Impaired humoral immunity to BQ.1.1 in convalescent and vaccinated patients.

Determining SARS-CoV-2 immunity is critical to assess COVID-19 risk and the need for prevention and mitigation strategies. We measured SARS-CoV-2 Spike/Nucleocapsid seroprevalence and serum neutralizing activity against Wu01, BA.4/5 and BQ.1.1 in a convenience sample of 1,411 patients receiving medical treatment in the emergency departments of five university hospitals in North Rhine-Westphalia, Germany, in August/September 2022. 62% reported underlying medical conditions and 67.7% were vaccinated according to German COVID-19 vaccination recommendations (13.9% fully vaccinated, 54.3% one booster, 23.4% two boosters). We detected Spike-IgG in 95.6%, Nucleocapsid-IgG in 24.0%, and neutralization against Wu01, BA.4/5 and BQ.1.1 in 94.4%, 85.0%, and 73.8% of participants, respectively. Neutralization against BA.4/5 and BQ.1.1 was 5.6- and 23.4-fold lower compared to Wu01. Accuracy of S-IgG detection for determination of neutralizing activity against BQ.1.1 was reduced substantially. We explored previous vaccinations and infections as correlates of BQ.1.1 neutralization using multivariable and Bayesian network analyses. Given a rather moderate adherence to COVID-19 vaccination recommendations, this analysis highlights the need to improve vaccine-uptake to reduce the COVID-19 risk of immune evasive variants. The study was registered as clinical trial (DRKS00029414).

SARS-CoV-2 rapid antigen test: Fast-safe or dangerous? An analysis in the emergency department of an university hospital.

The use of Antigen point of care tests (AgPOCT) might be an essential tool to fight the coronavirus disease 2019 (COVID-19) pandemic. Manufacturer information indicates a specificity of about 95% and there is a growing interest to use these tests area-wide. Therefore, it is necessary to clarify whether AgPOCT can be used safely for "rule-in" (detection of positive patients) and for "rule-out" (valid negative testing). Two thousand three hundred and seventy-five patients received polymerase chain reaction (PCR) testing and AgPOCT for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) regardless of symptoms. The positive predictive value of symptomatic and asymptomatic patients was compared with a cut-off threshold cycle (C t ) value of ≤30 and in total. Five hundrded and fifty-one patients tested positive for the SARS-CoV-2 virus by PCR, of whom 35.2% presented without symptoms. In all patients, regardless of their symptoms or C t values, a sensitivity of 68.9% and a specificity of 99.6% were calculated for AgPOCT. In patients with C t values ≤30, a sensitivity of 80.5% (95% confidence interval: ±1.62) and a specificity of 99.6% were shown for all tests (symptomatic/asymptomatic). Highly infectious patients (C t ≤ 20), regardless of symptoms, were reliably detected by the AgPOCT. In infectious patients with C t values ≤30, the test has a sensitivity of about 80% regardless of COVID-19 typical symptoms, which is apparently less than the 96.52% specificity indicated by the manufacturer. Relevant improvement in test sensitivity by querying the patients who are symptomatic and asymptomatic is also not feasible. We strongly suggest that we critically question the use of AgPOCT for "rule-out," as they only provide a supposed safety.