There is a great demand for more rapid tests for SARS‐CoV‐2 detection to reduce waiting time, boost public health strategies for combating disease, decrease costs, and prevent overwhelming laboratory capacities. This study was conducted to assess the performance of 10 lateral flow device viral antigen immunoassays for the detection of SARS‐CoV‐2 in nasopharyngeal swab specimens. We analyzed 231 nasopharyngeal samples collected from October 2020 to December 2020, from suspected COVID‐19 cases and contacts of positive cases at Biotechnology Research Center laboratories, Tripoli, Libya. The performance of 10 COVID‐19 Antigen (Ag) rapid test devices for the detection of SARS‐CoV‐2 antigen was compared to a quantitative reverse transcription‐polymerase chain reaction (RT‐qPCR). In this study, 161 cases had symptoms consistent with COVID‐19. The mean duration from symptom onset was 6.6 ± 4.3 days. The median cycle threshold ( C t ) of positive samples was 25. Among the 108 positive samples detected by RT‐qPCR, the COVID‐19 antigen (Ag) tests detected 83 cases correctly. All rapid Ag test devices used in this study showed 100% specificity. While tests from six manufacturers had an overall sensitivity range from 75% to 100%, the remaining four tests had a sensitivity of 50%–71.43%. Sensitivity during the first 6 days of symptoms and in samples with high viral loads ( C t < 25), was 100% in all but two of the test platforms. False‐negative samples had a median C t of 34 and an average duration of onset of symptoms of 11.3 days (range = 5–20 days). Antigen test diagnosis has high sensitivity and specificity in early disease when patients present less than 7 days of symptom onset. Patients are encouraged to test as soon as they get COVID‐19‐related symptoms within 1 week and to seek medical advice within 24 h if they develop disturbed smell/taste. The use of rapid antigen tests is important for controlling the COVID‐19 pandemic and reducing the burden on molecular diagnostic laboratories.

Measurement of strength and durability of SARS-COV-2 antibody response is important to understand the waning dynamics of immune response to both vaccines and infection. The study aimed to evaluate the level of IgG antibodies against SARS-CoV-2 and their persistence in recovered, naïve, and vaccinated individuals. We investigated anti-spike RBD IgG antibody responses in 10,000 individuals, both following infection with SARS-CoV-2 and immunization with SARS-COV-2 AstraZeneca, Sputnik V, Sinopharm, and Sinovac. The mean levels of anti-spike IgG antibodies were higher in vaccinated participants with prior COVID-19 than in individuals without prior COVID-19. Overall, antibody titers in recovered vaccinee and naïve vaccinee persisted beyond 20 weeks. Vaccination with adenoviral–vector vaccines (AstraZeneca and Sputnik V) generates higher antibody titers than with killed virus vaccine (Sinopharm and Sinovac). Approximately two-thirds of asymptomatic unvaccinated individuals had developed virus-specific antibodies. A single dose of vaccine is likely to provide greater protection against SARS-CoV-2 infection in individuals with apparent prior SARS-CoV-2 infection, than in SARS-CoV-2-naive individuals. In addition, the high number of seropositivity among asymptomatic unvaccinated individuals showed that the number of infections are probably highly underestimated. Those vaccinated with inactivated vaccine may require more frequent boosters than those vaccinated with adenoviral vaccine. These findings are important for formulating public health vaccination strategies during COVID-19 pandemic.

Introduction The Delta variant has led to a surge in COVID-19 cases in Libya, making it crucial to investigate the impact of vaccination on mortality rates among hospitalized patients and the critically ill. This study aimed to explore the risk factors for COVID-19 mortality and the mortality rates among unvaccinated and vaccinated adults during the Delta wave who were admitted to a single COVID-19 care center in Tripoli, Libya. Methods The study involved two independent cohorts (n = 341). One cohort was collected retrospectively from May 2021-August 2021 and the second cohort was prospectively collected from August 2021-October 2021. Most of the patients in the study became ill during the Delta wave. The two cohorts were merged and analysed as one group. Results Most patients were male (60.5%) and 53.3% were >60 years old. The vast majority of patients did not have a previous COVID-19 infection (98.9%) and were unvaccinated (90.3%). Among vaccinated patients, 30 had received one dose of vaccine and only 3 had received two doses. Among patients who received one dose, 58.1% (18/31) died and 41.9% (13/31) survived. Most patients (72.2%) had a pre-existing medical condition. A multivariable prediction model showed that age >60 years was significantly associated with death (odds ratio = 2.328, CI 1.5–3.7, p-value = <0.0001). Conclusion Our results indicate that previous infection or full vaccination against COVID-19 significantly reduces hospitalization and death. However, a single vaccine dose may not be adequate, especially for older individuals and those with underlying medical conditions. High-risk older patients with comorbidities should be fully vaccinated and offered up to date bivalent COVID-19 booster doses.

Background: Natural and vaccine-induced immunity play an important role in controlling the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Understanding humoral immunity to SARS-CoV-2 is of great importance for evaluating vaccine performance and inform public health decisions. Objective: We aimed to evaluate the level of IgG antibodies against SARS-CoV-2 and their persistence post infection or post-vaccination. Methods: A serological analysis (Immunoassay) to investigate the level of anti-spike IgG antibody responses following infection with SARS-CoV-2 or immunization with the first or second dose of the AstraZeneca, Sputnik, Sinovac and Sinopharm vaccines was performed. Results: A total of 9460 seropositive individuals were recruited. The mean levels of anti-spike IgG antibodies were higher in vaccinated participants with prior COVID-19 infections than in individuals without prior infection. Decline for IgG antibodies were faster in vaccinated individuals without previous COVID-19 infection compared to those with previous COVID-19 infection. Conclusion: A single dose of the vaccine is likely to provide greater protection against SARS-CoV-2 infection in subjects with prior SARS-CoV-2 infection, than in SARS-CoV-2-naive individuals. In addition, previous COVID-19 infection elicited robust and sustained levels of SARS-CoV-2 antibodies in vaccinated individuals.