Epidemiological assessment of SARS-CoV-2 reinfection.

OBJECTIVES: SARS-CoV-2 vaccination has been shown to reduce infection severity; however, the reinfection frequency among unvaccinated, partially vaccinated, and fully vaccinated individuals remains unclear. This study aims to elucidate the rates of and factors associated with such occurrences. METHODS: This retrospective epidemiological report included 1362 COVID-19 reinfection cases in Bahrain between April 2020 and July 2021. We analyzed differences in disease severity and reinfection characteristics among various vaccination statuses: fully vaccinated, interrupted vaccination, one-dose vaccination, postreinfection vaccination, and unvaccinated. RESULTS: Reinfection cases increased from zero per month in April-June 2020 to a sharp peak of 579 in May 2021. A significantly larger proportion of reinfected individuals were male (60.3%, P <0.0001). Reinfection episodes were highest among those 30-39 years of age (29.7%). The fewest reinfection episodes occurred at 3-6 months after the first infection (20.6%) and most occurred ≥9 months after the initial infection (46.4%). Most individuals were asymptomatic during both episodes (35.7%). Reinfection disease severity was mild, with vaccinated patients less likely to have symptomatic reinfection (odds ratio 0.71, P = 0.004). Only 6.6% of reinfected patients required hospitalization. One death was recorded; the patient belonged to the unvaccinated group. CONCLUSION: Vaccine-induced immunity and previous infection with or without vaccination were effective in reducing reinfection disease severity.

Safety and Immunogenicity of COVID-19 BBIBP-CorV Vaccine in Children 3-12 Years Old.

BACKGROUND AND OBJECTIVES: In the current COVID-19 pandemic, children below the age of 12 could manifest COVID-19 symptoms and serve as a reservoir for the virus in the community. The present study was conducted to evaluate the reactogenicity, and immunogenicity of BBIBP-CorV, prior to involving this age group in the vaccination program in the kingdom of Bahrain. SUBJECTS AND METHODS: The study included 582 children from 3 to 12 years old of Bahraini and non-Bahraini nationality, all of which contributed to the reactogenicity study. Of those, 401 contributed to the immunogenicity study. All children received 2 doses of BBIBP-CorV inactivated virus 3 weeks apart. To assess reactogenicity, children were followed up for 5 weeks to evaluate any vaccine-related adverse events (AE). To assess immunogenicity, blood was collected on day 0 and day 35 to assess antibody titer against S, N, and neutralizing antibody. RESULTS: Of the 582 participants, (45.4%) were female, (54.61%) were male, with 49% in 9-12 age group. Of the 401 children contributing to the immunogenicity study, 274 (68.3%) had no prior exposure to COVID-19. The overall incidence of AE was 27.7%. No significant difference was found among different age groups. The most frequent AE was local (at the injection site) and occurred in 16% of children, followed by fever in 9.3%. No serious adverse events were reported. The Seroconversion rate was 100% among children with no prior exposure to COVID-19. Children with previous COVID-19 exposure had higher averages of anti-S (2379 U/mL compared to 409.1), anti-N (177.6 U/mL compared to 30.9) and neutralizing antibody (93.7 U/mL compared to 77.1) than children with no prior exposure at day 35. CONCLUSIONS: Two doses of COVID-19 BBIBP-CorV on the subjects aged between 3 to 12 has good safety and tolerance and can induce an effective immune response and neutralizing antibody titer.

The effect of ABO blood group and antibody class on the risk of COVID-19 infection and severity of clinical outcomes.

The COVID-19 pandemic has affected more than 100 million cases and caused immense burdens on governments and healthcare systems worldwide. Since its emergence in December 2019, research has been focused on treating the infected, identifying those at risk and preventing spread. There is currently no known biological biomarker that predicts the risk of infection. Several studies emerged suggesting an association between ABO blood group and the risk of COVID-19 infection. In this study, we used retrospective observational data in Bahrain to investigate the association between ABO blood group and risk of infection, as well as susceptibility to severe ICU-requiring infection. We found a higher risk associated with blood group B, and a lower risk with blood group AB. No association was observed between blood group and the risk of a severe ICU-requiring infection. We extended the analysis to study the association by antibodies; anti-a (blood groups B and O) and anti-b (blood groups A and O). No association between antibodies and both risk of infection or susceptibility to severe infection was found. The current study, along with the variation in blood group association results, indicates that blood group may not be an ideal biomarker to predict risk of COVID-19 infection.

The high prevalence of asymptomatic SARS-CoV-2 infection reveals the silent spread of COVID-19.

PURPOSE: The COVID-19 pandemic has led to over 92 million cases and 1.9 million deaths worldwide since its outbreak. Public health responses have focused on identifying symptomatic individuals to halt spread. However, evidence is accruing that asymptomatic individuals are infectious and contributing to this global pandemic. METHODS: Observational data of 320 index cases and their 1289 positive contacts from the National COVID-19 Database in Bahrain were used to analyze symptoms, infectivity rate and PCR Cycle threshold (Ct) values. RESULTS: No significant difference (p = 1.0) in proportions of symptomatic (n = 160; 50.0%) and asymptomatic index cases (n = 160; 50.0%) were seen; however, SARS-CoV-2 positive contact cases were predominantly asymptomatic (n = 1127, 87.4%). Individuals aged 0-19 years constituted a larger proportion of positive contact cases (20.8%) than index cases (4.7%; p < 0.001). A total of 22% of the positive contacts were infected by symptomatic male index cases aged between 30-39 years. The total numbers of exposed contacts (p = 0.33), infected contacts (p = 0.81) and hence infectivity rate (p = 0.72) were not different between symptomatic and asymptomatic index cases. PCR Ct values were higher in asymptomatic compared to symptomatic index cases (p < 0.001), and higher in asymptomatic compared to symptomatic positive contacts (p < 0.001). No differences between the infectivity rates of index cases with Ct values <30 and values ≥30 were observed (p = 0.13). CONCLUSION: These data reveal that the high asymptomatic incidence of SARS-CoV-2 infection in Bahrain and subsequent positive contacts from an index case were more likely to be asymptomatic, showing the high "silent" risk of transmission and need for comprehensive screening for each positive infection to help halt the ongoing pandemic.

The Efficacy and Safety of Hydroxychloroquine in Patients with COVID-19: A Multicenter National Retrospective Cohort.

INTRODUCTION: Hydroxychloroquine (HCQ) is an antimalarial drug that received worldwide news and media attention in the treatment of patients with coronavirus disease 2019 (COVID-19). This drug was used on the basis of its antimicrobial and antiviral properties despite lack of definite evidence of clinical efficacy. In this study, we aim to assess the efficacy and safety of using HCQ in treatment of patients with COVID-19 who were admitted in acute care hospitals in Bahrain. METHODS: We conducted a retrospective cohort study on a random sample of patients admitted with COVID-19 between 24 February and 31 July 2020. The study was conducted in four acute care COVID-19 hospitals in Bahrain. Data was extracted from the medical records. The primary endpoint was the requirement of non-invasive ventilation, intubation, or death. Secondary endpoint was length of hospitalization for survivors. Three methods of analysis were used to control for confounding factors: logistic multivariate regression, propensity score adjusted regression, and matched propensity score analysis. RESULTS: A random sample of 1571 patients were included, 440 of whom received HCQ (treatment group) and 1131 did not receive it (control group). Our results showed that HCQ did not have a significant effect on primary outcomes due to COVID-19 infection when compared to controls after adjusting for confounders (OR 1.43, 95% CI 0.85-2.37, P = 0.17). Co-administration of azithromycin had no effect on primary outcomes (OR 2.7, 95% CI 0.82-8.85, P = 0.10). HCQ was associated with increased risk of hypoglycemia (OR 10.9, 95% CI 1.72-69.49, P = 0.011) and diarrhea (OR 2.8, 95% CI 1.4-5.5, P = 0.003), but not QT prolongation (OR 1.92, 95% CI 0.95-3.9, P = 0.06) or cardiac arrhythmia (OR 1.06, 95% CI 0.55-2.05, P = 0.85). CONCLUSION: Our results showed no significant beneficial effect of using hydroxychloroquine on the outcome of patients with COVID-19. Moreover, the risk of hypoglycemia due to hydroxychloroquine would possess a significant risk for out-of-hospital use.