Seguimos con la Influenza A H1 N1

Con el enfriamiento del hemisferio Norte esperamos un repunte de la epidemia de influenza A H1 N1, por lo que los siguientes datos publicados por el Colegio Americano de Médicos en el ACP Internist Weekly del 6 de Octubre del 2009, son muy útiles e interesantes. Además contien enlaces para profundizar sobre los temas que incluye.
Influenza: masks, bacteria and vaccination effectiveness
A comparison of surgical masks and N95 respirators, reports of bacterial co-infections, and evaluations of the effectiveness of widespread vaccination were among the top news about influenza last week.
Surgical masks were about as effective as N95 respirators in preventing influenza infection among health care workers in a recent randomized trial. More than 400 nurses in eight Ontario hospitals were assigned to wear either a fit-tested N95 respirator or a surgical mask when providing care to patients with febrile respiratory illness during the 2008-2009 influenza season. Influenza infection was measured by polymerase chain reaction or a fourfold rise in hemagglutinin titers. Influenza infection occurred in 50 nurses (23.6%) in the surgical mask group and 48 (22.9%) in the respirator group, an absolute risk difference of -0.73% (P=0.86). The results were published online Oct. 1 by the Journal of the American Medical Association.
The level of protection provided by the two kinds of masks appears to be similar in routine health care settings, although the results cannot be generalized to higher-risk procedures producing aerosolization, the study authors concluded. Current CDC recommendations call for N95 respirators for all health care worker contacts with influenza patients, although the agency is now reviewing its guidelines. According to an accompanying editorial, the JAMA study will likely not resolve debate on the issue, and should not distract from other means to prevent influenza spread in health care facilities, including hand hygiene, staying home from work when sick and vaccination of health care workers.
Vaccination against pneumococcus could play a role in reducing mortality from H1N1 influenza, according to the CDC's Morbidity and Mortality Weekly Report. An analysis of specimens from 77 patients who died of the pandemic strain this summer revealed that 22 of them (29%) had concurrent bacterial infections. Ten of the patients had pneumococcus. In addition to highlighting the benefits of vaccination, the findings underscore the importance of managing influenza patients who might also have bacterial pneumonia with both empiric antibacterial therapy and antiviral medications, the CDC said. The agency also released a 2009-2010 Influenza Season Triage Algorithm to assist physicians and those under their supervision in identifying indicators of and responses to symptoms of influenza-like illness in adults.
In the latest issue of Annals of Internal Medicine, researchers used mathematical models of New York City to forecast the effectiveness and cost-effectiveness of vaccination against the current H1N1 outbreak as well as a hypothetical pandemic of H5N1. In the case of an H5N1 pandemic, they concluded that expanded use of an adjuvanted vaccine would be worthwhile. As for the current influenza, the study concluded that vaccination would be effective in shortening the pandemic if about 40% of the population could be vaccinated in November, although the results would depend on when the epidemic peaks.