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Source: http://www.cidrap.umn.edu/news-persp...an-nov-26-2013
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Flu Scan for Nov 26, 2013
Vaccine effectiveness in pregnancy; Flu mutation predictability; Social media and flu contest
Filed Under:
Influenza Vaccines; Influenza, General
Study finds vaccine protects about half of pregnant women from flu
Flu vaccine effectiveness (VE) varied from 44% to 53% over the 2010-11 and 2011-12 seasons among pregnant women, and getting a flu shot the previous year appeared to be just as effective as getting the current year's vaccine, according to a study in Clinical Infectious Diseases today.
Researchers from the Centers for Disease Control and Prevention's (CDC's) Pregnancy and Influenza Project Workgroup conducted a case-control study among Kaiser Permanente patients in two metropolitan areas in California and Oregon. They compared the vaccination rate in 100 lab-confirmed influenza case-patients with that of 192 controls who had acute respiratory illness (ARI) who tested negative for flu and 200 controls who did not have ARI and tested negative.
The team found an adjusted VE for the current-season vaccine against influenza A and B of 44% (95% confidence interval [CI], 5%-67%) using the influenza-negative controls for comparison and 53% (95% CI, 24%-72%) using the ARI-negative controls.
They also noted: "Receipt of the prior season's vaccine, however, had an effect similar to receipt of the current season's vaccine. As such, vaccination in either or both seasons had statistically similar adjusted VE using influenza-negative controls (VE point estimates range = 51%-76%) and ARI-negative controls (48%-76%)."
Nov 26 Clin Infect Dis abstract
H3N2 gene study finds flu mutations more predictable than thought
A study of seasonal H3N2 viruses that circulated from 1968 to 2003 found that mutations were more predictable than previously thought. An international team from the Netherlands, the United Kingdom, Australia, Russia, and the United States reported their findings in the Nov 22 issue of Science.
The team looked at genetic sequences of representative H3N2 viruses from 11 antigenic clusters that emerged during the 35-year period, a time that followed the introduction of the strain in humans. Their goal was to pinpoint the substitutions that drove the antigenic changes.
They found that at least 9 of 10 cluster transitions were mainly caused by single amino acid substitutions, and all of the substitutions occurred as seven positions close to the receptor binding site on the hemagglutinin. Five of the seven key positions occurred twice.
When they infected ferrets with viruses that contained the single amino acid changes they found differences in virus-specific antibody response. The researchers also found that similar positions drove recent antigenic changes in seasonal H1N1 and influenza B viruses.
The findings suggest that nature has selected for substitutions at only 7 of 131 positions that can cause antigenic changes, the team wrote. "This is an important change in our understanding of the antigenic evolution of seasonal influenza viruses."
The team also noted that the location of the key positions near the receptor-binding sites provides a clue that antibodies specific to that area play a key role in neutralizing the H3N2 virus.
Researchers noted that it's surprising that antigenic clusters appear relatively slowly, roughly every 3.3 years, given the high mutation rate of flu viruses and the observation that single amino acid substitutions can lead to new antigenic clusters. They suggested that the antigenic changes could come with a fitness cost that slows virus evolution.
Nov 22 Science abstract
CDC contest seeks flu season predictions from use of social media
The CDC has launched a competition aimed at modeling and predicting influenza activity, according to a news release from the agency yesterday.
Called "Predict the Influenza Season Challenge," the contest will award $75,000 to the entrant who is able to most successfully predict the timing, peak, and intensity of the current flu season nationally and at each or any Health and Human Services region level through mathematical and statistical models that use digital (social media) surveillance data, say details of the contest published in the Federal Register.
The competition is part of a national system of contests used by more than 50 government agencies that seeks to spur innovative solutions to national problems at a fraction of the cost of traditional means of funding.
Nov 25 CDC news release
Nov 25 Federal Register item giving details of the contest
Source:
Flu Scan for Nov 26, 2013
Vaccine effectiveness in pregnancy; Flu mutation predictability; Social media and flu contest
Filed Under:
Influenza Vaccines; Influenza, General
Study finds vaccine protects about half of pregnant women from flu
Flu vaccine effectiveness (VE) varied from 44% to 53% over the 2010-11 and 2011-12 seasons among pregnant women, and getting a flu shot the previous year appeared to be just as effective as getting the current year's vaccine, according to a study in Clinical Infectious Diseases today.
Researchers from the Centers for Disease Control and Prevention's (CDC's) Pregnancy and Influenza Project Workgroup conducted a case-control study among Kaiser Permanente patients in two metropolitan areas in California and Oregon. They compared the vaccination rate in 100 lab-confirmed influenza case-patients with that of 192 controls who had acute respiratory illness (ARI) who tested negative for flu and 200 controls who did not have ARI and tested negative.
The team found an adjusted VE for the current-season vaccine against influenza A and B of 44% (95% confidence interval [CI], 5%-67%) using the influenza-negative controls for comparison and 53% (95% CI, 24%-72%) using the ARI-negative controls.
They also noted: "Receipt of the prior season's vaccine, however, had an effect similar to receipt of the current season's vaccine. As such, vaccination in either or both seasons had statistically similar adjusted VE using influenza-negative controls (VE point estimates range = 51%-76%) and ARI-negative controls (48%-76%)."
Nov 26 Clin Infect Dis abstract
H3N2 gene study finds flu mutations more predictable than thought
A study of seasonal H3N2 viruses that circulated from 1968 to 2003 found that mutations were more predictable than previously thought. An international team from the Netherlands, the United Kingdom, Australia, Russia, and the United States reported their findings in the Nov 22 issue of Science.
The team looked at genetic sequences of representative H3N2 viruses from 11 antigenic clusters that emerged during the 35-year period, a time that followed the introduction of the strain in humans. Their goal was to pinpoint the substitutions that drove the antigenic changes.
They found that at least 9 of 10 cluster transitions were mainly caused by single amino acid substitutions, and all of the substitutions occurred as seven positions close to the receptor binding site on the hemagglutinin. Five of the seven key positions occurred twice.
When they infected ferrets with viruses that contained the single amino acid changes they found differences in virus-specific antibody response. The researchers also found that similar positions drove recent antigenic changes in seasonal H1N1 and influenza B viruses.
The findings suggest that nature has selected for substitutions at only 7 of 131 positions that can cause antigenic changes, the team wrote. "This is an important change in our understanding of the antigenic evolution of seasonal influenza viruses."
The team also noted that the location of the key positions near the receptor-binding sites provides a clue that antibodies specific to that area play a key role in neutralizing the H3N2 virus.
Researchers noted that it's surprising that antigenic clusters appear relatively slowly, roughly every 3.3 years, given the high mutation rate of flu viruses and the observation that single amino acid substitutions can lead to new antigenic clusters. They suggested that the antigenic changes could come with a fitness cost that slows virus evolution.
Nov 22 Science abstract
CDC contest seeks flu season predictions from use of social media
The CDC has launched a competition aimed at modeling and predicting influenza activity, according to a news release from the agency yesterday.
Called "Predict the Influenza Season Challenge," the contest will award $75,000 to the entrant who is able to most successfully predict the timing, peak, and intensity of the current flu season nationally and at each or any Health and Human Services region level through mathematical and statistical models that use digital (social media) surveillance data, say details of the contest published in the Federal Register.
The competition is part of a national system of contests used by more than 50 government agencies that seeks to spur innovative solutions to national problems at a fraction of the cost of traditional means of funding.
Nov 25 CDC news release
Nov 25 Federal Register item giving details of the contest