NEWS SCAN: Varicella vaccine benefits, polio vaccination gap, E coli hospital cases, H1N1 transmission

Apr 1, 2013

Varicella vaccine yields 9- to 10-fold decrease in childhood chickenpox
A large, long-term study of varicella vaccine effectiveness from Kaiser-Permanente Northern California, published today in Pediatrics, shows that the rate of chickenpox in children since licensure of the vaccine in 1995 has been decreased by a factor of 9 to 10. The researchers followed 7,585 children vaccinated in 1995 at 12 to 23 months of age for 14 years to determine the incidence of chickenpox and herpes zoster (shingles). They observed the impact of a second vaccine dose, introduced in 2006 and typically given at age 4 to 6 years, in 2,826 of the children as well. The vaccinated children had an average incidence of chickenpox of 15.9 per 1,000 person-years, a 9- to 10-fold decrease from the rate in the prevaccine era, and the vaccine's effectiveness held steady over the study period. "Breakthrough" cases (ie, in children who did receive vaccine) occurred in 1,505 children, most of them shortly after the first dose, when herd immunity would have been low. Only 28 of these cases (0.37% of the total population) were classified as severe, and no cases were reported after a second vaccine dose. In the prevaccine past, about 90% of young children experienced chickenpox by young adulthood, with most cases severe. Confirmed cases of herpes zoster occurred in 46 vaccinated children, a decrease of about 40% from the prevaccine era, the authors found.
Apr 1 Pediatrics study abstract
Apr 1 Kaiser-Permanente press release

Pakistan conflicts block polio vaccination for 240,000 kids
A World Health Organization (WHO) official said recently that security concerns in Pakistan's tribal regions have prevented 240,000 children from being immunized against polio since July 2012, according to a Mar 29 Associated Press (AP) story. Dr Nima Saeed Abid, acting WHO chief in Pakistan, said the five polio cases from Pakistan this year have been concentrated in a core polio-endemic area that includes Khyber Pakhtunkhwa province, the Federal Administered Tribal Regions, parts of Karachi, Quetta, and two districts in western Balochistan province. He noted that Pakistan reported 58 cases in 2012, down from 198 in 2011. Abid also told the AP that 15 polio workers have been killed since July 2012. The Taliban and some other militant groups oppose polio vaccination for various reasons, including suspicions that it is a front for Western spies.
In other polio developments, the US Centers for Disease Control and Prevention (CDC) recently issued an update on its polio eradication efforts, which increased after Dec 2, 2011, when Director Tom Frieden, MD, MPH, activated the CDC's Emergency Operations Center (EOC) to help global efforts. Since the CDC's scale-up, 430 workers have supported polio efforts at the EOC and in the field, according to a Mar 29 statement. Of that total, 134 employees have completed 344 field deployments to Angola, Chad, Ivory Coast, and other areas. Each day about 70 to 80 people are working on polio eradication in the CDC's EOC. Examples of the activities include reviewing countries' polio eradication gaps and training needs, publishing joint eradication progress reports with the WHO, and providing operational support to Nigeria for its polio eradication response plan, according to the CDC.
Mar 29 CDC polio eradication update

CDC says 7 patients were hospitalized in E coli O121 outbreak
Seven of 24 case-patients in an outbreak of Escherichia coli O121 infections linked to frozen snacks were hospitalized, the Centers for Disease Control and Prevention (CDC) said in a Mar 29 update on the 15-state outbreak. One patient suffered hemolytic uremic syndrome (HUS), a potentially fatal kidney complication, but there have been no deaths, the CDC said. The outbreak was announced last week by the US Department of Agriculture's Food Safety and Inspection Service. Last week Rich Products Corp., Buffalo, N.Y., recalled 196,000 pounds of frozen chicken quesadillas and other snacks in connection with the outbreak. The CDC notice said illness-onset dates ranged from Dec 30, 2012, to Mar 9, and 78% of patients were age 21 or younger. Among 21 patients with available information, seven were hospitalized, the CDC said. The agency said Farm Rich products "are one likely source" of the infections, as 8 of 14 patients who were interviewed reported eating them. In other comments, the CDC said the E coli O121 DNA fingerprint (pulsed-field gel electrophoresis pattern) seen in the outbreak is rare, having been seen fewer than 30 times before in PulseNet, the national storehouse of foodborne-pathogen DNA data.
Mar 29 CDC statement
Related Mar 29 CIDRAP News story

Seasonal, pH1N1 flu show similar transmission dynamics
Transmission of the 2009 H1N1 pandemic flu virus (pH1N1) was similar to transmission of seasonal flu viruses in relation to climate and time of year, according to an analysis of 2009-10 data from the World Health Organization (WHO), published Mar 30 in Influenza and Other Respiratory Viruses. Countries with temperate climates had higher peak activity, shorter durations of activity, and higher proportions of pH1N1 than tropical and subtropical countries. The authors, from the US Centers for Disease Control and Prevention (CDC) and the WHO, studied data collected from June 2009 through August 2010 in 80 countries, 47 of them temperate and 33 tropical or subtropical. The median proportion of pH1N1 cases identified during the peak week of activity was higher in temperate countries than in tropical and subtropical countries (12% vs 9%, P < 0.01). Peak activity occurred in the fall-winter period in 98% of temperate countries. Median duration of activity was longer in tropical and subtropical countries than in temperate countries (27 vs 20 weeks, P < 0.01). Countries' central latitude and the proportion of all flu specimens identified as pH1N1 showed a positive correlation (0.76; P < 0.01). The patterns are all similar to those occurring with seasonal influenza and may be useful for future pandemic planning, the authors say.
Mar 30 Influenza Other Respir Viruses abstract


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