Flu Scan for May 08, 2017

H7N9 cases in China
;
UK H5N8 outbreak
;
'Herd' flu vaccine protection
;
2009 H1N1 containment

H7N9 activity expands in China

Over the weekend, Hong Kong's Centre for Health Protection (CHP) fleshed out more details on 22 recent H7N9 avian flu cases, 8 of them fatal, that were reported Apr 28 to May 4 from China's mainland, signaling continued steady activity in the country's fifth and biggest wave of infections.

The latest illness onsets range from Apr 14 to Apr 29, a sign that the outbreak is ongoing. Fourteen patients were men and 8 were women. Seventeen of the patients had a history of exposure to poultry, poultry markets, or mobile stalls.

One of the unique aspects of the fifth wave has been a much wider geographic spread outside of the typically affected southern and southeastern provinces, and the latest CHP update notes cases in nine provinces, plus the cities of Beijing and Chongqing.

Seven cases are from Hebei province in northern China, a region that had reported only a few previous illnesses. Six are from Sichuan, which has reported several recent infections.

In a related development, Shaanxi province in the northwest, which recently reported its first case, now has four cases, with the announcement of a new case from the city of Xi'an, according to a local government statement translated and posted today by Avian Flu Diary (AFD), an infectious disease news blog.

China has now reported at least 680 cases, with at least 196 of them fatal.
May 6 CHP update
May 8 AFD post

 

H5N8 avian flu strikes English backyard birds again

The United Kingdom's Department for Environment, Food and Rural Affairs (DEFRA) announced on May 6 that a second highly pathogenic H5N8 avian flu outbreak has been detected near the city of Thornton in Lancashire County in northwestern England.

News of the latest detection came just 2 days after an initial outbreak was reported in backyard birds at a holding near Thornton. The latest outbreak also involves a backyard flock, which contains nine chickens and ducks. A notification today from the World Organization for Animal Health (OIE) said the outbreak began on May 5, killing two of the birds. Authorities said the birds will be culled and an investigation is under way to find the source of the virus.

Officials placed a 3-kilometer (km) protection zone and 10-km surveillance zone around the property.
May 6 DEFRA update
May 8 OIE report

 

Meta-analysis shows flu vaccine 'herd' benefits in some settings

Vaccinating children against influenza may provide indirect protection for unvaccinated people in some settings, according to a new meta-analysis in Clinical Infectious Diseases.

Australian investigators included 30 studies in their review, including 9 randomized, controlled trials (RCTs), which are considered the "gold standard." Fourteen studies involved the live-attenuated (nasal spray) vaccine, 11 involved the flu shot, and 5 included both.

Of the 30 studies, 20 reported indirect protection effectiveness (IPE) against influenza or influenza-like illness (ILI) ranging from 4% to 66% in unvaccinated people. Of the 6 RCTs with full randomization, 1 study of immunized school-aged children showed IPE of 60% against lab-confirmed flu in the community and 3 household studies involving preschool vaccination showed an aggregate 22% IPE against acute respiratory infections or ILI.

Significant herd protection was also reported in a large-scale RCT that was not fully randomized, and three ecological studies of moderate quality in Japan that involved school-based programs and flu-related mortality in the elderly also showed some IPE.

The authors wrote, however, "Data on IPE in other settings are heterogeneous and lacked power to draw a firm conclusion."

They add, "Robust, large-scaled studies are required to quantify better the indirect protection from vaccinating children for different settings/endpoints."
May 5 Clin Infect Dis review

 

Study: 2009 H1N1 interventions had impact in camp setting

A large-scale intervention including antiviral prophylaxis helped reduce the impact of a 2009 H1N1 outbreak at a large physical training camp for college freshmen in Beijing in the fall of 2009, Chinese researchers reported May 5 in the International Journal of Infectious Diseases.

China reported its first 2009 H1N1 case in May of 2009, and when the new school began in late August and early September, researchers decided to test how well a combination of measures worked at controlling the spread of the disease at the training camp in a Beijing suburb. In China, college freshmen are required to perform a 2- or 4-week training period either at their school or at a camp.

The countermeasures against 2009 H1N1 included oseltamivir (Tamiflu) treatment for confirmed and possible cases and oseltamivir prophylaxis for all other training participants. The camp staff also isolated patients and possible case-patients and encouraged personal protection, hygiene and social distancing.

In the first 5 days of training, before the countermeasures began, the camp recorded 26 confirmed cases and 405 possible infections. After the intervention began, another 162 possible cases were reported, for a clinical attack rate of 18.2%, which was lower than the 80% that they had predicted in the absence of the interventions for a closed setting.

The researchers also noted that the attack rate they observed was similar to 11.4% seen in an earlier reported Singapore military setting where post-exposure oseltamivir ring prophylaxis was given. The authors said the findings provide additional support for the effectiveness of rapid containment of flu in settings such as schools and hospitals.
May 5 Int J Infect Dis abstract

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