Infectious Diseases Society of America, Oct. 29-Nov. 1, 2009Last Updated: November 03, 2009.
The Infectious Diseases Society of America 47th Annual Meeting took place Oct. 29 to Nov. 1 in Philadelphia and attracted nearly 5,000 attendees from more than 70 different countries.
"The hot theme is pandemic influenza. That has clearly taken the forefront," said program chair, Paul G. Auwaerter, M.D., of the Johns Hopkins School of Medicine in Baltimore. "The main themes on influenza are the epidemiology of the H1N1 epidemic, reinforcing that the vaccine produces good antibody responses and appears safe. We also have a lot of interesting data that suggests that immunization of pregnant women reduces the number of low birth-weight babies."
In one study, Saad B. Omer, Ph.D., of Emory University in Atlanta, and colleagues analyzed data on 6,410 births, and found that maternal flu shots were associated with a significantly decreased risk of premature delivery and low birth-weight (odds ratios, 0.36 and 0.30, respectively).
The study was supported in part by research grants from Wyeth and Sanofi.
In a second study, Marietta Vazquez, M.D., of the Yale University School of Medicine in New Haven, Conn., and colleagues found that the mother's flu shot given during pregnancy was 78.9 percent effective in preventing her non-vaccinated infant from being hospitalized during the first year of life, and 85.3 percent effective in preventing hospitalization from infancy to six months.
"These results will have a positive impact, not only on susceptible infants, but will prove to be cost-effective," Vazquez said during a teleconference. "If you think about this, we are talking about one vaccine protecting two individuals."
"Of course, these studies were done in the seasonal influenza era," Auwaerter said. "However, the important aspect is that pregnant women remain one of the lowest immunized groups. Only about 17 percent of pregnant women are immunized."
Other important H1N1 studies showed that the virus can spread from person to person, despite prior treatment with oseltamivir, and that virus shedding can continue for up to 13 days.
In one study, Natalie J. Dailey, M.D., of the North Carolina Division of Public Health Communicable Disease Branch in Raleigh, and colleagues reported on a 2009 outbreak among campers and staff at a summer camp in North Carolina, including two cases that developed among female campers who had initiated oseltamivir therapy, one of whom transmitted the virus to her cabin mate. Both cases were related to viral mutations that were apparently drug-resistant.
"It is likely that this resistant virus was passed from one camper to the other based on the timing between the illnesses and two genetic mutations found in the virus in both campers," Dailey said during a teleconference. "A small number of cases of oseltamivir-resistant virus have been seen in the United States so far, but these were the first cases reported in otherwise healthy individuals, and the first which appeared to have spread from one person to another. This suggests that using oseltamivir to prevent influenza in healthy people may increase the risk of resistance. If resistance became widespread, oseltamivir would no longer be effective."
Another team of researchers from the Pennsylvania Department of Health in Harrisburg evaluated H1N1 shedding duration after fever onset in 26 children. They found that the median duration of shedding was six days, but ranged up to a maximum of 13 days. The data suggested how long students should be kept at home before returning to school, the researchers concluded.
Other key research presented at the meeting suggested that statin users may develop less severe influenza infections. "That's a preliminary finding, so obviously it needs to be studied further," Auwaerter said. "There are a variety of plausible hypotheses why statins may modulate some of the immune responses to the virus."
Meredith Vandermeer, of the Oregon Public Health Division in Portland, and colleagues identified 3,921 influenza-associated hospitalizations, including 1,019 (26 percent) in which the patients received statins. They found that statin use was associated with a significantly decreased risk of death during hospitalization (adjusted odds ratio, 0.34).
Many abstracts addressed the issue of antibiotic resistance. Among them was a study on multi-drug resistant Acinetobacter baumanii conducted by researchers from the Henry Ford Hospital in Detroit. They found that risk factors associated with infection or colonization included longer length of hospital stay, admission from a long-term care facility, and prior antibiotic use.
"This is a pressing problem, especially in the hospital environment where we have a limited menu of antibiotics to use, because there are so few in development," Auwaerter said.
A co-author of the study reported financial relationships with various pharmaceutical companies.
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