron variant is exceptional for carrying over 30 mutations in the spike glycoprotein, which are predicted to influence antibody neutralization and spike function 4 . Here we describe the genomic profile and early transmission dynamics of Omicron, highlighting the rapid spread in regions with high levels of population immunity. The genomic profile and early transmission dynamics of the Omicron strain of SARS-CoV-2.

Haemodialysis (HD) is the commonest form of kidney replacement therapy in the world, accounting for approximately 69% of all kidney replacement therapy and 89% of all dialysis. Over the last six decades since the inception of HD, dialysis technology and patient access to the therapy have advanced considerably, particularly in high-income countries. However, HD availability, accessibility, cost and outcomes vary widely across the world and, overall, the rates of impaired quality of life, morbidity and mortality are high. Cardiovascular disease affects more than two-thirds of people receiving HD, is the major cause of morbidity and accounts for almost 50% of mortality. In addition, patients on HD have high symptom loads and are often under considerable financial strain. Despite the many advances in HD technology and delivery systems that have been achieved since the treatment was first developed, poor outcomes among patients receiving HD remain a major public health concern. Understanding the epidemiology of HD outcomes, why they might vary across different populations and how they might be improved is therefore crucial, although this goal is hampered by the considerable heterogeneity in the monitoring and reporting of these outcomes across settings.This Review examines the epidemiology of haemodialysis outcomes — clinical, patient-reported and surrogate outcomes — across world regions and populations, including vulnerable individuals. The authors also discuss the current status of monitoring and reporting of haemodialysis outcomes and potential strategies for improvement.