It is still a good time to get your flu shot.Speaking in Montauk on Monday at a business conference at Gurney’s Resort, Dr. Thomas McGinn, who oversees physician operations for the giant hospital network Northwell Health, said that influenza cases on Long Island were spiking and that the vaccine offers a needed degree of protection. Although it has been reported that this year’s flu shot is only partially effective, Dr. McGinn said some defense is better than none.