The Journal of Medical Internet Research (JMIR) Public Health and Surveillance is "a multidisciplinary journal that focuses on public health and technology, public health informatics, mass media campaigns, surveillance, participatory epidemiology, and innovation in public health practice and research." This issue contains the following articles:  "One Year of Pandemic Learning Response: Benefits of Massive Online Delivery of the World Health Organization's Technical Guidance";  "Test, Trace, and Put on the Blockchain?: A Viewpoint Evaluating the Use of Decentralized Systems for Algorithmic Contact Tracing to Combat a Global Pandemic";  "Web-Based Apps for Responding to Acute Infectious Disease Outbreaks in the Community: Systematic Review";  "Convalescent Plasma for the Prevention and Treatment of COVID-19 [coronavirus disease 2019]: A Systematic Review and Quantitative Analysis";  "The Psychosocial Predictors and Day-Level Correlates of Substance Use Among Participants Recruited via an Online Crowdsourcing Platform in the United States: Daily Diary Study";  "Exploring the Association Between Physical Activity and Risk of Mental Health Disorders in Saudi Arabian Adults: Cross-sectional Study";  "Association of Opioid Use Disorder With 2016 Presidential Voting Patterns: Cross-sectional Study in New York State at Census Tract Level";  "Respondent Characteristics and Dietary Intake Data Collected Using Web-Based and Traditional Nutrition Surveillance Approaches: Comparison and Usability Study";  "The Impact of the COVID-19 Pandemic on the Uptake of Influenza Vaccine: UK-Wide Observational Study";  "Impact of Firearm Surveillance on Gun Control Policy: Regression Discontinuity Analysis";  "Public Discourse Against Masks in the COVID-19 Era: Infodemiology Study of Twitter Data";  "Reporting and Availability of COVID-19 Demographic Data by US Health Departments (April to October 2020): Observational Study";  "The Causality Inference of Public Interest in Restaurants and Bars on Daily COVID-19 Cases in the United States: Google Trends Analysis";  "Community and Campus COVID-19 Risk Uncertainty Under University Reopening Scenarios: Model-Based Analysis";  "Physical Activity, Nutritional Habits, and Sleeping Behavior in Students and Employees of a Swiss University During the COVID-19 Lockdown Period: Questionnaire Survey Study";  "'Thought I'd Share First' and Other Conspiracy Theory Tweets from the COVID-19 Infodemic: Exploratory Study";  "A Recursive Model of the Spread of COVID-19: Modelling Study";  "The Impact of COVID-19 Management Policies Tailored to Airborne SARS-CoV-2 [severe acute respiratory syndrome coronavirus 2] Transmission: Policy Analysis";  "Consumer-Based Activity Trackers as a Tool for Physical Activity Monitoring in Epidemiological Studies During the COVID-19 Pandemic: Development and Usability Study";  "Texas Public Agencies' Tweets and Public Engagement During the COVID-19 Pandemic: Natural Language Processing Approach";  "Latin America and the Caribbean SARS-CoV-2 Surveillance: Longitudinal Trend Analysis";  "Association Between Smoking and SARS-CoV-2 Infection: Cross-sectional Study of the EPICOVID19 Internet-Based Survey";  "Effects of Age, Gender, Health Status, and Political Party on COVID-19-Related Concerns and Prevention Behaviors: Results of a Large, Longitudinal Cross-sectional Survey";  "Surveillance of the Second Wave of COVID-19 in Europe: Longitudinal Trend Analyses";  "Correction: Assessment of the Effectiveness of Identity-Based Public Health Announcements in Increasing the Likelihood of Complying With COVID-19 Guidelines: Randomized Controlled Cross-sectional Web-Based Study";  "Correction: Early Detection of Dengue Fever Outbreaks Using a Surveillance App (Mozzify): Cross-sectional Mixed Methods Usability Study";  "Assessment of the Effectiveness of Identity-Based Public Health Announcements in Increasing the Likelihood of Complying With COVID-19 Guidelines: Randomized Controlled Cross-sectional Web-Based Study"; and  "Coinfection With SARS-CoV-2 and Influenza A(H1N1) in a Patient Seen at an Influenza-like Illness Surveillance Site in Egypt: Case Report."
JMIR Public Health and Surveillance: https://publichealth.jmir.org/
JMIR Public Health and Surveillance (2021), v.7 issue 4