An international investigation with the collaboration of the Carlos III Health Institute (ISCIII) in Madrid (Spain) has demonstrated in a preclinical mouse model that flu vaccination, in addition to protecting against the virus, boosts the immune system's response to reduce mortality linked to secondary bacterial infections. The study, published in the Journal of Virology, was led by researchers from the Icahn School of Medicine at Mount Sinai in New York (USA), and included the participation from Spain of a team from the National Center for Microbiology (CNM) of the ISCIII and groups from the CEU San Pablo University in Madrid. Secondary bacterial infections, such as those caused by 'Streptococcus pneumoniae', are one of the main causes of serious complications and death during annual flu epidemics in at-risk populations - such as the elderly and immunocompromised patients. The results of this study open the door to new knowledge for human health, as they can help understand how flu-associated bacterial infections worsen the disease, and how vaccination can mitigate that risk, the ISCIII reported in a press release. The results of the research in mice indicate that a single dose of the 'inactivated trivalent vaccine' against the flu virus has allowed to reduce mortality in simultaneous viral and bacterial coinfections from 50 percent to 15; and in the case of so-called 'superinfections' - bacterial infections that appear only one week after the viral infection - this reduction in mortality has gone from 100 to 50 percent in the animals. The results can facilitate the understanding of why the flu opens the door to lethal bacterial infections, and suggest that vaccination can change this scenario and significantly improve survival, even with suboptimal vaccine doses. Although it is a study carried out in a mouse model, the authors have emphasized the importance of obtaining more data on how flu vaccination could reduce bacterial complications in humans, reinforcing its role as a key preventive tool.
