The dynamics of COVID-19 epidemic in Basrah province-Second report

Introduction

COVID-19 still represents a threat to the health of the population in Basrah despite the efforts to contain the spread of infection at community level. The epidemiology of the disease is evolving and the complete picture is not complete yet at local and global levels. ^{1 , 2} In our previous article ¹ on COVID-19 in Basrah which covered cases reported from February 24 to April 10, 2020 we stated that the scale of COVID-19 epidemic was modest in Basrah and may continue as such for a period of time. Since then, the time trend remained moderate and the distribution across various administrative units of the province has relatively changed with variable risk became evident in these units. Active case detection among contacts of notified cases revealed a number of clusters of undetected cases. In one place (Khura in Hartha district) the number of positive contacts detected was 37. The characteristics of detected cases might have changed as active surveillance revealed a tangible number of asymptomatic contacts. However the overall situation remained under control and no panic has occurred. The health authorities are enforcing every protective measure possible and the preparedness to accommodate increasing numbers who need hospital admission or quarantine is well maintained. However, the measures against the COVID-19 epidemic in the foreseeable future may need extensive reconsideration to encompass not only health aspects but also the consequences of the epidemic on population living and country economics. ³ In order to update the epidemiological situation in Basrah and keep up with further development, we present further details on the characteristics of the affected persons and specific outcomes, eg., incidence rate, case fatality ratios and others, as of May 20, 2020. Also a further add on time trend of the epidemic curve is updated to encompass the period from March 9 to May 20, 2020.

Method

Cases of COVID -19 are notified in Basrah and Iraq on the basis of single criteria; a case denotes a person with a positive nasal or oral swab Polymerase Chain Reaction Test (PCR). The triggers for the test were clinical features suggestive of the disease, contact with cases and history of an event of travel to other affected countries. The data used in this article are totally obtained from the official records of the epidemiological Unit at the Department of Public Health in Basrah. ⁴ An excel sheet was received covering reported cases in Basrah from March 9 to May 20, 2020. The sheet contained details related to age, gender, date of diagnosis, residence (administrative unit and quarter), type of case (passive or active detection), any travel history, presence of comorbidity (no details were obtained) and fate of patient (cured, died or under treatment). The data were imported into a statistical programme (Statistical Package for Social Science-SPSS-Version 20) for statistical analysis. These data were used for describing demographic characteristics (age, gender, residence) and outcome measures (incidence rate, case-fatality ratio and fate). For the description of the time trend of the epidemic (epidemic curve) the daily numbers covering the period from 9 March to 20 May, 2020two sources were used. A complete inventory which was made by the authors since the start of the epidemic. This inventory contained the daily reported cases and was based on the data available with Department of Public Health in Basrah and the daily report of the Ministry of Health. Verification and consolidation of reported cases were made by consulting the weekly situation reports issued by the Ministry of health ^{5 - 8} and a number of international data generating websites. ^{9 - 11} The latter were used as indirect validation of reported data. Information on population of Basrah province and the nine sub-districts b (sectors) was based on estimates made by the Ministry of Planning and available at the Department of Public Health in Basrah. ¹²

For the purpose of this article the following definitions were used. ⁹

Closed case: A case that has an outcome (Cured or died)

Incidence rate: The number of reported cases per 1000000 populations up to the designated date.

Case fatality ratio for all cases: Number of deaths among COVID-19 reported cases up to the designated date divided by all reported cases over the same period (as percentage).

Case fatality ratio for closed cases. The number of deaths among COVID-19 cases reported up to the designated date divided by summation of deaths and recoveries over the same time period (as percentage).

Basrah province: refers to the official area and population as defined by legal system in Iraq.

The data were transferred from an excel sheet into the Statistical Package for Social Science-Version 20 for the purpose of tabulation and statistical analysis Chi-squared (Or Fisher Exact Test) were used to explore associations in case of qualitative data. Excel functions were used to prepare the required figures. Means were calculated by suitable function of the SPSS.

Results

The article presents data on 736 cases of COVID-19 infection reported in Basrah province over the period from March 9 to May 20 2020.

Age and gender

(Table-1) shows the distribution of COVID-19 cases according to age and gender. The mean age ± SD was 35.5 ± 18.9 years (for males = 35.6 ± 19.0 and for females = 35.5 ± 18.8), the median was 34 years (males = 34 and females = 33). The two gender groups exhibited similar age pattern and overall age distribution was not statistically different between genders (P = 0.521).

Residence, travel history and co-morbidity

Table 2 shows that during the period from March 9 to May 20, 2020, most of the COVID-19 cases were reported from Basrah city (44.4%), Hartha district (25.8 % and Mdaina district (11.7%). Only 8 (1.1%) reported travel history outside Basrah province. Of the total cases, 96 (13.0%) had co-morbidity and as on May 20, 2020, 270 (36.7%) were cured, 18 (2.4) died and the remaining 446 (60.9%) were under treatment or quarantine.

rates

The extent of risk expressed as incidence rate per million populations according to age, gender and residence is shown in Table 3. With respect to age, the incidence rates increase steadily with advancing age reaching a peak (951.4 per million) at the age of 70 years and above. The incidence rate for females was higher (285.4per million) than for males (208.8 per million). Regarding residence (district), Hartha, Mdaina and Basrah city had the highest incidence rates in that order as compared to other districts. The Overall incidence rate for Basrah province as of May 20, 2020 is 246.6 per million.

Fatality

The case fatality ratio for all cases was very variable across age, gender, residence and co-morbidity groups as shown in Table 4. No death was reported in persons aged less than 30 years and the highest case fatality ratio was in persons aged 70 years and above (20.5 %). Gender-wise the case fatality was higher in male cases but the difference was statistically not significant (P = 0.145). Regarding the district of residence deaths were reported for cases in Basrah city, Abul-Khasib and Shatt Al-Arab districts. No deaths were reported in cases from other districts. The highest case fatality ratio was in Shatt Al-Arab district (9.4%). Presence of co-morbidity carried a significant impact on the risk of death with case fatality ratio being significantly higher (13.5%) among cases with co-morbidity as compared to cases with no co-morbidity (0.8%) The overall case fatality ratio was 2.4% for all cases and 6.3% for closed cases (cases with outcome).

Factors predicting fatality

A logistic regression analysis was done to identify the independent significant predictors of case fatality. The dependent variable was dichotomous whether a person was dead or alive as to May 20. The independent variables were age (continuous), presence of co-morbidity (dichotomous) and district of residence (dichotomous as Basrah city versus others) and travel history (dichotomous). The results are shown in (Table-5). Older age, presence of travel history and co-morbidity predicted high fatality. These three variables are independent significant predictors of case fatality associated with COVID-19 infection in Basrah province. Residencewas not significant predictors of fatal outcome.

Dynamics of the epidemic curve

The time trend of reported daily cases is illustrated as an epidemic curve in Figure 1. Characteristic features can be identified. First, fluctuation of reported cases over time with many peaks and dips in the curve. Second, apart from few days when the numbers are relatively large (e.g., March 27 and April 28 and 29), otherwise the curve is an expression of low scale epidemic throughout the almost nine weeks since the onset of the epidemic in Basrah. The epidemic started as few sporadic cases during the first two weeks then it changed to daily cases throughout the following seven weeks. The epidemic curve for cumulative cases (Figure-2) shows a steady ladder pattern increase in the cumulative cases. The ascending curve is not very sharp but it does not flattened yet.

Figure 1. Daily reported cases of COVID-19 infection in Basrah province over the period from March 9 to May 20, 2020.

Figure 2. Cumulative cases of COVID-19 infection in Basrah province over the period from March 9 to May 20, 2020.

Discussion

The present article complements and builds on our previous publication on COVID-19 in Basrah. ¹ It is important to state here that as the epidemic is still continuing, it is difficult to provide a complete picture of its features and outcome. However, adding more cases and including longer period of time had uncovered new insights about the dynamics of the epidemic in terms of demographic characteristics, geographical distribution and outcome indicators. In general the epidemic in Basrah is still moderate in intensity with characteristic fluctuations in daily reported cases. These fluctuations reflect the practice of active case detection among contacts of reported cases and the nature of cluster transmission of infection. The curve of cumulative cases is showing ascending trend but it is neither exponential nor leveled yet. The demographics of the cases in Basrah revealed two features; the mean and median ages are much lower than the corresponding figures reported in other studies outside Iraq as for example the studies in Singapore, ¹³ China ^{14 , 15}anda higher proportion of children aged less than ten years (7.7% in Basrah compared to 0.9% in China ¹⁴).The higher proportion of children among cases in Basrah is partly due to the fact that children represent about 40% of the general population, ¹⁶ but also suggests that children are susceptible to COVID-19 infection. ² The case fatality ratio for all cases was 2.4% and it seems within the range at the global situation. ^{17 - 19} A fatal outcome was likely if the patient was of old age, with co-morbidity and had travel history prior to the onset of the disease. This result was consistent in both univariate analysis and logistic regression. It is consistent with research from other parts of the world. ^{17 , 20} The relative delay in leveling and descending of the epidemic curve with time could be attributed to the misconception of the public about social distancing and the limited resources available for active case detection. ²¹ Despite that, the exit from the COVID-19 epidemic is feasible given the low scale of apparent cases, the cluster nature of transmission and the informing situation in the country and at global level.

Conclusion

Despite the passage of almost nine weeks since the onset of COVID-19 infection in Basrah, the epidemic curve showed fluctuation with multiple peaks and no clear evidence that an exit is predictable in the coming foreseeable future. The inadequate coverage by testing and the misconception of people about social distancing are likely to keep the epidemic going on for some time in the foreseeable future. However, it is unlikely that the epidemic will escalate in exponential pattern provided that reasonable level of preventive measures is maintained.

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