Using survey data to estimate the impact of the omicron variant on vaccine efficacy against COVID-19 infection.

Symptoms-based detection of SARS-CoV-2 infection is not a substitute for precise diagnostic tests but can provide insight into the likely level of infection in a given population. This study uses symptoms data collected in the Global COVID-19 Trends and Impact Surveys (UMD Global CTIS), and data on variants sequencing from GISAID. This work, conducted in January of 2022 during the emergence of the Omicron variant (subvariant BA.1), aims to improve the quality of infection detection from the available symptoms and to use the resulting estimates of infection levels to assess the changes in vaccine efficacy during a change of dominant variant; from the Delta dominant to the Omicron dominant period. Our approach produced a new symptoms-based classifier, Random Forest, that was compared to a ground-truth subset of cases with known diagnostic test status. This classifier was compared with other competing classifiers and shown to exhibit an increased performance with respect to the ground-truth data. Using the Random Forest classifier, and knowing the vaccination status of the subjects, we then proceeded to analyse the evolution of vaccine efficacy towards infection during different periods, geographies and dominant variants. In South Africa, where the first significant wave of Omicron occurred, a significant reduction of vaccine efficacy is observed from August-September 2021 to December 2021. For instance, the efficacy drops from 0.81 to 0.30 for those vaccinated with 2 doses (of Pfizer/BioNTech), and from 0.51 to 0.09 for those vaccinated with one dose (of Pfizer/BioNTech or Johnson & Johnson). We also extended the study to other countries in which Omicron has been detected, comparing the situation in October 2021 (before Omicron) with that of December 2021. While the reduction measured is smaller than in South Africa, we still found, for instance, an average drop in vaccine efficacy from 0.53 to 0.45 among those vaccinated with two doses. Moreover, we found a significant negative (Pearson) correlation of around - 0.6 between the measured prevalence of Omicron in several countries and the vaccine efficacy in those same countries. This prediction, in January of 2022, of the decreased vaccine efficacy towards Omicron is in line with the subsequent increase of Omicron infections in the first half of 2022.

Estimating the COVID-19 Prevalence in Spain With Indirect Reporting via Open Surveys.

During the initial phases of the COVID-19 pandemic, accurate tracking has proven unfeasible. Initial estimation methods pointed toward case numbers that were much higher than officially reported. In the CoronaSurveys project, we have been addressing this issue using open online surveys with indirect reporting. We compare our estimates with the results of a serology study for Spain, obtaining high correlations (R squared 0.89). In our view, these results strongly support the idea of using open surveys with indirect reporting as a method to broadly sense the progress of a pandemic.

Telemedicine for adult congenital heart disease patients during the first wave of COVID-19 era: a single center experience.

AIM: To summarize our experience on the implementation of a telemedicine service dedicated to adult congenital heart disease (ACHD) patients during the lockdown for the first wave of Coronavirus disease 2019 (COVID-19). METHODS: This is a prospective study enrolling all ACHD patients who answered a questionnaire dedicated telematic cardiovascular examination. RESULTS: A total of 289 patients were enrolled, 133 (47%) were male, 25 (9%) were affected by a genetic syndrome. The median age was 38 (29-51) years, whereas the median time interval between the last visit and the telematic follow-up was 9.5 (7.5-11.5) months. Overall, 35 patients (12%) reported a worsening of fatigue in daily life activity, 17 (6%) experienced chest pain, 42 (15%) had presyncope and 2 (1%) syncope; in addition, 28 patients (10%) presented peripheral edema and 14 (5%) were orthopneic. A total of 116 (40%) patients reported palpitations and 12 had at least one episode of atrial fibrillation and underwent successful electrical (8) or pharmacological (4) cardioversion. One patient was admitted to the emergency department for uncontrolled arterial hypertension, five for chest pain, and one for heart failure. Two patients presented fever but both had negative COVID-19 nasal swab. CONCLUSION: During the COVID-19 pandemic, the use of telemedicine dramatically increased and here we report a positive experience in ACHD patients. The postpandemic role of telemedicine will depend on permanent regulatory solutions and this early study might encourage a more systematic telematic approach for ACHD patients.