On Wednesday, US researchers claimed that seniors who have been infected with or vaccinated against seasonal flu may have a type of immunity produced by cells that protects them from the swine flu virus.
They explained that the pandemic H1N1 virus has parts found in earlier flu strains, and some individuals over the age of 60, who may have been exposed to similar viruses in their youth, may have some latent immune cells that protect them.
"These findings indicate that human populations may have some level of existing immunity to the pandemic H1N1 influenza and may explain why the 2009 H1N1-related symptoms have been generally mild," said Carol Cardona of the University of California Davis School of Veterinary Medicine. Her study appears in the journal Emerging Infectious Diseases.
It seems that this immunity may be serving to weaken the effects of swine flu. "The meaning clinically is you are going to get sick but it may not be as severe if you had no immunity whatsoever," Cardona said in a telephone interview earlier to the media.
Cardona said much attention is given to antibodies that recognize and destroy foreign invaders.
The body also makes cells, known as cytotoxic T-cells, which secrete antiviral chemicals that kill infected cells and clear the virus from the body. It is these cells that may be offering protection.
