Validation of rapid antibody (IgG-IgM) test kit for SARS-CoV-2 infection in Qatar.

BACKGROUND: In response to the growing coronavirus disease 2019 (COVID-19) pandemic and the shortage of laboratory based molecular testing capacity and reagents, multiple diagnostic test manufacturers have developed rapid and easy to use devices to facilitate testing outside laboratory settings. These kits are either based on detection of proteins from SARS-CoV-2 virus or detection of antigen or human antibodies generated in response to the infection. However, it is important to understand their performance characteristics and they must be validated in the local population setting. DESIGN AND METHODS: The objective is to assess the validity of the rapid test for IgG and IgM immunoglobulins compared to the current gold standard reverse transcription polymerase chain reaction (RT-PCR) test. A total of 16951 asymptomatic individuals were tested by the Ministry of Public Health track-and-trace team using both rapid immunodiagnostic test and RT-PCR as part of screening across various random settings with potential risk of community interaction prior to gradual lifting of restrictions in Qatar.  Rapid test was considered to be posiive if both IgG and IgM are positive, while only IgG/IgM positive was considered as rapid test negative. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. RESULTS: The sensitivity of rapid test kit was found to be 0.9%, whereas the specificity was found to be 97.8%. the PPV was found to be 0.3% whereas the NPV was found to be 99.4%. CONCLUSIONS: Based on the outcome and results of the study, it appears that the sensitivity and PPV of the rapid antibody test are low. As such, this test is not recommended for use to assist in taking clinic-based decisions or decisions related to quarantine/isolation.

Bordetella pertussis: An agent not to be forgotten in Qatar.

BACKGROUND: Pertussis (whooping cough) is a vaccine-preventable disease caused by the bacterium Bordetella pertussis that is spread by airborne respiratory droplets. Clinical symptoms vary from infants to adults and are most contagious before the onset of symptoms. Infants are at the highest risk of infection, especially before they are old enough to receive at least two doses of pertussis-containing vaccine. There have been no indigenous cases of pertussis in Qatar since 2010 until 2018, due to free pertussis-containing vaccines under the National Immunization Schedule of Qatar, with coverage consistently above 95%. Two cases were reported in 2016 but were found to be imported. In 2019, 20 infants were reported as suspected pertussis to the Health Promotion and Communicable Disease Control (HP-CDC), Ministry of Public Health (MOPH), Qatar; of them, five were laboratory confirmed as pertussis. OBJECTIVE: This study aimed to describe the five confirmed cases of pertussis reported to HP-CDC, MOPH, Qatar, between January 1 and December 30, 2019. Summary of Cases: All five confirmed pertussis cases were under one year old, and three were boys. All except one were immunized-for-age, and three had not received any doses of pertussis-containing vaccine and in none of the cases had the mother received tetanus, diphtheria, and acellular pertussis (Tdap) vaccine during pregnancy. All infants were born in Qatar, and two were Qatari nationals. CONCLUSION: There may be a possibility of re-emergence of pertussis in Qatar. Active immunization and coverage maintenance are the best tools to prevent re-emergence. Undiagnosed and untreated pertussis cases are potential sources of infection. The partial or unimmunized groups may be significantly at risk, especially during infancy and before reaching the age to complete the three primary doses of diphtheria, tetanus, and pertussis vaccines. Focus on increasing awareness among those providing antenatal care, regarding the importance of Tdap vaccination during pregnancy, is necessary.

Can the cycle threshold (Ct) value of RT-PCR test for SARS CoV2 predict infectivity among close contacts?

BACKGROUND: COVID-19 global pandemic is an unprecedented health emergency. Rapid identification and isolation of infected individuals is crucial. Qatar's National Health Strategic Command Group adopted a cut off 30 for Ct value of RT-PCR result of a positive case to decide on duration of isolation and quarantine period for their close contacts. AIM: To test if Ct value cut off 30 reflects on the infectivity potential among close contacts. METHODOLOGY: All positive cases reported during July' 2020 whose contacts had been traced and swabbed were extracted from database after removing personal identifiers. Close-contact was defined as anybody who has been within 2 m distance of a confirmed positive case for 15 min or more, without any personal protection equipment. Descriptive analysis was done and test of significance of difference in positivity among the contacts of those with ct < 30 and >30 was done. RESULTS: 2308 COVID-19 positive cases were followed up. More than three-quarters had a Ct value < 30, with a mean Ct value of 24.05(+6.48). On an average 6 contacts were swabbed per case. More than half the positive cases followed up had at least one secondary case, with median positivity rate 12.5%. A significant relation was noted between Ct value cut-off 30 and secondary transmission (1.5 times more risk among those with Ct value < 30). A significant difference was noted in median positivity rate between close contacts of positive cases with Ct value > 30 or <30. CONCLUSION: Further studies combining PCR assays, culture studies and contact tracing are needed to define which factors can be used to reliably predict the infectious status of patients with COVID-19.

Sleep and sleepiness during an ultra long-range flight operation between the Middle East and United States.

This study provides a practical example of fatigue risk management in aviation. The sleep and sleepiness of 44 pilots (11 trips × 4 pilot crew) working an ultra long-range (ULR; flight time >16 h) round-trip operation between Doha and Houston was assessed. Sleep was assessed using activity monitors and self-reported sleep diaries. Mean Karolinska Sleepiness Scores (KSS) for climb and descent did not exceed 5 ("neither alert nor sleepy"). Mean daily sleep duration was maintained above 6.3h throughout the operation. During in-flight rest periods, 98% of pilots obtained sleep and sleepiness was subsequently reduced. On layover (49.5h) crew were advised to sleep on Doha or Universal Co-ordinated Time (UTC), but 64% slept during the local (social) night time. Pilots originating from regions with a siesta culture were more likely to nap and made particularly effective use of their daytime in-flight rest periods. The results indicate that the operation is well designed from a fatigue management perspective.