RESUMO
We investigate differences in protection from previous infection and/or vaccination against infection with Omicron BA.4/5 or BA.2. We observed a higher percentage of registered previous SARS-CoV-2 infections among 19836 persons infected with Omicron BA.4/5 compared to 7052 persons infected with BA.2 (31.3% vs. 20.0%) between 2 May and 24 July 2022 (adjusted odds ratio (aOR) for testing week, age group and sex: 1.4 (95%CI: 1.3-1.5)). No difference was observed in the distribution of vaccination status between BA.2 and BA.4/5 cases (aOR: 1.1 for primary and booster vaccination). Among reinfections, those newly infected with BA4/5 had a shorter interval between infections and the previous infection was more often caused by BA.1, compared to those newly infected with BA.2 (aOR: 1.9 (1.5-2.6). This suggests immunity induced by BA.1 is less effective against a BA.4/5 infection than against a BA.2 infection.
RESUMO
Variants of concern (VOCs) of SARS-CoV-2 have caused resurging waves of infections worldwide. In the Netherlands, Alpha, Beta, Gamma and Delta variants circulated widely between September 2020 and August 2021. To understand how various control measures had impacted the spread of these VOCs, we analyzed 39,844 SARS-CoV-2 genomes collected under the Dutch national surveillance program. We found that all four VOCs were introduced before targeted flight restrictions were imposed on countries where the VOCs first emerged. Importantly, foreign introductions, predominantly from other European countries, continued during these restrictions. Our findings show that flight restrictions had limited effectiveness in deterring VOC introductions due to the strength of regional land travel importation risks. We also found that the Alpha and Delta variants largely circulated more populous regions with international connections after their respective introduction before asymmetric bidirectional transmissions occurred with the rest of the country and the variant dominated infections in the Netherlands. As countries consider scaling down SARS-CoV-2 surveillance efforts in the post-crisis phase of the pandemic, our results highlight that robust surveillance in regions of early spread is important for providing timely information for variant detection and outbreak control.
RESUMO
We reviewed the clinical performance of SARS-CoV-2 nucleic acid, viral antigen and antibody tests based on 94739 test results from 157 published studies and 20205 new test results from 12 EU/EEA Member States. Pooling the results and considering only results with 95% confidence interval width [≤]5%, we found 4 nucleic acid tests, among which 1 point of care test, and 3 antibody tests with a clinical sensitivity [≤]95% for at least one target population (hospitalised, mild or asymptomatic, or unknown). Analogously, 9 nucleic acid tests and 25 antibody tests, among which 12 point of care tests, had a clinical specificity of [≤]98%. Three antibody tests achieved both thresholds. Evidence for nucleic acid and antigen point of care tests remains scarce at present, and sensitivity varied substantially. Study heterogeneity was low for 8/14 (57.1%) sensitivity and 68/84 (81.0%) specificity results with confidence interval width [≤]5%, and lower for nucleic acid tests than antibody tests. Manufacturer reported clinical performance was significantly higher than independently assessed in 11/32 (34.4%) and 4/34 (11.8%) cases for sensitivity and specificity respectively, indicating a need for improvement in this area. Continuous monitoring of clinical performance within more clearly defined target populations is needed.
