Integrated SARS-CoV-2 serological and virological screening across an acute fever surveillance platform to monitor temporal changes in anti-spike antibody levels and risk of infection during sequential waves of variant transmission - Dominican Republic, March 2021 to August 2022 (preprint)

We monitored SARS-CoV-2 antibody changes following implementation of a national COVID-19 vaccination campaign and assessed implications for immunological protection against variants of concern. Between March 2021 and August 2022, we prospectively enrolled 2,300 patients seeking care for undifferentiated febrile illnesses across two study sites in the Dominican Republic. Sera was tested for total anti-spike antibodies (anti-S) and simultaneously collected nasopharyngeal samples by RT-PCR for acute SARS-CoV-2 infection. Geometric mean anti-S titers increased from 6.6 BAU/ml (95% CI 5.1-8.7) to 1,332 BAU/ml (CI 1055-1,682) during the study period. Multivariable binomial odds ratios for acute SARS-CoV-2 infection were 0.55 (0.40-0.74), 0.38 (0.27-0.55), and 0.27 (0.18-0.40) for the second, third, and fourth versus the first anti-S quartile, with similar findings by viral strain. Integrated serological and virological screening present an opportunity to rethink existing surveillance platforms by simultaneously monitoring population-level immunological markers and implications for emerging variant transmission.

Clinical and Economic Impact of COVID-19 on Plantation Workers: Preliminary Results from the Guatemala Agricultural Workers and Respiratory Illness Impact (AGRI) Study (preprint)

We evaluated the clinical and socioeconomic burdens of respiratory disease in a cohort of Guatemalan banana plantation workers. All eligible workers were offered enrollment from June 15 to December 30, 2020, and annually, then followed for influenza-like illnesses (ILI) through: 1) self-reporting to study nurses, 2) sentinel surveillance at health posts, and 3) absenteeism. Workers with ILI submitted nasopharyngeal swabs for influenza, RSV, and SARS-CoV-2 testing, then completed surveys at days 0, 7, and 28. Through October 10, 2021, 1,833 workers developed 169 ILIs (12.0/100 person-years) and 43 (25.4%) of these ILIs were laboratory-confirmed SARS-CoV-2 (3.1/100 person-years). Workers with SARS-CoV-2-positive ILI reported more anosmia (p<0.01), dysgeusia (p<0.01), difficulty concentrating (p=0.01), and irritability (p=0.01), and greater clinical and well-being severity scores (Flu-iiQ) than test-negative ILIs; they also had greater absenteeism (p<0.01) and lost income (median US$127.1, p<0.01). These results support the prioritization of Guatemalan farm workers for COVID-19 vaccination.