Raising concern over the rising COVID-19 cases in Delhi, Lok Nayak Jai Prakash Narayan (LNJP) Hospital MD Dr Suresh Kumar on Saturday said it's necessary for all to take the booster dose of COVID-19 vaccine. "Positivity rate has gone up along with hospitalisation," he said. "People need to be alert, especially those...who are already suffering from serious diseases," Kumar added.