COVID-19 Mask Usage and Social Distancing in Social Media Images: Large-scale Deep Learning Analysis.

BACKGROUND: The adoption of nonpharmaceutical interventions and their surveillance are critical for detecting and stopping possible transmission routes of COVID-19. A study of the effects of these interventions can help shape public health decisions. The efficacy of nonpharmaceutical interventions can be affected by public behaviors in events, such as protests. We examined mask use and mask fit in the United States, from social media images, especially during the Black Lives Matter (BLM) protests, representing the first large-scale public gatherings in the pandemic. OBJECTIVE: This study assessed the use and fit of face masks and social distancing in the United States and events of large physical gatherings through public social media images from 6 cities and BLM protests. METHODS: We collected and analyzed 2.04 million public social media images from New York City, Dallas, Seattle, New Orleans, Boston, and Minneapolis between February 1, 2020, and May 31, 2020. We evaluated correlations between online mask usage trends and COVID-19 cases. We looked for significant changes in mask use patterns and group posting around important policy decisions. For BLM protests, we analyzed 195,452 posts from New York and Minneapolis from May 25, 2020, to July 15, 2020. We looked at differences in adopting the preventive measures in the BLM protests through the mask fit score. RESULTS: The average percentage of group pictures dropped from 8.05% to 4.65% after the lockdown week. New York City, Dallas, Seattle, New Orleans, Boston, and Minneapolis observed increases of 5.0%, 7.4%, 7.4%, 6.5%, 5.6%, and 7.1%, respectively, in mask use between February 2020 and May 2020. Boston and Minneapolis observed significant increases of 3.0% and 7.4%, respectively, in mask use after the mask mandates. Differences of 6.2% and 8.3% were found in group pictures between BLM posts and non-BLM posts for New York City and Minneapolis, respectively. In contrast, the differences in the percentage of masked faces in group pictures between BLM and non-BLM posts were 29.0% and 20.1% for New York City and Minneapolis, respectively. Across protests, 35% of individuals wore a mask with a fit score greater than 80%. CONCLUSIONS: The study found a significant drop in group posting when the stay-at-home laws were applied and a significant increase in mask use for 2 of 3 cities where masks were mandated. Although a positive trend toward mask use and social distancing was observed, a high percentage of posts showed disregard for the guidelines. BLM-related posts captured the lack of seriousness to safety measures, with a high percentage of group pictures and low mask fit scores. Thus, the methodology provides a directional indication of how government policies can be indirectly monitored through social media.

Effect of inclusion of hepatitis B vaccine in childhood immunization program in India: a retrospective cohort study.

OBJECTIVE: To assess the effectiveness of hepatitis B immunization program in a field setting in India. DESIGN: Serological survey of retrospective cohorts of children, vaccinated or not vaccinated with hepatitis B vaccine. SETTING: Rural field areas of five districts in Andhra Pradesh state, where childhood hepatitis B immunization began in 2003. PARTICIPANTS: Children aged 5-11 years who had received HB immunization (n=2674; 1357 boys) or not received such immunization (n=2350; 1236 boys). MAIN OUTCOME MEASURES: Serum HBsAg, anti-HBc and anti-HBs (quantitative) using automated enzyme-immunoassays in the year 2010. RESULTS: Anti-HBs positivity was higher among immunized than in unimmunized children (53% vs.18%; P<0.001), and anti-HBc positivity was lower (1.1% vs 10.8%: P<0.01). HBsAg positivity was low in both the groups (0.15% and 0.17%; P=0.855). Anti-HBs positivity rate declined with increasing age. CONCLUSIONS: Administration of hepatitis B vaccine as part of Universal immunization program led to anti-HBs in a large proportion of children and a reduction in anti-HBc positivity, a marker of hepatitis B virus infection. These data provide evidence supporting efficacy of hepatitis B immunization program in an Indian field setting, justifying the decision to include it in the universal immunization program.