Study finds no link between flu vaccination, venous thromboembolism
Flu vaccination in adults ages 50 and older doesn't appear to raise the risk of venous thromboembolism (VTE), according to a new study published in Vaccine that examined the connection between the two factors.
Flulike illness is associated with a higher risk of VTE, and the risk of VTE rises after age 50. Flu vaccination is known to trigger a temporary rise in inflammatory cytokines, hinting at a biologically plausible link between immunization and VTE, but not much is known about the risk.
To assess a possible link, a team of researchers from the Marshfield Clinic Research Institute, Kaiser Permanente, and the US Centers for Disease Control and Prevention (CDC) analyzed CDC Vaccine Safety Datalink records of people who experienced VTE during the months of September through December from 2007 through 2012. Of 1,488 possible cases, they reviewed the medical records of 508 patients, of which 492 were confirmed as having VTE.
The investigators found no increased risk in VTE in the 1 to 10 days following inactivated influenza vaccination compared with the control period (incident rate ratio [IRR] = 0.89, 95% confidence interval [CI], 0.69 to 1.17). However, in a post-hoc analysis, they found increased risk in current tobacco smokers (IRR = 2.56, 95% CI, 1.06 to 6.23).
The group concluded that the data are consistent with earlier findings and affirm the safety of yearly flu vaccination in the population, an important conclusion given that older people are known to be at higher risk for flu complications and are among the groups targeted for vaccination.
Sep 6 Vaccine abstract
H7N9 avian flu hospitalizes man from China's Hunan province
China reported one new H7N9 avian influenza infection this week, involving a 67-year-old man from Hunan province, Hong Kong's Centre for Health Protection (CHP) said in an update today.
The man, from the city of Zhangjiajie, became ill on Aug 27 and was hospitalized for severe pneumonia. Investigators found that he had been exposed to a live-poultry market before his symptom onset.
The newly reported illness raised the number of H7N9 cases in the fifth and biggest wave of activity to 757 cases. At least 281 of the infections were fatal. Though cases have slowed since a sudden rise last fall that lasted into spring, China continues to report sporadic cases in the summer months from a broad part of the country.
Sep 8 CHP update
H5N8 strikes more birds in Nigeria and South Africa
Nigeria and South Africa reported more highly pathogenic H5N8 avian flu outbreaks, according to separate notifications from the World Organization for Animal Health (OIE).
Nigeria's outbreak—its first involving H5N8 since early February—began on Aug 4 at a layer farm on Ogun state in the country's far southwest. The virus killed 150 of 100,000 birds, with the remaining ones slated for culling as part of the outbreak response. Investigators haven't determined the source of the outbreak, but they noted poor biosecurity measures at the farm.
In South Africa, H5N8 was detected again, this time at a commercial farm in North West province. The outbreak began on Sep 1, sickening 132 of 54,000 birds at the facility. The flock was slated for culling to curb the spread of the virus.
In another report, officials reported two other H5N8 outbreaks, affecting backyard swans and Chinese geese at a location in Western Cape province and white geese in Gauteng province. The outbreak start dates were Aug 26 and Aug 29, respectively. Between the two events, the virus killed 15 of 24 susceptible birds.
Sep 8 OIE report on H5N8 in Nigeria
Sep 8 OIE report on H5N8 in South African poultry
Sep 8 OIE report on H5N8 in other South African birds