Serum study finds no subclinical H7N9 in Chinese health workers
A serologic study of healthcare workers in China's Zhejiang province, the area that has had the most cases in the H7N9 flu outbreak, found no asymptomatic infections with the new virus, according to a letter from Chinese researchers in Clinical Infectious Diseases.
The group examined 126 serum samples from healthy healthcare workers who had blood drawn during routine physical exams from Apr 1 to May 1. They compared the findings with samples from people who didn't work in health settings who lived in the cities of Taizhou, Hangzhou, and Shaoxing who also had physical exams with bloodwork during the same period.
None of the health workers or controls had evidence of infection as measures by a H7 hemagglutination inhibition titer of 20 or more. The findings were similar to a recent study in poultry workers—another high-risk group—that showed no evidence of subclinical H7N9 infection.
Researchers suggested that H7N9 might not be able to cause asymptomatic or subclinical infections and that perhaps that factor prevents people from acquiring H7N9 immunity through such infections.
Jun 11 Clin Infect Dis letter
May 29 CIDRAP News Scan on previous study
US saw moderately severe flu season
In a snapshot of the flu season that just wrapped up, the US Centers for Disease Control and Prevention (CDC) said today that 2012-13 made its mark for several reasons, including a peak percentage of doctors' visits for flulike illness that, at 6.1%, was one of the highest since the current reporting system began in 1997.
Writing in Morbidity and Mortality Weekly Report (MMWR), the CDC said the rate of flu hospitalizations in older people was the highest since the agency started collecting that information in the 2005-06 season. The number of pediatric flu deaths topped all years since data collection began, except for the 2009 H1N1 months.
Flu activity, as measured by percentage of respiratory specimens testing positive, peaked early, by the week ending Dec 29. The H3N2 virus predominated until the end of February, when influenza B edged it out.
The CDC warned that although flu activity is typically low during the summer, cases and sporadic outbreaks continue to be detected. It urged clinicians to keep their guard up and consider novel influenza viruses, especially in sick patients who have had swine exposure and in those who get sick after traveling to China.
Jun 14 MMWR report