ABSTRACT
Background. Protection offered by five different forms of immunity, combining natural and vaccine immunity, was investigated against symptomatic SARS-CoV-2 infection from Omicron BA.1 or BA.2, and severe, critical, or fatal COVID-19 from BA.1 or BA.2, in Qatar, between December 23, 2021 and February 21, 2022. Methods. Six national, matched, test-negative case-control studies were conducted on a sample of 272,861 PCR-positive tests and 669,628 PCR-negative tests to estimate effectiveness of BNT162b2 (Pfizer-BioNTech) vaccine, mRNA-1273 (Moderna) vaccine, natural immunity due to prior infection with pre-Omicron variants, and hybrid immunity from prior infection and vaccination. Results. Effectiveness of prior infection alone against symptomatic BA.2 infection was 46.1% (95% CI: 39.5-51.9%). Effectiveness of two-dose BNT162b2 vaccination alone was negligible at -1.1% (95% CI: -7.1-4.6), but nearly all individuals received their second dose >6 months earlier. Effectiveness of three-dose BNT162b2 vaccination alone was 52.2% (95% CI: 48.1-55.9%). Effectiveness of hybrid immunity of prior infection and two-dose BNT162b2 vaccination was 55.1% (95% CI: 50.9-58.9%). Effectiveness of hybrid immunity of prior infection and three-dose BNT162b2 vaccination was 77.3% (95% CI: 72.4-81.4%). Meanwhile, prior infection, BNT162b2 vaccination, and hybrid immunity all showed strong effectiveness ( >70%) against severe, critical, or fatal COVID-19 due to BA.2. Similar patterns of effectiveness were observed for BA.1 and for the mRNA-1273 vaccine. Conclusion. There are no discernable differences between BA.1 and BA.2 in the effects of prior infection, vaccination, and hybrid immunity. Vaccination enhances the protection of those with a prior infection. Hybrid immunity resulting from prior infection and recent booster vaccination conferred the strongest protection.
ABSTRACT
Introduction: Contact tracing is an integral component of the overall public health strategy for controlling the outbreak of infectious diseases such as COVID-19. In addition to the conventional contact tracing, Qatar has implemented Ehteraz, a proximity-tracing mobile phone App using global positioning system and Bluetooth technologies. In this paper, we aim to evaluate the accuracy of Ehteraz as a contact tracing App based on the WHO contact tracing criteria and compare its effectiveness to the traditional human led case investigation. Methods: A cross-sectional study was conducted using two databases, including Ehteraz proximity data and swab collection and case investigations reports for the same period. Results: 46.9% of contacts identified by the Ehteraz app did not meet WHO duration and distance criteria. Among the 5650 contacts flagged by Ehteraz during the period, 4973 (88.0%) of contacts did not share any known relation with the index case they are linked to. Conclusion: The study highlighted the inaccuracy of the Ehteraz tool as its technology enables signals passing through walls, so people in different rooms could be unnecessarily flagged as having had contact. Big segments of the population (eg, Children) do not necessarily use smartphones and are not, therefore, flagged by Ehteraz digital contact tracing App. Similarly, Ehteraz rarely flags close contacts identified by human investigation as Bluetooth is usually turned off in a household or at a workplace. These findings highlight that digital contact tracing would be an efficient public health strategy when integrated to and complementing human investigation.
ABSTRACT
Background: Case investigation and surveillance is a key step in managing any epidemic. This report aimed to identify the main challenges faced by COVID-19 case investigators in Qatar and to suggest possible solutions to improve the case investigation process in managing future pandemics. Methods: Purposive sampling was used to select 40 COVID-19 case investigators posted at the Ministry of Public Health, Qatar. Interviewees were from diverse educational and cultural backgrounds and had been investigating COVID-19 cases for more than 6 months, at the time of interview. Face-toface semi-structured interviews were done to collect data which was anonymized before analyzing for the purpose of this qualitative study. Results: The most common concern faced in conducting case investigations was language barrier, given the multinational and diverse diasporas Qatar is host to. Authenticity of the investigation was a matter of suspicion for many patients;whereas the majority of the investigators opined that multiple calls received from different healthcare departments asking for information overwhelmed many patients. Laborers/migrant workers often did not divulge information due to fear of repercussions from their supervisors. Social stigma associated with COVID-191 caused reluctance to reveal the index case and close contacts. Information regarding social gatherings attended and public places visited was often concealed (Figure 1). Cultural differences as well hindered smooth investigation in a few cases. Rising case load at times put restraints on improved coordination between different health departments2 and structured guidance for investigators3 about the pandemic response system, which could help to deliver appropriate health services more efficiently. Comprehensive orientation in using the Electronic Surveillance database could also improve the efficacy of epidemiological analysis for improved public health outcomes. Conclusion: Addressing these challenges will help the public health team in Qatar to increase preparedness and efficiency in managing potential future outbreaks, especially in view of upcoming mass gathering events such as the FIFA 2022 World Cup.
ABSTRACT
Background: After a long, unprecedented pause, sporting events were cautiously resumed in Qatar in September 2020. With the persisting COVID-19 uncertainties, characterizing the COVID-19 risks related to sports activities remains to be examined, making it difficult to give clear messages 1. This report describes some of the key challenges and opportunities for communicating COVID-19 risks associated with sporting events. Methods: The outbreak investigation report for COVID-19 cases related to the Asian Federation Cup (AFC) Champions League-West hosted in Qatar Sep 14th to Oct 3rd, 2020 was interpreted and taken as a case study. Results: The outbreak investigation reports, which involved approximately 74 COVID-19 cases is shown in Figure 1 and constituted the main subject to communicate the risks of the infection. The investigation teams were engaged in person-to-person communication, reviewing the history of the possible risk exposure and explaining the recommended measures. Clubs' physicians and delegations besides the local organizing committee seem to have played a pivotal role as a credible source of information to the players and media about the possible case scenarios and the control measures2,3. The yet unclear mode of transmission may have contributed to the poor risk perception and the compliance with the unfamiliar preventive recommendations2,3. Conclusion: The profound evolution of the pandemic has already offered a unique opportunity to overcome the 'lack of attention' in the communication of communicable diseases. Using the epidemiological findings to communicate COVID-19 risks during sporting events seemed to be beneficial to explain the virus characteristics, emphasizing the role of the epidemiological approaches to improve the risk perception and the compliance with the public health advice.