This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'ELISA is performed on a population with low prevalence. What would be the result of performing double screening ELISA tests - \nSelect and explain. \nA. Increased sensitivity and positive predictiv value, B. Increased sensitivity and negative predictive value, C. Increased specificity and positive predictive value, D. Increased specificity and negative predictive value', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The specificity of ELISA can be increased by carrying out ELISA in a row (series) using different HIV markers.\nWhen screening test is used in a series mode : -\n\n\n↑ Specificity\n↑ PPV\n↓ Sensitivity', 'role': 'assistant'}]