Spurious early ecological association suggesting BCG vaccination effectiveness for COVID-19.

BACKGROUND: Several ecologic studies have suggested that the bacillus Calmette-Guérin (BCG) vaccine may be protective against SARS-CoV-2 infection including a highly-cited published pre-print by Miller et al., finding that middle/high- and high-income countries that never had a universal BCG policy experienced higher COVID-19 burden compared to countries that currently have universal BCG vaccination policies. We provide a case study of the limitations of ecologic analyses by evaluating whether these early ecologic findings persisted as the pandemic progressed. METHODS: Similar to Miller et al., we employed Wilcoxon Rank Sum Tests to compare population medians in COVID-19 mortality, incidence, and mortality-to-incidence ratio between countries with universal BCG policies compared to those that never had such policies. We then computed Pearson's r correlations to evaluate the association between year of BCG vaccination policy implementation and COVID-19 outcomes. We repeated these analyses for every month in 2020 subsequent to Miller et al.'s March 2020 analysis. RESULTS: We found that the differences in COVID-19 burden associated with BCG vaccination policies in March 2020 generally diminished in magnitude and usually lost statistical significance as the pandemic progressed. While six of nine analyses were statistically significant in March, only two were significant by the end of 2020. DISCUSSION: These results underscore the need for caution in interpreting ecologic studies, given their inherent methodological limitations, which can be magnified in the context of a rapidly evolving pandemic in which there is measurement error of both exposure and outcome status.

COVID-19 vaccine misinformation in English-language news media: retrospective cohort study.

OBJECTIVES: To describe COVID-19 vaccine misinformation and track trends over time in traditional news media. DESIGN: Retrospective cohort study of a large database of online articles, July 2020-June 2021. SETTING: English-language articles from 100 news outlets with the greatest reach. MAIN OUTCOME MEASURES: Numbers and percentages of articles containing COVID-19 vaccine misinformation over the study period. Further analysis by misinformation themes and whether articles included primary misinformation, fact-checking or simply referred to misinformation. RESULTS: 41 718 (3.2% of all COVID-19 vaccine articles) contained at least one of the vaccine misinformation themes based on the Boolean string developed for this study. The volume of such articles increased beginning in November 2020, but their percentage of all articles remained essentially stable after October 2020. 56.2% contained at least one mention of a safety theme, followed by development, production, and distribution (26.6%), and conspiracies (15.1%). Of 500 articles through January 2021 randomly selected from those identified by the Boolean string, 223 were not relevant, and 277 included either fact-checking (175 articles), refers to misinformation (87 articles) or primary misinformation (15 articles). In eight study weeks, the reach of these 277 articles (defined as visitors to the sites containing the articles) exceeded 250 million people. Fact-checking accounted for 69.6% of all reach for these articles and the number of such articles increased after November 2020. Overall, approximately 0.1% (95% CI 0.05% to 0.16%) of all articles on COVID-19 vaccines in our sample contained primary misinformation. CONCLUSIONS: COVID-19 vaccine misinformation in traditional news media is uncommon but has the capacity to reach large numbers of readers and affect the vaccine conversation. Recent increases in fact-checking may counteract some of the misinformation currently circulating.

Agreement of treatment effects from observational studies and randomized controlled trials evaluating hydroxychloroquine, lopinavir-ritonavir, or dexamethasone for covid-19: meta-epidemiological study.

OBJECTIVE: To systematically identify, match, and compare treatment effects and study demographics from individual or meta-analysed observational studies and randomized controlled trials (RCTs) evaluating the same covid-19 treatments, comparators, and outcomes. DESIGN: Meta-epidemiological study. DATA SOURCES: National Institutes of Health Covid-19 Treatment Guidelines, a living review and network meta-analysis published in The BMJ, a living systematic review with meta-analysis and trial sequential analysis in PLOS Medicine (The LIVING Project), and the Epistemonikos "Living OVerview of Evidence" (L·OVE) evidence database. ELIGIBILITY CRITERIA FOR SELECTION OF STUDIES: RCTs in The BMJ's living review that directly compared any of the three most frequently studied therapeutic interventions for covid-19 across all data sources (that is, hydroxychloroquine, lopinavir-ritonavir, or dexamethasone) for any safety and efficacy outcomes. Observational studies that evaluated the same interventions, comparisons, and outcomes that were reported in The BMJ's living review. DATA EXTRACTION AND SYNTHESIS: Safety and efficacy outcomes from observational studies were identified and treatment effects for dichotomous (odds ratios) or continuous (mean differences or ratios of means) outcomes were calculated and, when possible, meta-analyzed to match the treatment effects from individual RCTs or meta-analyses of RCTs reported in The BMJ's living review with the same interventions, comparisons, and outcomes (that is, matched pairs). The analysis compared the distribution of study demographics and the agreement between treatment effects from matched pairs. Matched pairs were in agreement if both observational and RCT treatment effects were significantly increasing or decreasing (P<0.05) or if both treatment effects were not significant (P≥0.05). RESULTS: 17 new, independent meta-analyses of observational studies were conducted that compared hydroxychloroquine, lopinavir-ritonavir, or dexamethasone with an active or placebo comparator for any safety or efficacy outcomes in covid-19 treatment. These studies were matched and compared with 17 meta-analyses of RCTs reported in The BMJ's living review. 10 additional matched pairs with only one observational study and/or one RCT were identified. Across all 27 matched pairs, 22 had adequate reporting of demographical and clinical data for all individual studies. All 22 matched pairs had studies with overlapping distributions of sex, age, and disease severity. Overall, 21 (78%) of the 27 matched pairs had treatment effects that were in agreement. Among the 17 matched pairs consisting of meta-analyses of observational studies and meta-analyses of RCTs, 14 (82%) were in agreement; seven (70%) of the 10 matched pairs consisting of at least one observational study or one RCT were in agreement. The 18 matched pairs with treatment effects for dichotomous outcomes had a higher proportion of agreement (n=16, 89%) than did the nine matched pairs with treatment effects for continuous outcomes (n=5, 56%). CONCLUSIONS: Meta-analyses of observational studies and RCTs evaluating treatments for covid-19 have summary treatment effects that are generally in agreement. Although our evaluation is limited to three covid-19 treatments, these findings suggest that meta-analyzed evidence from observational studies might complement, but should not replace, evidence collected from RCTs.

Trials for second generation Covid-19 vaccines: Revisiting the debate over placebo use in developing country clinical trials.

This article compares the current debate over the use of placebos in developing country clinical trials of second generation Covid-19 vaccines with the debates over previous paradigmatic cases raising similar issues. Compared to the earlier zidovudine and Surfaxin trials, Covid-19 vaccine trials are likely to confer lower risk to placebo groups and to offer a greater number and variety of alternative study designs. However, turning to the developing world to conduct studies that would be unacceptable in developed countries, simply on the ground that Covid-19 vaccines are generally unavailable in developing countries, is not ethically justifiable. This is so whether the justification is rooted in total absence of vaccine in a given country or in developing country vaccine prioritisation practices, because at root both derive from economic, not scientific conditions. However, the advent of variants that may create genuine uncertainty as to comparator vaccine effectiveness could justify a placebo control, depending on vaccine characteristics, variant prevalence, the degree of variant resistance, and the acceptability of immune-bridging studies. These factors must be considered together in the necessary case-by-case assessment of the ethical justification for any proposed trial.