Influenza Burden Among Agricultural Households Highlights Need for Broader Vaccination Programs

Findings presented at IDWeek 2025, which took place from October 19 to October 22, 2025, in Atlanta, GA, underscored the significant impact of influenza virus infections on agricultural workers and their families across the Americas, including the United States. Researchers from a rural agricultural community in southwest Guatemala evaluated the incidence and impact of influenza among essential food production workers and their households, emphasizing the broader implications for public health, food security, and economic stability throughout the region.¹

Study Design and Surveillance Methods

To estimate the burden of influenza infection in a rural Guatemalan community, the investigators conducted active surveillance among 170 households from January 2023 through August 2024. They implemented twice-weekly monitoring for influenza-like illness (ILI)—defined as at least 1 day of fever plus cough or sore throat—to ensure prompt case identification. If participants had respiratory symptoms, respiratory swab specimens were collected and tested for influenza by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) on the Roche Cobas Liat platform. Vaccination status information was recorded by the researchers; vaccination data for agricultural workers were collected at the time of vaccine administration, whereas household members’ information was collected retrospectively through self-report.¹

Key Findings: Influenza Incidence and Seasonality

A total of 247 ILI cases were reported during the study period—112 in 2023 and 135 in 2024—with 95 (38%) testing positive for influenza. Among confirmed cases, 84% were caused by influenza A and 16% by influenza B viruses. The influenza incidence rate was 3.0 per 1000 person-weeks (PW) in 2023 (95% confidence interval [CI]: 2.2–4.2) and 3.3 per 1000 PW in 2024 (95% CI: 2.4–4.4). Influenza A incidence rates were 2.6 and 2.8 per 1000 PW in 2023 and 2024, respectively, while influenza B incidence rates were 0.5 and 0.6 per 1000 PW.²

The evaluation indicated that there were no major differences in the frequency of the condition according to age or sex, which implies that the susceptibility was generally distributed among demographic groups. To highlight one point, the flu activity was at its highest level between April and July, when 89% of the 2023 cases and 96% of the 2024 cases were reported. The seasonality of the disease is consistent with the pattern of the influenza virus circulation in the Central American region, where weather conditions and the farm work calendar are usually coinciding with the periods of virus transmission peak.²

Vaccination Gaps and Preventable Illness

The vaccination coverage among the study cohort was almost negligible. Just 3% of cases of influenza indicated that they had been vaccinated during the year before the disease, whereas 97% were not vaccinated. These results point to the continued obstacles that exist against the rural and farming community's vaccine uptake, obstacles that could be limited access to healthcare services, vaccine hesitancy, and lack of employer-supported immunization initiatives.³

One of the major public health concerns is that vaccination coverage among agricultural workers is still poorly recognized. Research has indicated that regular immunization may reduce influenza-related absenteeism, increase productivity, and lower the spread of infection at home, particularly in those communities where the members of the families live in close quarters and are reliant on seasonal income.²

Conclusion

This longitudinal research is among the very first detailed accounts that meticulously quantify the influenza burden of the agricultural household in Central America. The results show that influenza—mostly influenza A—is still a major and underaddressed problem that is threatening to the communities critical to food security. With low vaccination coverage and consistent seasonal peaks, influenza prevention in these populations represents both a public health necessity and an economic imperative. The researchers emphasized that the money spent on tailor-made vaccination programs for farm workers would be well spent, as it would not only protect their health but also ensure productivity and make the food supply system more stable and reliable in America.^2,3

REFERENCES

1. Lamb M, Carreon D, Adams B, Rojop NC, Calvimontes M, Bradley C, et al. P-203: Incidence of Influenza in Agricultural Workers: The Agricultural Worker COVID-19 Asymptomatic and Symptomatic Transmission in the Home and Workplace (AGRI-CASA) Study, 2023-2024 Presented: IDWeek 2025; October 21, 2025; Atlanta, Georgia. Accessed October 30, 2025 via IDWeek’s online conference platform.

2. Carreon JD, Lamb MM, Chard AN, et al. SARS-CoV-2 secondary attack rates and risks for transmission among agricultural workers and their households in Guatemala, 2022-2023. IJID Reg. 2025;16:100676. Published 2025 May 27. doi:10.1016/j.ijregi.2025.100676

3. Biddle JE, Nguyen HQ, Talbot HK, et al. Asymptomatic and mildly symptomatic influenza virus infections by season -- Case-ascertained household transmission studies, United States, 2017-2023. Preprint. medRxiv. 2024;2024.07.17.24310569. Published 2024 Jul 18. doi:10.1101/2024.07.17.24310569