ABSTRACT
The presence of neutralizing antibodies (NAbs) against SARS-CoV-2 represent a surrogate marker of immunologic protection in populations at high risk of infection such as healthcare workers caring for hospitalized patients with COVID-19. As recommended by CDC and the European CDC, the use of rapid diagnostic tests during population-based evaluations offers an opportunity to identify individuals with serologic evidence of natural infection or who have undergone vaccination. We carried out a cross-sectional study to assess the presence of neutralizing antibodies against SARS-CoV-2 among medical providers at an intensive care unit of a large referral hospital in Alicante, Spain. In addition, we tested for the presence of neutralizing antibodies compared to serum of uninfected individuals from a Biobank. We were also interested in evaluating the use of a rapid lateral flow immunochromatography (LFIC) test against a surrogate ELISA viral neutralization test (sVNT). This rapid test demonstrated a specificity of 1.000 95% CI (0.91-1.00) and the sensitivity of 0.987 95% CI (0.93-1.00). The negative predictive value was 95%. After six months, this rapid test demonstrated that those immunized with two doses of BioNTech/Pfizer vaccine, maintained optimal levels of neutralizing antibodies. We concluded that all Health Care Workers develop NAbs and the use of this rapid immunochromatographic test represents a potential tool to be used in population-based studies to detect serological antibody responses to vaccination. Vaccination policies could benefit from this tool to assess additional doses of vaccine or boosters among high-risk populations.
ABSTRACT
The implementation of strategies to mitigate possible cases of COVID-19 were addressed at the University of Alicante for the safe reopening of the 2020/2021 academic year. To discover the prevalence of immunity against SARS-CoV-2, a study was designed using a rapid immunoassay test (carried out between 6 and 22 July 2020), and in addition a cross-sectional survey was conducted on risk factors, symptoms, predisposition for becoming vaccinated, and sources of information about COVID-19. A random sample, stratified by students, faculty, and administrative staff, was selected. The seroprevalence found was 2.64% (39/1479; 95% CI 1.8-3.4), and the adjusted seroprevalence was 2.89% (95% CI 2.1-3.7). The average age of the students was 23.2 years old, and 47.6 years old for staff. In relation to COVID-19, the following was found: 17.7% pauci-symptomatic, 1.3% symptomatic, 5.5% contact with cases, 4.9% confined, and 0.3% PCR positive. More than 90% complied with preventive measures. The proportion willing to receive the COVID-19 vaccine was 91%. Their sources of information were the Internet (74%) and television (70.1%). They requested that the university offer information (45.1%), training (27%), and provide Personal Protective Equipment (PPE) (26.3%). Lastly, 87.9% would repeat the test. A plan was established that included the follow-up of cases and contacts, random sample testing, training courses, bimodal teaching, a specific website, and the distribution of PPE.