NEWS SCAN: Benefit of H1N1 vaccine, flu deaths in Asia, E coli treatment lessons, local dengue in Miami, HEV68 respiratory illness

Sep 29, 2011

CDC lowers estimate of vaccine benefits during H1N1 pandemic
In a notice to readers, the US Centers for Disease Control and Prevention (CDC) today lowered its estimate of the beneficial impact of pandemic 2009 H1N1 vaccine because of a computer modeling error. In a report on May 20, the agency had said that the vaccine and antiviral drugs prevented an estimated 5 million to 10 million cases, 30,000 hospitalizations, and 1,500 deaths over the course of the pandemic. However, today the CDC said, "As a result of a programming error, the model used to estimate the impact of vaccination did not adequately adjust for the decreasing risk for disease as the pandemic progressed, and thus the impact of vaccination was overestimated." The corrected estimates for the combined protective effect of vaccination and antiviral treatment are 713,000 to 1.5 million cases, 23,000 hospitalizations, and 620 to 1,160 deaths averted. The agency cautions, "It is important to note that the error does not involve nor pertain to the effectiveness of the 2009 H1N1 vaccine, nor to estimates of the burden of the 2009 H1N1 pandemic, which resulted in approximately 43 million to 89 million cases, 195,000 to 403,000 hospitalizations, and 8,900 to 18,300 deaths, including 910 to 1,880 deaths among children."
Sep 30 MMWR notice

In Asia, subtropical cities may be harder hit by flu than tropical cities
The death rate from seasonal influenza in a tropical Asian city was lower than in two subtropical Asian cities, according to a study in Vaccine. Researchers from China and Singapore applied a standardized modeling strategy to mortality and virology data from subtropical Guangzhou and Hong Kong and tropical Singapore and found respective flu-related excess death rates of 10.6, 13.4, and 8.3 per 100,000 population. The authors point out, however, that all three cities used different surveillance methods, such as Hong Kong's relying more heavily on inpatient data. "Nonetheless," they note, "we standardized the comparison procedure by using the age-specific excess mortality rate as measurement for influenza effects, which could at least partially exclude the bias introduced by different surveillance systems in these cities." Also, they say the differences between cities "could be partially explained by socioeconomic factors and age structure."
Sep 28 Vaccine abstract

Clinicians share EHEC-HUS treatment lessons
German clinicians who treated patients with hemolytic uremic syndrome (HUS) during Europe's sprout-related Escherichia coli O104:H4 outbreak recently shared several lessons they learned, according to an overview of a Sep 9 event in Berlin that appears in Eurosurveillance today. In one unusual finding, 14 HUS patients treated at Hamburg-Expender University who were assessed as having severe kidney damage based on histopathological images recovered better than expected, and none will need regular dialysis. The researcher, Dr Udo Helmchen, said initial histopathological ratings may have been misleading. The presentations did not help resolve unanswered questions about monoclonal antibody (Eculizumab) treatment for patients not responding to other treatments such as plasma exchange therapy or the use of antibiotics for enterohemorrhagic E coli (EHEC) infections, according to the report. However, other clinicians reiterated the benefits they found for the use of immunoabsorption for patients who went on to experience neurologic symptoms about 5 to 12 days after the onset of gastrointestinal symptoms.  So far the E coli O104:H4 strain doesn't appear to have become established as an endemic strain in Germany. A German EHEC-HUS registry has data from 589 patients; the overall mortality rate was 4.4%.
Sep 29 Eurosurveillance report

Second locally acquired dengue case confirmed in Miami area
A 44-year-old Miami-area man has developed the county's second locally acquired case of dengue fever this year, local public health officials announced yesterday. The man's diagnosis was confirmed by laboratory tests, and he has made a full recovery, according to a press release from the Miami–Dade County Health Department (MDCHD). The first case was confirmed in March on the other side of the county, according to a Miami Herald story today, and the first locally acquired case in more than 50 years in the county occurred in November 2010. Speaking of the latest case, Dr. Vincent Conte, MDCHD's deputy director of epidemiology and disease control said, "It means it's in our area, not an imported disease." The county has also experienced 12 to 14 cases of imported dengue this year. The 44-year-old man had also contracted the disease 25 years ago, according to the Herald, but recovered without long-term effects.
Sep 29 Miami Herald story

CDC raises awareness of HEV68 respiratory disease
Clinicians should consider human enterovirus 68 (HEV68) infections as a cause of unexplained respiratory illnesses, the CDC said today in an MMWR report that detailed case clusters that occurred in the United States, Asia, and Europe over the past 2 years. The report describes six clusters, three of which occurred in the United States (Georgia, Pennsylvania, and Arizona). HEV68 disproportionately occurred in children. In most cases, the disease was mild, but some severe cases required intensive care. Three deaths were reported, two from the Philippines and one from Japan. The CDC said it's unclear if HEV68 is an emerging pathogen or if the disease is being diagnosed more because of improved testing methods. Though enteroviruses cause a wide range of symptoms, HEV68 is exclusively linked to respiratory symptoms, with new-onset wheezing or asthma exacerbation as notable symptoms. The CDC warned clinicians that some diagnostic tests might not detect HEV68 or could misidentify it. The CDC said the cases in its report were confirmed with the gold standard test: partial sequencing of the structural protein genes, VP4-VP2 or VP1 capsid proteins.
Sep 29 MMWR report

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