Study: Flu vaccine effectiveness may drop within a few months
The effectiveness of the influenza vaccine dropped from 52% at 3.5 months after vaccination to 22% more than 4 months after vaccination during the 2011-12 season, according to a study out of Spain today in BMC Infectious Diseases whose power was limited by a small sample size.
Researchers analyzed data from 342 primary care patients across the country who had influenza-like illness and for whom vaccination status and timing were known. Of these, 226 had lab-confirmed flu and 116 served as test-negative controls.
They found that, at 3.5 months after vaccination with trivalent inactivated vaccine (the flu shot), vaccine effectiveness (VE) against H3N2 flu—by far the most prevalent circulating strain—was 52% (95% confidence interval [CI], -3 to 78). VE fell to 40% (95% CI, -40 to 74) from 3.5 to 4 months after vaccination and to 22% (95% CI, -135 to 74) for longer than 4 months after vaccination.
The waning immunity appeared to be entirely tied to immune response in elderly patients. The researchers found the adjusted VE dropped from 85% (95% CI, 18 to 97) for patients older than 65 who were vaccinated 3 months before symptom onset to a null estimate for those in that age-group who were vaccinated more than 4 months before symptom onset. The trend, however, was not statistically significant.
The team did not find decreased VE with time in patients younger than 65 years.
The investigators determined that overall VE was 47% (95% CI, 7 to 70) against any type of influenza and 45% (95% CI, 0 to 69) against H3N2.
The authors conclude, "These results must be interpreted with caution because the study was limited by its small sample size. Therefore, although point estimates showed a substantial decrease with time since vaccination in the early phase, we could not demonstrate a significant decreasing influenza VE trend over time.
"The data support an urgent need for the development of new influenza vaccines providing better and longer-lasting protection."
Sep 23 BMC Infect Dis abstract
Community-associated kids' MRSA up about 10% per year
A multistate study of methicillin-resistant Staphylococcus aureus (MRSA) cases in kids found that healthcare-associated and hospital-onset MRSA stayed level from 2005 through 2010 but community-associated MRSA (CA-MRSA) rose about 10% each year.
The study, published today in Pediatrics, also found that invasive MRSA disproportionately affects newborns and Africa-American children.
Health officials from the Centers for Disease Control and Prevention and a number of states reported 876 total pediatric MRSA cases over the study period, 39% of which were in infants. CA-MRSA rose from 1.1 to 1.7 infections per 100,000 children from 2005 to 2010, for a yearly increase of 10.2% (95% CI, 2.7 to 18.2)
The scientists also found that the incidence of invasive MRSA in 2010 was higher among infants 90 days old or younger compared with their older counterparts (43.9 vs 2.0 per 100,000) and among African-American children compared with other races (6.7 vs 1.6 per 100,000).
Sep 23 Pediatrics abstract
Coalition asks for halt to pilot poultry inspection program
A consumers' coalition said last week that the US Department of Agriculture (USDA) should withdraw its proposal to modify poultry inspections as well as equivalency determinations of foreign inspection programs that rely on the USDA's hog pilot programs and to re-evaluate inspections in those countries.
In a Sep 20 letter to USDA Secretary Tom Vilsack, the Safe Food Coalition said it is concerned that a pilot poultry inspection proposal called HACCP-based Inspection Model Project (HIMP) "will have serious repercussions for food safety." The letter cited concerns raised by the US Government Accountability Office (GAO) earlier this month and the USDA's Office of the Inspector General in May, among other sources.
The Safe Food Coalition said that problems with the hog inspection program include a lack of comparable data, an inability to generalize from the pilot program, and a lack of information to determine whether the program is meeting its goals.
In response to the letter, a spokeswoman for the USDA's Food Safety and Inspection Service (FSIS), which oversees the pilot programs, said the HIMP poultry inspection program "is about making food safer," according to a Food Safety News (FSN) story today.
Also, in a Sep 4 FSN editorial FSIS Administrator Alfred Almanza defended HIMP, saying fecal material appears about half as often in HIMP poultry plants as non-HIMP plants and that Salmonella detections are 20% lower in HIMP plants. He also said that the GAO report lists only two recommendations, both of which FSIS is working to address.
The Safe Food Coalition comprises eight organizations, including the Center for Foodborne Illness Research and Prevention, the Center for Science in the Public Interest, the Consumer Federation of America, and Consumers Union.
Sep 20 Safe Food Coalition letter
Sep 23 FSN article
Sep 4 FSN editorial
