Association Between mRNA Vaccination and Infection From SARS-CoV-2 During the Delta and Omicron BA.1 Waves: A Population-Level Analysis.

Introduction: COVID-19 mRNA vaccine protection against the Omicron variant of SARS-CoV-2 has been shown to be attenuated. Previous research in Shelby County, Tennessee found that vaccine effectiveness might differ by age in the Omicron surge, a finding not reported for other variants. To assess whether patterns in vaccine effectiveness by age group differed on the basis of the predominant strain of SARS-CoV2, we evaluated vaccine effectiveness in Shelby County, Tennessee by age group in the Delta wave and Omicron BA.1 (Omicron) wave. Methods: Case and vaccination statuses of residents were assessed using COVID-19 surveillance data. Age was stratified as 18-34, 35-64, and ≥65 years. Vaccination groups included unvaccinated, fully vaccinated, and fully vaccinated + booster. Person time was counted in each wave by vaccination status until the time of a positive reported COVID-19 test or until the end of the study period. Results: Incidence of COVID-19 was much higher during the Omicron wave than during the Delta wave across all vaccination groups. During the Delta wave, among adults, 79.2% fewer cases were identified in those fully vaccinated and 94.8% fewer in those fully vaccinated + booster, compared with 40.2% and 66.7%, respectively, in the Omicron wave, compared with those who were unvaccinated. Conclusions: This study found evidence that vaccine effectiveness differed by age group during the Omicron wave, where the same pattern was not prominent in the Delta wave. Further analysis investigating the influence of behavior patterns and other potential confounders on vaccine effectiveness would be useful in further understanding the relationship between age and vaccine effectiveness.

Associations Between Breastfeeding and Post-perinatal Infant Deaths in the U.S.

INTRODUCTION: Initiation of breastfeeding has been associated with reduced post-perinatal infant mortality. Although most states have initiatives to protect, promote, and support breastfeeding, no analysis of the association between breastfeeding and infant mortality has been conducted at the state and regional levels. To understand the associations between breastfeeding and post-perinatal infant mortality, the initiation of breastfeeding with post-perinatal infant mortality was analyzed by geographic region and individual states within each region. METHODS: This study was a prospective cohort analysis linking U.S. national birth and post-perinatal infant death data for nearly 10 million infants born in 2016-2018, who were then followed for one year after birth and analyzed in 2021-2022. RESULTS: A total of 9,711,567 live births and 20,632 post-perinatal infant deaths from 48 states and the District of Columbia were included in the analysis. The overall AOR and 95% CIs for breastfeeding initiation with post-perinatal infant mortality was 0.67 (0.65, 0.69, p<0.0001) for days 7-364. All seven U.S. geographic regions had significant reductions in postperinatal infant deaths associated with breastfeeding initiation; Mid-Atlantic and Northeast regions had the largest reductions with AOR of 0.56 (95% CI=0.51, 0.61, p<0.001 and 0.50, 0.63, p<0.001, respectively), whereas the Southeast had the smallest reduction with AOR of 0.79 (95% CI=0.75, 0.84, p<0.001). Statistically significant results were noted for 35 individual states for reduction in total post-perinatal infant deaths. CONCLUSIONS: Although regional and state variation in the magnitude of the association between breastfeeding and infant mortality exists, the consistency of reduced risk, together with existing literature, suggests that breastfeeding promotion and support may be a strategy to reduce infant mortality in the U.S.

Real-World Association Between mRNA Vaccination and Infection From the Omicron Strain of SARS-CoV-2: A Population-Level Analysis.

Introduction: Two mRNA vaccines approved in the U.S. have high efficacy against COVID-19 disease from the original strain of SARS-CoV-2. We evaluated the population-level association between vaccination status and COVID-19 infection by age group during the initial wave of the Omicron variant in a diverse population in the Mid-South U.S. Methods: In this observational population-based cohort study, vaccination information and positive COVID-19 cases in Shelby County, Tennessee, from December 12, 2021 through January 22, 2022 were collected from surveillance data at the Shelby County Health Department (Memphis, Tennessee). Exposure groups included individuals who were unvaccinated, were fully vaccinated, and were fully vaccinated + booster. We calculated incidence rates of COVID-19 diagnosis per person-year among county adult (aged 18+ years) residents in crude form and stratified by age group. Results: In this population-based study, we identified 64.56% fewer COVID-19 infections in the fully vaccinated + booster group and 41.08% fewer in the fully vaccinated group than in the unvaccinated group. Conclusions: These results confirm and extend the findings of recent immunologic and epidemiologic studies in a racially diverse region of the Mid-South U.S. In stratified analysis, we also found evidence suggesting that vaccine protection against Omicron may increase with age.

Breastfeeding and post-perinatal infant deaths in the United States, A national prospective cohort analysis.

Background: Reducing infant mortality is a major public health goal. The potential impact of breastfeeding on infant deaths is not well studied in the United States (US). Methods: We analyzed linked birth-death certificates for 3,230,500 US births that occurred in 2017, including 6,969 post-perinatal deaths from 7-364 days of age as the primary outcome, further specified as late-neonatal (7-27 days) or post-neonatal (28-364 days) deaths. The primary exposure was 'ever breastfed' obtained from birth certificates. Multiple logistic regression examined associations of ever breastfeeding with post-perinatal deaths and specific causes of deaths, controlling for maternal and infant factors. Findings: We observed an adjusted reduced odds ratio (AOR)= 0·74 with 95% confidence intervals (CI)=0·70-0·79 for the association of breastfeeding initiation with overall infant deaths (7-364 days), AOR=0·60 (0·54-0·67) for late-neonatal deaths, and AOR=0·81 (0·76-0·87) for post-neonatal deaths. In race/ethnicity-stratified analysis, significant associations of breastfeeding initiation with reduced odds of overall infant deaths were observed for Hispanics [AOR=0·64 (0·55-0·74)], non-Hispanic Whites [AOR=0·75 (0·69-0·81)], non-Hispanic Blacks [AOR=0·83 (0·75-0·91)], and non-Hispanic Asians [AOR=0·51 (0·36-0·72)]. Across racial/ethnic groups, effect sizes for late-neonatal deaths were consistently larger than those for post-neonatal deaths. Significant effects of breastfeeding initiation were observed for deaths due to infection [AOR=0·81(0·69-0·94)], Sudden Unexpected Infant Death [AOR=0·85 (0·78-0·92)], and necrotizing enterocolitis [AOR=0·67 (0·49-0·90)]. Interpretation: Breastfeeding initiation is significantly associated with reduced odds of post-perinatal infant deaths in multiple racial and ethnic groups within the US population. These findings support efforts to improve breastfeeding in infant mortality reduction initiatives.

Using protection motivation theory and formative research to guide an injury prevention intervention: increasing adherence to the North American Guidelines for Children's Agricultural Tasks.

The North American Guidelines for Children's Agricultural Tasks (NAGCAT) were developed to reduce childhood agricultural injuries by assisting adults in assigning appropriate chores and providing needed supervision and training. To develop an effective intervention to increase adherence to NAGCAT among farm parents, formative research (focus groups and pilot-testing) was conducted. Protection motivation theory (PMT) was used to guide this research and inform intervention development. Focus group results suggested how PMT constructs might be addressed to increase adherence. A home visit intervention, using a standardized presentation in POWERPoint™, was developed to (a) introduce NAGCAT, (b) increase motivation to use NAGCAT and enhance safe work behaviors, and (c) ultimately reduce agricultural work-related injuries among youth. Process evaluation data suggests that the intervention was well received by farm parents. Conducting theory-guided formative research identified motivational barriers and strategies for overcoming these barriers that might not have been otherwise apparent.