Objectives: It is unclear whether agricultural workers working during epidemics frequently introduce respiratory infections into their homes and trigger secondary transmission. We evaluate secondary attack rates (SAR) and transmission risk in households of agricultural workers in Guatemala during the COVID-19 pandemic. Methods: Households of participants in a workplace surveillance cohort were enrolled from September 2021 to August 2023. All participants reported symptoms twice weekly and provided saliva weekly for SARS-CoV-2 reverse-transcriptase-polymerase chain reaction testing. Upon SARS-CoV-2 detection, participants submitted saliva three times per week for 4 weeks. We calculated SARs, and we estimated the risk of transmission to household contacts adjusting for demographic factors, COVID-19 vaccination status, seropositivity, and significant covariates (p ≤ 0.05) in univariable analyses. Results: Among 83 households with 376 individuals, 48 (58%) had at least one SARS-CoV-2 infection (120 SARS-CoV-2 infections, 0.6 per 100 person-weeks), resulting in 64 secondary (SAR = 0.35, 95% confidence interval [CI] 0.28-0.43) and eight tertiary infections (tertiary attack rate = 0.07, 95% CI 0.03-0.13). The risk of secondary transmission increased by 112% among household contacts whose index cases were positive for ≥11 days (risk ratio: 2.12, 95% CI 1.29-3.49) but did not increase for those whose index case was positive for 6-10 days (risk ratio: 1.40, 95% CI 0.77-2.57) compared to those with index cases positive for ≤5 days. Conclusions: More than half of agricultural households became infected with SARS-CoV-2 and approximately two-thirds of these had secondary chains of transmission, especially when index cases shed SARS-CoV-2 longer. © 2025 The Authors

BACKGROUND: Estimating the burden of disease averted by vaccination can assist policymakers to implement, adjust, and communicate the value of vaccination programs. Demonstrating the use of a newly available modeling tool, we estimated the burden of influenza illnesses averted by seasonal influenza vaccination in El Salvador, Panama, and Peru during 2011-2017 among two influenza vaccine target populations: children aged 6-23 months and pregnant women. METHODS: We derived model inputs, including incidence, vaccine coverage, vaccine effectiveness, and multipliers from publicly available country-level influenza surveillance data and cohort studies. We also estimated changes in illnesses averted when countries' vaccine coverage was achieved using four different vaccine deployment strategies. RESULTS: Among children aged 6-23 months, influenza vaccination averted an estimated cumulative 2,161 hospitalizations, 81,907 medically-attended illnesses, and 126,987 overall illnesses during the study period, with a prevented fraction ranging from 0.3 % to 12.5 %. Among pregnant women, influenza vaccination averted an estimated cumulative 173 hospitalizations, 6,122 medically attended illnesses, and 16,412 overall illnesses, with a prevented fraction ranging from 0.2 % to 10.9 %. Compared to an influenza vaccine campaign with equal vaccine distribution during March-June, scenarios in which total cumulative coverage was achieved in March and April consistently resulted in the greatest increase in averted illness (23 %-3,129 % increase among young children and 22 %-3,260 % increase among pregnant women). DISCUSSION: Influenza vaccination campaigns in El Salvador, Panama, and Peru conducted between 2011 and 2018 prevented hundreds to thousands of influenza-associated hospitalizations and illnesses in young children and pregnant women. Existing vaccination programs could prevent additional illnesses, using the same number of vaccines, by achieving the highest possible coverage within the first two months of an influenza vaccine campaign.