Obesity, race, and risk for death or functional decline among medicare beneficiaries: A cohort study

Background: The adverse effect of obesity on health outcomes may be lower in older and African American adults than in the general U.S. population. Objective: To examine and compare the relationship between obesity and all-cause mortality and functional decline among older U.S. adults. Design: Longitudinal cohort study. Setting: Secondary analysis of data from the 1994 to 2000 Medicare Current Beneficiary Surveys, linked to Medicare enrollment files through 22 April 2008. Participants: 20 975 community-dwelling participants in the 1994 to 2000 Medicare Current Beneficiary Surveys who were aged 65 years or older. Measurements: All-cause mortality through 22 April 2008; new or worsening disability in performing activities of daily living (ADLs) and instrumental activities of daily living (IADLs) in 2 years. Results: 37% of the study sample were overweight (body mass index [BMI] of 25 to <30 kg/m2), 18% were obese (BMI ≥30 kg/m2), 48% died during the 14-year follow-up, and 27% had ADL and 43% had IADL disability at baseline. Among those without severe disability at baseline, 17% developed new or worsening ADL disability and 26% developed new or worsening IADL disability within 2 years. After adjustment, adults with a BMI of 35 kg/m2 or greater were the only group above the normal BMI range who had a higher risk for mortality (hazard ratio, 1.49 [95% CI, 1.20 to 1.85] in men and 1.21 [CI, 1.06 to 1.39] in women, compared with the reference group [BMI of 22.0 to 24.9 kg/m2]; P for BMI–sex interaction = 0.003). In contrast, both overweight and obesity were associated with new or progressive ADL and IADL disability in a dose-dependent manner, particularly for white men and women. Significant interactions were detected between BMI and sex but not between BMI and race for any outcome, although risk estimates for ADL disability seemed attenuated in African American relative to white respondents. Limitation: This was an observational study, baseline data were self-reported, and the study had limited power to detect differences between white and African American respondents. Conclusion: Among older U.S. adults, obesity was not associated with mortality, except for those with at least moderately severe obesity. However, lower levels of obesity were associated with new or worsening disability within 2 years. Efforts to prevent disability in older adults should target those who are overweight or obese

Risk of COVID-19 after natural infection or vaccinationResearch in context

Summary: Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health

Risk of COVID-19 after natural infection or vaccinationResearch in context

Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health