Swine Flu cases this winter season are on a rise. The outbreak has led in 4,571 cases and 169 deaths across the country. 40% of the cases have emerged from Rajasthan followed by Gujarat and Delhi, according to Integrated Disease Surveillance Programme. Experts advise, the most vulnerable - young and elderly - should get vaccinated well ahead of the peak season (December-January) as the vaccination takes approximately three weeks to be effective. Dr Rahul Sharma, a Senior Consultant, Pulmonary Centre in Metro Hospitals, says this year there has been an increase in patient numbers since last year. "People are advised to consult a doctor as soon as severe flu symptoms persist. It is very important to be diagnosed timely and to take precautions against crowded places," he adds.