Serological Evidence of Zika Virus Infection in Febrile Patients and Healthy Blood Donors in Sabah, Malaysian Borneo, 2017–2018

Several Zika virus (ZIKV) seroprevalence studies have been conducted in Africa, Asia, Oceania, the Americas, and the Caribbean. However, studies on ZIKV seroprevalence are limited in Malaysia though several studies have shown that the disease is endemic in the Malaysian state of Sabah. To evaluate the seroprevalence of ZIKV infection, 818 serum samples were collected from febrile patients and healthy blood donors from the Kudat and Kota Kinabalu districts in Sabah from 2017 to 2018. They were screened for ZIKV infection by IgM and IgG ELISA, and positive ZIKV IgM samples were subjected to a 90% neutralization test for confirmation. Twenty-four (6% [95% CI 4 to 8]) confirmed and two (0.5% [95% CI 0.13 to 1.8]) probable ZIKV infections were detected among 400 febrile illness patients. Of 418 healthy blood donor samples, six (1.4% [95% CI 0.65 to 3]) were determined as confirmed ZIKV infections and six (1.4% [95% CI 0.65 to 3]) indicated probable ZIKV infection. This is the first study on the seroprevalence of ZIKV infections among patients and healthy blood donors in Sabah. Compared with previous studies in Malaysia, this study shows that the incidence of ZIKV infection has increased. It also suggests that a sero-surveillance system is essential to determine the circulation of ZIKV in Sabah, Malaysia.

Efficient Identification of High-Titer Anti-Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antibody Plasma Samples by Pooling Method

ABSTRACT Context.– The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has elicited a surge in demand for serological testing to identify previously infected individuals. In particular, antibody testing is crucial in identifying COVID-19 convalescent plasma (CCP), which has been approved by the Food and Drug Administration (FDA) under the Emergency Use Authorization (EUA) for use as passive immune therapy for hospitalized patients infected with COVID-19. Currently, high-titer CCP can be qualified by Ortho's Vitros COVID-19 IgG antibody test (VG). Objective.– To explore the use of an efficient testing method to identify high-titer CCP for use in treating COVID-19 infected patients and track COVID-19 positivity over time. Design.– We evaluated an ELISA-based method that detects antibodies specific to the SARSCoV-2 receptor binding domain (RBD) with individual and pooled plasma samples and compared its performance against VG. Using the pooled RBD-ELISA (P-RE) method, we also screened over 10,000 longitudinal healthy blood donor samples to assess seroprevalence. Results.– P-RE demonstrates 100% sensitivity in detecting FDA-defined high-titer samples when compared to VG. Overall sensitivity of P-RE when compared to VG and our individual sample RBD-ELISA (I-RE) were 83% and 56%, respectively. When screening 10,218 healthy blood donor samples by P-RE, we found the seroprevalence correlated with the local infection rates with a correlation coefficient of 0.21 (P< .001). Conclusions.– Pooling plasma samples can be used to efficiently screen large populations for individuals with high-titer anti-RBD antibodies, important for CCP identification.

Covid-19 Seroprevalence rate in healthy blood donors from a community under strict lockdown measures

BackgroundCovid-19 seroprevalence rates and serological tests are important tools in understanding the epidemiology of the disease and help in the fight against it. Seroprevalence rates vary according to the population studied and the test employed and they range from 0.133 to 25.7%. The purpose of this study is to assess the seroprevalence rate in a population of healthy blood donors living under strict lockdown measures in Jordan which has in total 71 confirmed cases per million population.MethodsLeft over sera and plasma samples from 746 healthy blood donors were tested using a commercially available FDA approved kit having a specificity of 100%. External positive controls were used for validation.ResultsMore than 80% of the donors were men 18–63 year old and residing in the capital city of Jordan, Amman. All tested specimens were negative yielding a zero seroprevalence rate in this healthy blood donor population.ConclusionStrict lockdown measures effectively limit intracommunity spread of the infection, however at the cost of lack of any acquired community immunity. Additionally the use of highly specific test is recommended in low prevalence setting.