Background
In July/2021, the Darwin strain of Influenza A (H3N2) virus was identified in Australia. In December/2021, there was an increase of flu syndrome cases among workers from a large meatpacking plant and a hospital in Rio Verde. This study aimed to confirm the existence of an outbreak, to describe the cases and to propose recommendations.
Methods
We carried out a descriptive case series study. We defined a confirmed case as: “worker from the hospital or meatpacking plant in Rio Verde who presented a laboratory test, by RT-PCR, detectable for Influenza A (H3N2), between December 6th and 18th, 2021”. For data collection and analysis, we used a semi-structured questionnaire, and descriptive statistics. Ethical aspects were respected.
Results
We identified 43 suspected cases, and 27 were confirmed for Influenza A (H3N2). We interviewed 25 workers, 17 (68.0%) were from hospital and 08 (32.0%) from meatpacking plant. From hospital, 15 (88.2%) workers were female with a median age of 31 years (Q1-Q3: 28-36); from meatpacking plant, 4/8 were male with a median age of 23 years (Q1-Q3: 21-27). Thirteen (76.5%) hospital workers and 4/8 meatpacking plant workers were vaccinated against Influenza. All workers had symptoms, such as muscle pain (100.0%), cough (94.1%; 83.3%) and nasal obstruction (82.4%; 83.3%), respectively. None were hospitalized and no deaths occurred. Nine (53.0%) hospital workers and 2/8 meatpacking plant workers were working symptomatic. A meatpacking plant worker sample was sequenced and matched to the Darwin strain.
Conclusion
We confirmed the occurrence of Influenza A (H3N2) outbreaks in both institutions. Virus circulation may have been intensified by emergence of the Darwin strain, not included in the vaccine administered in Brazil in 2021. We recommended: implementing respiratory viruses surveillance; maintaining guidelines on preventive measures for workers; intensifying actions for vaccination against Influenza; and reinforcing guidelines regarding medically oriented sick leave for symptomatic workers.