Study: High-dose flu vaccine benefits seniors, regardless of prior-year dose
A new analysis of data from a large randomized trial suggests that the high-dose (HD) flu vaccine is more protective in seniors than the standard-dose (SD) vaccine, and this benefit is not affected by which formulation seniors received in the previous flu season.
The study, reported Feb 21 in Clinical Infectious Diseases, was conducted by researchers from Sanofi Pasteur, Vanderbilt University, and the University of Pittsburgh. It was sponsored by Sanofi, which produces the high-dose vaccine, introduced in 2010.
The original study was a double-blind, randomized controlled trial that compared the efficacy of HD and SD vaccines in 14,500 seniors (65 years and older) over two flu seasons. More than half (7,643) of the year 1 participants re-enrolled in year 2; vaccines were randomly assigned both years. The authors note that recent observational studies suggest that previous flu vaccination may influence the effectiveness of current-season vaccination.
The researchers examined the incidence of lab-confirmed flu in year 2 among the various vaccine assignment groups. Compared with those who received SD in both years, those who received HD in year 2 had better protection. The relative vaccine efficacy (VE) for the year 2 HD recipients was 28.3% overall; it was 25.1% for those who received HD both years and 31.6% in those who had received SD in year 1. (The study did not include an unvaccinated group, so there was no measure of absolute VE.)
In addition, the researchers used multivariate regression models to determine that year 1 vaccination had no significant effect on year 2 VE (P = 0.43). The models affirmed that year 2 HD vaccination was significantly linked to lower flu risk (P = 0.043). Further, year 2 HD recipients had significantly higher flu antibodies (measured by hemagglutination inhibition) than those in the other vaccine groups.
The authors also report that they found no safety concerns associated with the HD vaccine.
Feb 21 Clin Infect Dis study
Hong Kong reports imported H7N9 case from China
Hong Kong's Centre for Health Protection (CHP) today announced an imported H7N9 avian influenza case from the mainland, its first in the fourth wave of illnesses in the region. The patient is a 60-year-old man from Jiangsu province who started having symptoms on Feb 8, 3 days after he arrived in Hong Kong.
He was initially admitted to a hospital on Feb 11, where he tested negative for influenza A and was diagnosed with pneumonia. The man was discharged on Feb 15 but sought care from a private clinic on Feb 18 and 22. Further tests on samples taken during his hospitalization were positive for H7N9, and he was admitted to a different hospital today and is listed in stable condition.
The man's son, who has a sore throat but no fever, has been admitted to the same hospital for observation, and his wife currently has no symptoms. The CHP said tracing is underway for the man's other Hong Kong contacts.
An investigation suggests the man may have been exposed to the virus during a visit to the wet market in his hometown of Suzhou.
The CHP said the man's illness is Hong Kong's 14th imported H7N9 case since the virus first emerged in 2013. The latest illness, plus a retrospective report of a healthcare worker from Guangdong province infected in 2015, lifts the global total to 742, according to a case list maintained by FluTrackers, an infectious disease news message board.
Feb 23 CHP statement
FluTrackers H7N9 case list
Indiana lifts H7N8 outbreak restrictions
Indiana's state veterinarian yesterday lifted the control zone in a Dubois County area hit by recent H7N8 avian influenza outbreaks, clearing the way for poultry producers to resume normal operations and movements of birds and poultry products.
The 6.2-mile control zone was established Jan 15 after highly pathogenic H7N8 was detected on a Dubois County turkey farm, according to a statement yesterday from the Indiana Board of Animal Health (IBAH). Testing in the wake of the finding turned up the low-pathogenic form of H7N8 virus at nine of the county's other turkey farms. Birds at all of the farms, plus those at a nearby egg farm thought to be at risk, were culled.
Yesterday's release of the control zone follows a 38-day testing period at farms in the control zone. Officials had also placed an additional 6.2-mile surveillance zone around the control zone, and yesterday’s action lifted that measure as well.
Bret Marsh, DVM, Indiana's state veterinarian, said in the statement, "We are pleased to be where we are today, just 38 days after HPAI was identified in Dubois County. This is an unprecedented event for the state of Indiana, and the level of cooperation and response at all levels has been incredible."
Feb 22 IBAH statement