THURSDAY, Oct. 8 (HealthDay News) -- There are early signs that the 2008/2009 trivalent inactivated seasonal flu vaccination offers some protection against influenza A/H1N1, particularly in its most severe forms, but this should not be taken to mean that vaccination against swine flu is superfluous, according to a study published online Oct. 6 in BMJ.
Lourdes Garcia-Garcia, M.D., of the Instituto Nacional de Salud Publica in Cuernavaca, Mexico, and colleagues conducted a study of 60 patients with confirmed A/H1N1 infection, and 180 controls matched for age and socioeconomic status who had diseases other than pneumonia or influenza-like illness. They looked at the rates of hospitalization, need for mechanical ventilation, and mortality in both groups of patients.
Patients in the control group were more likely than those in the case group to be at high risk of complications from influenza due to chronic conditions, and were more likely to have received vaccination against seasonal flu, which protected them to some extent against swine flu, the researchers found. The case cohort had higher rates of hospitalization, ventilation, and death. However, the authors caution that the study was retrospective and the sample size was small.
"The estimates for vaccine effectiveness could be inflated owing to a high prevalence of chronic conditions and vaccination in our control population," the authors write. "Notwithstanding this contribution to protection, a specific vaccine against A/H1N1 2009 is crucial."