SARS-CoV-2 Infection among Students at a High School, Mashonaland West, Zimbabwe, December, 2020

Abstract

Introduction: COVID-19 continues to be a major public health problem globally. On December 1, 2020, nine students at a high school presented at the school clinic with flu-like symptoms. COVID-19 was suspected and nasopharyngeal swabs were collected. The nine samples tested positive for SARS-CoV-2 on Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) test. From the first to the 8th of December 2020, the attack rate increased from 2.6% to 29.8%. We described the outbreak by person, place and time and determined factors associated with the outbreak at the school. Methods: We conducted a retrospective cohort study. A student or staff member at the school who had undergone RT-PCR, SARS-CoV-2 testing was recruited into the study. Data were collected using a pretested questionnaire, checklists and observations. Means, medians, frequencies, risk ratios, adjusted risk ratios and their corresponding 95% CI were calculated using Epi Info 7. We used the same software to construct an epidemic curve. We calculated student density in classrooms and dormitories and determined the relationship between student density and attack rates. Results: The overall COVID-19 attack rate among the 340 recruited participants was 31.8 %. Sharing utensils with a confirmed case (aRR=6.47, 95% CI: 2.97-14.1) and being in contact with a positive case within 1 metre in the past 7 days (aRR=17.2, 95% CI: 7.42-39.9) were independent risk factors associated with contracting SARS-CoV-2 infection. Owning and using a personal hand sanitizer (aRR=0.04, 95%CI: 0.02-0.10) and consistency in hand washing (aRR=0.16, 95%CI: 0.07-0.33) were protective factors. The mean student density was 2.8m2 (Min1.5, Max 3.0) classrooms and 3.1 m2 (Min 2.5, Max 3.9) in dormitories. There was a negative linear relationship between average bed spacing and attack rates of COVID-19 in hostels. Conclusion: Sharing of utensils or belongings and being in contact with a COVID- 19 case were risk factors for the outbreak. Overcrowding in the classrooms and dormitories fuelled the spread of the virus. We prohibited sharing of utensils, increased hand washing facilities with soap and reduction of the number of new intakes of form 1 and 5 students for 2021. Bed spacing in the dormitories was adjusted so that each student occupies the recommended 3.75m2/student.