COVID-19 Outbreak Investigation in a boarding school, Marondera district, Mashonaland East Province, Zimbabwe, 2020: A case-control study

Farai Josphas Chitiyo¹, Paul Farai Matsvimbo², Tsitsi Juru^1,&, Emmanuel Govha¹, Notion Gombe³, Mufuta Tshimanga¹

 

¹University of Zimbabwe, Department of Primary Health Care Services, Harare Zimbabwe, ²Zimbabwe Ministry of Health and Child Care, Mashonaland East Province, Zimbabwe, ³African Field Epidemiology Network (AFENET)

 

 

^&Corresponding author
Tsitsi Juru, University of Zimbabwe, Department of Primary Health Care Services, Harare Zimbabwe. tsitsijuru@gmail.com

 

 

 

 

In December 2019, the newly identified severe acute respiratory syndrome coronavirus 2 ( SAR-Cov-2), emerged in Wuhan, China causing Corona Virus Disease of 2019 (COVID-19), a respiratory disease presenting with fever, cough and often pneumonia [1]. As of the 25th of January 2021, COVID-19 had been diagnosed globally in 104 million people with 2.27 million deaths. Southern Africa had 1.7 million cases and 48 919 deaths. Zimbabwe had recorded 33 964 cases and 1269 deaths [2].

 

A confirmed case of COVID-19 is a person with laboratory confirmation of COVID-19 infection irrespective of signs and symptoms [3]. COVID-19 spreads mostly from person to person when breathing in droplets from an infected person and by touching eyes, nose or mouth with hands infected with COVID-19 [4].

 

The World Health Organisation (WHO) set the strategic objectives whose overall goal is to stop further transmission of COVID-19 within China and other countries [5]. The government of Zimbabwe adopted the WHO strategic objectives in January 2020 and took immediate action to enhance preparedness to respond to COVID-19 through the development of the National Preparedness and Response plan [6]. The first activities for the preparedness and response plan started on the 24th of January 2020 and the plan was launched in March 2020 [7]. There are nine pillars for the national preparedness and response plan [6].

 

Zimbabwe recorded its first case of COVID-19 on the 21st of March 2020 [2]. A level five lockdown was imposed on the 30th of March 2020 by the president of Zimbabwe as a mitigation measure against the spread of COVID-19. All non-essential business was shut down including the closure of universities and schools. The lockdown affected negatively the economic activity and there was a relaxation of lockdown rules in July 2020 to open up the economy [8]. Standard Operating Procedures (SOPs) were developed to guide schools on how to conduct business in the wake of the COVID-19 pandemic. These SOPs provided a clear and actionable guidance for safe operations through the prevention, early detection and control of COVID-19 in schools [9]. In boarding schools; the SOPs state that schools should establish and fully monitor sick bays. The schools are expected to enforce the wearing of face masks, maintaining of social distance and no sharing of equipment or utensils by learners and teachers [10].

 

After six months of the closure of Zimbabwean schools, the full reopening of schools occured on the 9th of November 2020 [11]. Returning students were screened at the school gates for symptoms of COVID-19 and had temperatures taken. On the 23rd of November 2020, a female student tested positive for COVID-19 after she had presented herself to the school clinic with acute onset of influenza like symptoms. By the 9th of December 2020, 103 positive cases constituting 98 students and five staff members had been confirmed. Contacts of confirmed cases were identified from the classrooms and dormitories and they were put in quarantine dormitories. Students who were contacts and those with flue-like symptoms had COVID-19 tests done and those with positive results were put in isolation dormitories for 10 days. There have been few studies done on COVID-19 outbreak in boarding schools. We determined the factors associated with contracting COVID-19 in the boarding high school.

 

 

Study design and population

 

We conducted a 1:1 unmatched case-control study design at the boarding school in December 2020.

 

Cases: were defined as students and staff who tested positive for COVID-19 using the Polymerase Chain Reaction (PCR) test from the 23rd of November 2020 to the end of the outbreak on the 5th of January 2021 at the High School.

 

Controls: were defined as students and staff who tested negative for COVID-19 using PCR test from the 23rd of November 2020 to the end of the outbreak on the 5th of January 2021 at the High School. The study population were the students and staff members of the school. Line list was generated and treatment records reviewed.

 

Inclusion criteria: was a student or staff member who had PCR testing for COVID-19 between the 23rd of November 2020 and the 5th of January 2021 and were willing to be included in the study.

 

Exclusion criteria: was a student or staff member who did not have a PCR test for COVID-19 between the 23rd of November 2020 and the 5th of January 2021 and those who were not willing to be included in the study.

 

Study setting

 

The High School is a mission boarding school for boys and girls situated in the rural areas of Marondera district. This is in Mashonaland East province in Zimbabwe. The school offers ordinary level and advanced level education for form one to form six. The school has an enrolment of 1190 pupils with the majority of 1110 pupils being boarders and only 80 day scholars. There are 4 different classes for each form of students from one to form six. The boarders reside in the dormitories according to their forms. There were 43 teaching staff and 40 non-teaching staff who resided in the school compound.

 

Sample size

 

Fleiss formula in Stat Cal (Epi Info 7) was used to calculate the sample size using the following assumptions: 95% level of confidence, 80% power, ratio 1:1 for cases and controls, 19% of controls exposed and odds ratio of 2.71. This is based on a study by Doung-Ngern et al (2020) titled Case-control study of the use of Personal Protective measures and risk for SARs Coronavirus 2 infection, Thailand [12]. A minimum sample of 81 cases and 81 controls was calculated. We recruited 82 cases and 82 controls into the study.

 

Sampling

 

Cases were selected from the line list by simple random sampling from the 103 cases. Controls were selected by simple random sampling from the list of 127 negative COVID-19 results.

 

Data collection techniques and tools

 

An interviewer-administered questionnaire was used to obtain information on demographic data, knowledge, attitudes, practices and risk factors for contracting COVID-19. Environmental assessment of the school was done to assess for school compliance to standard operating procedures for reopening of schools using a checklist and observations. We measured the space allocated to each student in the dormitories and classroom by calculating the student density. Contact tracing was assessed using a checklist.

 

Definition of terms

 

Contact: A contact was defined as anyone who during the infectious period of a case lived with or was within two metres of a person who had confirmed COVID-19 for 15 minutes or more of cumulative contact over a 24 hour period, even if a mask was worn during that contact.

 

Dormitory contact: A student who during the infectious period of a case lived with or was within two metres of a student who had confirmed COVID-19 for 15 minutes or more of cumulative contact over a 24 hour period, even if a mask was worn during that contact in the dormitories.

 

Constant sanitizing: The use of alcohol based solutions for hand hygiene when there was contact with surfaces and other individuals.

 

Regular hand washing: Washing of hands with soap and water after contact with surfaces or other students.

 

Sharing of utensils and belongings: Sharing of plates, cutlery and cups in the dining halls, sharing of clothes and stationery.

 

Wearing of face mask: The use of cloth or surgical face mask as a preventative measure against contracting COVID-19.

 

Properly wearing a face mask: The cloth or surgical face mask is used covering both the mouth and the nose always when wearing the face mask.

 

Data Analysis

 

Data was captured and analysed using Epi-info 7 to generate frequencies, proportions, medians, means, standard deviations and odds ratios. Knowledge, practices and attitudes were assessed on a scale. Knowledge was assessed using seven questions with two or less correct answers graded as poor knowledge, three to four correct answers was graded as fair knowledge and five to seven correct answers was graded as good knowledge. The questions were centred on causes, signs and symptoms, transmission, preventative measures and population at higher risk of death from COVID-19.

 

Practices were graded into good practises with four to seven positive answers to the seven practices questions. Practices were graded poor practises with one to three positive answers. The questions centred on wearing of face mask, washing hands and use of hand sanitisers.

 

Attitude was assessed using four questions and three or four positive answers was rated as good attitude against COVID-19. Bad attitude against COVID-19 was rated as having two or less positive answers against COVID-19. The questions centred on attitude towards face masks, hugging and shaking hands. A Chi-squared test was used to determine the differences in knowledge, attitudes and practices towards COVID-19 among cases and controls. Differences of variables between cases and controls with a p-value of less than 0.05 were considered significant. The reproductive rate was calculated by multiplying the average infectious period and the contact rate according to a study on the Estimation of the basic reproduction number by Dharmaratne et al 2020 [13].

 

Average incubation period was calculated from the epicurve as the time from peak of cases and time of the minimum incubation period from the earliest case reported. Bivariate analysis was done to determine associations between risk factors and contracting COVID-19. Logistic regression analysis was performed to identify independent factors associated with contracting COVID-19 at a 95% Confidence Interval.

 

Student density in classrooms was calculated by dividing the average floor surface area of classrooms by the average number of students in the classroom. For allocated floor space in the dormitories the average floor surface area of the cubicles in the dormitories divided by the average number of students in the cubicle. The recommended space/person density in dormitories according to the Bylaws of Zimbabwe is 3.75m²/student [14]. Any density more denser than 3.75m²/student was regarded as overcrowding.

 

Contact tracing was assessed using a checklist. The checklist included finding the total number of COVID-19 contacts, number of contacts traced, number of contacts monitored, number of contacts isolated or quarantined, number of contacts investigated and health outcomes of contacts.

 

Ethical Considerations

 

This was an outbreak investigation and consent to do the investigation was obtained from the headmaster. The students below 18 years signed an assent for the investigation in the presence of school teachers. Some students whose parents were available gave written consent for the investigation. Adult staff members gave written consent for the investigation. Confidentiality was assured. The aim of the study was explained and the participants were informed that they were free to withdraw at any time during the interview. No names of participants were written on the questionnaire during data collection.

 

 

Descriptive Epidemiology

 

A total of 82 cases and 82 controls were interviewed. Students were mainly affected 77/82(94%) with pupils in form one being the most affected 69/77 (89%) Table 1. There was a gradual rise in cases with the peak of cases occurring on the 3rd of December 2020 (n=19) showing a propagated pattern Figure 1. The average incubation period from the epicurve was 11days. Students in form one red (n=28) and form one green (n=26) were mostly affected by COVID-19. The student density in the classrooms was 0.67m²/pupil. Girls in Sunshine dormitory for form one (n=34) were mostly affected. Form one boys staying in South dormitory (n=25) were mostly affected and each student had a space density of 2.2m²/pupil in the dormitories. There was erratic supply of water at the school and no health inspection had been done prior to the opening of the school.

 

Knowledge, practices and attitudes

 

The study participants were knowledgeable about COVID-19 with the majority 68/82(83%) of the cases and 75/82(92%) of the controls rated as having good knowledge (ƛ2 =2.39; p=0.12). All participants knew about COVID-19 with cases at 82/82(100%) and controls at 82/82(100%). Knowledge of cause of COVID-19 for the cases was78/82(95%) and all the controls 82/82(100%) knew the cause of COVID-19.

 

Overall practice against COVID-19 for the cases was good as just above half of the participants 44/82(54%) had good practice against COVID-19. For the controls, more than three quarters 65/82 (79%) have good practices against COVID-19. More than three quarters of cases 65/82(79%) wash hands sometimes and for controls 52/84(64%) wash hands sometimes. There was a significant difference between the practice of controls and cases against COVID-19 (ƛ2 =11.72; p< 0.05), with the controls having good practices against COVID-19.

 

Overall attitudes of the cases against COVID-19 were good 61/82 (74%) with one-quarter of the cases 21(26%) having bad attitudes against COVID-19. Among the cases the majority 75/82(91%) thought the face masks protect from COVID-19 and 67/82(82%) of the controls thought face masks protect from COVID-19. There was no significant difference in the attitudes of cases and controls against COVID-19 (ƛ²=0.26; p= 0.61).

 

Analytical Epidemiology

 

Bivariate analysis

 

Significant risk factors for contracting COVID19 were contact with a confirmed case of COVID-19 (OR=2.81 95% CI 1.24-6.36); Dormitory contacts (OR=2.79 95% CI 1.46-5.36); Sharing utensils or belongings (OR=3.56 95% CI 1.48-8.53). Significant protective factors against contracting COVID-19 were having a personal hand sanitiser (OR=0.22 95% CI 0.10-0,48); washing hands with soap and water (OR=0.23 95% CI 0.12-0.46) and properly wearing a face mask (OR=0.19 95% CI 0.08-0.45) Table 2.

 

Multivariate analysis

 

Sharing utensils and belongings with a confirmed COVID-19 case was identified as an independent risk factor for contracting COVID-19. (AOR= 4.01 95% CI 1.56-10.31) Table 3.

 

Reproductive number (R0)

 

There were 103 cases with assumed 103x4= 412 contacts.

 

All the cases recovered making y=103

 

 

The reproductive number is 4

 

Assessment of contact tracing

 

Twenty of the students who escaped from quarantine subsequently had positive results for COVID-19. Only three students had their contacts traced. Ten contacts were traced and COVID-19 tests done on them were negative. At the school the contacts were put in quarantine. However, not all the contacts were identified and listed within 24 hours.

 

 

The study sought to determine the risk factors for contracting COVID-19 at the high school. The students were overcrowded in the classrooms and dormitories. Sharing of utensils and belongings with a confirmed case of COVID-19 was an independent risk factor for contracting COVID-19.

 

The distribution of cases over time suggested propagated outbreak with person-to-person transmission affecting mostly form one students who were overcrowded. The environment was conducive for the rapid spread of the of the virus as students learned in close proximity. In our study, the form one students in the classrooms had an average student density of 0.67m ²/ student. The recommendation in a study by Tanner et al (2009) on minimum classroom size and number of students per classroom is for students to have a student density of 1.5m²/ student [15]. Our findings are similar to a study by Stein-Zamir (2020) who reported overcrowding in the classrooms with 1,1 to 1,3m²/student [16].

 

Having someone in the dormitory with signs suggestive of COVID-19 was a risk factor associated with acquiring COVID-19 infection. In our study, overcrowdedness was noted among the students in the dormitories. According to the education statutory instrument 24 of 1980, the recommendation is for each student in a dormitory to occupy an area of 3.75 square metres [14]. The students live in close proximity and infectious illness can spread easily from person to person due to overcrowdedness. The findings are supported by a study by Ng et al (2020) who reported that sharing a bedroom was associated with COVID-19 transmission among household contacts [17]. The increased risk of transmission might be because of closer and prolonged interactions during the night. These findings are similar to Madewell et al (2020) who reported crowded indoor environments such as households as high-risk settings for the transmission of COVID-19 [18].

 

The environmental inspection done in our study showed there was no constant supply of running water, no handwashing facilities at entrances and no bins in every classroom.There will be no water for washing hands and the school will be unhygienic leading to more transmission of COVID-19 infection.Similar to our findidngs, Rozenfeld et al in the USA (2020) in a study showed that in general population risk factors like low air quality, poor hygienic conditions and poor housing were at higher risk for contracting COVID-19 [19].

 

We also found students who shared utensils and belongings were at higher risk of contracting COVID-19. Students share materials as they live in a community and this allows transmission of the infection. The spread of infection from person to person may include touching infected objects or surfaces then touching their nose, mouth or eyes. Our findings are similar to findings by Cirrincione et al (2020) who found that there was a risk of transmission of COVID-19 to individuals through contact with infected subjects, objects, equipment or contaminated environmental surfaces [20]. Contrasting findings by Doung-Ngern et al (2020) in a case-control study who reported no significant risk for COVID-19 infection among persons sharing dishes or cups [12]. The differences may be due to disinfection of surfaces leading to less transmissibility of COVID-19.

 

We also found out that contact tracing was not done on the majority of students who escaped from quarantine. This was a missed opportunity to prevent the spread of COVID-19 to contacts. There is a need to track the infected to ensure they do not spread the disease further. Contact tracing is key to control the spread of COVID-19. A study by Ng et al (2020) found that extensive contact tracing for every diagnosed COVID-19 case with enforced quarantine and intensive health surveillance of close contacts provided an opportunity to determine asymptomatic attack rates and reduce transmission of COVID-19 [17].

 

The study participants had good knowledge of COVID-19. Messages of COVID-19 were widely available and students and staff found the information from social media, newspapers, the internet, radio and television. The findings are supported by Ding et al (2020) in a study who reported that college students had high knowledge of COVID-19 disease [21]. Similar findings by Soltan et al (2020) whose study on college students reported good knowledge on COVID-19 [22]. The good knowledge will enhance practicing preventative behaviours to control the spread of COVID-19.

 

Limitations

 

Our study had some limitations. Recall bias may have occurred as the cases remember and report their exposure experiences differently from the controls. This could have lead to either an overestimation or underestimation of the association between exposures and COVID-19. The participants were given enough time to remember exposures that had occurred. Social desirability responses bias is likely, especially regarding the attitudes and practices questions. The bias was minimised by having the interviews in a non-judgemental atmosphere and guaranteeing the confidentiality of responses. The are chances of misclassification of cases and controls. The use of controls with negative COVID-19 test results may have limited the misclassification and controls who became symptomatic were encouraged to be retested.

 

 

Sharing of utensils and belongings amongst students and overcrowding in the classrooms and dormitories were the risk factors for this outbreak. The outbreak was propagated and students in form one were mainly affected by COVID-19.

 

Recommendations

 

We recommended PCR COVID-19 testing of students when the school reopens again and the school to have adequate water for hand hygiene. We also recommended the reduced intake of form one and form five for the year 2021 to 38 students per class. The school to provide hand sanitisers for students. We also recommended quarterly school health inspections and to strengthen and capacitate contact tracing in school outbreaks by the rapid response health team. There was immediate closure of the school for non-examination classes to decongest the school.

 

 

The authors declare no competing interests.

 

 

FJC, PFM: Conception of the problem, design, data collection, data analysis and interpretation,manuscript writing. TJ,EG, NG, MT: Conception of the problem, design, data analysis and interpretation, critical revision and final approval. All authors read and approved the final manuscript.

 

 

We would like to acknowledge the contributions made by Mashonaland East provincial health executive, Marondera district health executive, the school clinic staff, the school administration, the study participants and the health studies office for all the assistance.

 

 

Table 1: Demographic characteristics of cases and controls in a Zimbabwe High School, 2020

Table 2: Risk factors associated with contracting COVID-19 in a Zimbabwe High School, 2020

Table 3: Independent risk factors associated with contracting COVID-19 in a Zimbabwe High School, 2020

Figure 1: Epidemic curve for COVID-19 outbreak in a boarding school, Zimbabwe, 2020

 

 

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