Rhiza Labs FluTracker Forum

Commentary

http://www.recombinomics.com/News/04131 ... ution.html

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Emergence of 'new gene constellation' for influenza A (H3N2)
CDC reports 12 cases of human infection with influenza A (H3N2) variant viruses involving genes from avian, swine, and human viruses that had acquired the M gene from the influenza A (H1N1)pdm09 virus.

CDC reported the emergence of a "new gene constellation" for influenza A (H3N2) and its temporal association with 12 human infections of A (H3N2)v, leading the agency to state that a better understanding is needed of the ability of these viruses to cause human infection and the degree to which current seasonal influenza vaccines might generate cross-reactive antibodies to them.

In the April 12 Morbidity and Mortality Weekly Report (MMWR), CDC reported that since August 2011, it had gained knowledge of 12 cases of human infection with influenza A (H3N2) variant viruses involving genes from avian, swine, and human viruses (i.e., A [H3N2]v) that had acquired the M gene from the influenza A (H1N1)pdm09 virus. Of the cases, 11 were among children younger than 10 years of age and, for 6, the affected patients were not reported to have had recent exposure to swine, indicating that human transmission had occurred.

CDC analyzed presence of serum cross-reactive antibody in various age groups that were or were not vaccinated with the 2010–11 seasonal trivalent influenza vaccine (TIV). According to patient age, the following results were reported by the agency:

<10 years: Little or no cross-reactive antibody to A (H3N2)v
<3 years: No effect on cross-reactive antibody levels
≥10 years: Cross-reactive antibody detected in 20% to 30%
Adults: Modest increase in level of cross-reactive A (H3N2)v antibodies
Hemagglutination inhibition (HI) and microneutralization (MN) assays were performed. HI assays detect antibodies that slow the binding of virus to receptors on red blood cells, while MN assays quantify antibodies that neutralize and prevent infection, explained CDC. Serum HI titers of 40 or greater are related to lowered risk for influenza infection among adults. The 50% protective titer for the MN assay is not known; however, research regarding antibody response in patients infected with influenza A (H1N1)pdm09 virus showed that the MN titer was generally twofold higher than the HI titer when the HI titer was 160 or lower. Following this rationale, CDC presented titer achievements of 80 or more for the MN assay.

The agency stated that no evidence of antibodies to A (H3N2)v was found among 20 children aged 6 to 35 months, either before or after receiving the 2010–11 TIV. However, 40% or 45% of children demonstrated seroconversion (i.e., increase in antibody titer of a fourfold or more) to the seasonal A (H3N2) virus contained in the vaccine according to HI and MN assays.

This was in contrast to the results for 30 patients aged 18 to 49 years, in whom somewhat higher levels of prevaccination antibody to A (H3N2)v were observed. Among this age group, 33% attained HI titers of 40 or more and 43% MN titers of 80 or more. Following immunization with TIV, the percentage of patients aged 18 to 49 years with cross-reactive HI and MN antibody to A (H3N2)v increased to 50% and 63%, respectively. Consistent with CDC expectations, following vaccination, 80% of adults in this age group achieved HI titers of 40 or higher and 70% achieved MN titers of 80 or higher to the seasonal A (H3N2) vaccine component.

Prevaccination antibody to A (H3N2)v also was seen among older adults (aged ≥65 years), with 17% of 30 patients achieving HI titers of 40 or more and 30% achieving MN titers of 80 ore more. According to either assay, this increased to 40% postvaccination. As a comparison, for the seasonal A (H3N2) vaccine component, CDC reported that 67% and 90% of patients 65 years or older exhibited postvaccination HI titers of 40 or greater or MN titers of 80 or greater, respectively.

The results for these two adult populations, said CDC, indicated that "receipt of TIV boosted the levels of antibodies to A (H3N2)v, but to a lesser extent than the antibody response to the A (H3N2) vaccine component."

The agency further reported that a vaccine virus specific for A (H3N2)v has been developed and, if needed, could be used to produce an H3N2v vaccine. CDC advised that receiving the seasonal influenza vaccine continues to be the best option for protecting against circulating human influenza viruses for all age groups and that the vaccine could provide some protection against A (H3N2)v infection in the adult population.

Serum samples from a 2010–11 TIV study and the 2007–08 National Health and Nutrition Examination Survey (NHANES) were used for analysis. The TIV study included samples from patients aged 6–35 months, 18–49 years, and 65 years or older, and all serum samples were collected in fall 2010 before vaccination and at 3 to 4 weeks postvaccination. CDC noted that samples from children 4 to 17 years of age came from NHANES and were part of a larger set of samples received by the agency that were labeled with age and date of sample collection only.

Posted by Joe Sheffer (jsheffer@aphanet.org)
April 13, 2012
http://www.pharmacist.com/AM/Template.c ... ntID=28288

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Novel Influenza A Viruses:
One human infection with a novel influenza A virus was detected in a child in Utah. The child was infected with an influenza A (H3N2) variant virus similar to those identified in the 12 human infections that occurred between July and November 2011 in Indiana (2), Pennsylvania (3), Maine (2), Iowa (3) and West Virginia (2). The child has recovered. Contact with swine in the week preceding onset of the child’s illness was reported. State public health and agriculture officials are investigating case contacts and sources of exposure; no additional confirmed cases have been detected at this time. Additional information on these cases can be found in the CDC Flu Spotlight posting.

CDC is required to report all cases of human infection with novel (non-human) influenza viruses – including influenza viruses of swine origin – to the World Health Organization (WHO) as part of the International Health Regulations (IHR). Domestically, CDC reports these cases in this report and on its website. Early identification and investigation of human infections with novel influenza A viruses is critical in order to evaluate the extent of the outbreak and possible human-to-human transmission. Additional information on influenza in pigs and variant influenza infection in humans can be found at Information on Variant Influenza Viruses.

http://www.cdc.gov/flu/weekly/

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A 13th human case of infection with the influenza A(H3N2)v virus has recently been reported in the United States of America. This is the first variant A(H3N2) virus to be detected in 2012 and is similar to the previous ones which have 7 genes from the triple reassortant A(H3N2) viruses known to have been circulating in pigs in the North America and the M gene from the A(H1N1)pdm09 virus.

http://www.who.int/influenza/gisrs_labo ... index.html

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Commentary

http://www.recombinomics.com/News/04131 ... e_NOT.html

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The CDC's flu report included the variant H3N2 (H3N2v) infection in a child reported by Utah officials earlier this week. The CDC released additional details about the case yesterday, and the Canadian Press (CP) reported that the child is a girl who had toured a swine production facility.

The girl's illness is the first H3N2v infection to be reported this year and the 13th case since 2011 involving the same virus, a triple-recombinant swine-origin strain that contains the M gene of the 2009 H1N1 virus.

http://www.cidrap.umn.edu/cidrap/conten ... 12flu.html

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After some recent cases of swine flu emerging in people in the US, there are a lot of eyebrows that have been raised, indicating that it could be another comeback of the deadly virus. Health officials have reported that that a new human infection has surfaced along with the swine-origin H3N2 virus which is officially known as H3N2v virus.

Recently, there has been a case of a little girl in Utah which became the 13th person to have been affected with this new virus. It was last spotted in July, and since then, it has been playing hide-and-seek with the health officials, with a case surfacing after some while. What is more peculiar is that 12 cases out of the total 13 that have been reported are of children under the age of 18 years.

After being suffering from fever for some time, she was taken to a medical center, where she was tested positive for influenza. She was then given a flu shot of Tamilflu, after which, she recovered. Her family members and close contacts were also tested to make sure that none of them had caught the deadly virus, but all of them tested negative. It is being speculated that the girl had visited a swine processing plant a week before where she could have got the virus. This is the first case that has come up in Utah. Previously, cases have been reported in Indiana, Pennsylvania, Maine, Iowa and West Virginia. More than 50% of the cases that have been reported have come from the exposure to pigs, which is raising question that a variant of the swine flu might be now transferring from pigs on to humans.
http://topnews.net.nz/content/222213-ne ... t-emerging

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CDC tracking influenza strain that especially could impact children under 10 years old

April 16, 2012 | By Michael Johnsen

ATLANTA — Children under the age of 10 years old may be especially susceptible to a new strain of influenza, according to an article published Friday in the Center for Disease Control and Prevention's "Morbidity and Mortality Weekly Report."

As many as 12 infections with influenza A (H3N2)v, a variant virus with genes from avian, swine and human strains, that had been crossed with an influenza A (H1N1) strain have been tracked since August. Eleven of those cases occurred in children under the age of 10 years. And in six cases, no history of recent exposure to swine was noted, suggesting that human-to-human transmission had occurred.

The CDC conducted a preliminary analysis to evaluate the age-specific presence of serum cross-reactive antibody in U.S. populations vaccinated or not vaccinated with the 2010-2011 seasonal trivalent influenza vaccine. The results indicated that little or no cross-reactive antibody to A (H3N2)v exists among children under 10 years; that the 2010-2011 influenza vaccine had no impact on cross-reactive antibody levels in those under the age of 3 years; cross-reactive antibody was detected in 20% to 30% of those over 10 years old; and, among adults, vaccination with the 2010-2011 influenza vaccine provided a modest boost to the level of cross-reactive A (H3N2)v antibodies.

Receipt of seasonal influenza vaccine continues to be recommended to protect against circulating human influenza viruses for all age groups and might provide limited protection against A (H3N2)v infection in the adult population. A vaccine virus specific for A (H3N2)v has been developed and could be used to produce an H3N2v vaccine, if needed, the CDC reported.

Human infections with influenza A (H3N2)v were reported with increased frequency in 2011 compared with previous years, however enhanced surveillance might be a contributing factor, noted MMWR editors.

The composition of the 2011-2012 seasonal triumvirate vaccine is identical to the 2010-2011 vaccine evaluated in this report and is expected to provide limited cross-protection from A (H3N2)v in adults and no cross-protection in young children. In the event of sustained human-to-human transmission of (H3N2)v, an A (H3N2)v-specific vaccine would provide optimal protection for all ages. An A (H3N2)v reassortant vaccine strain based on the A/Minnesota/11/2010 virus has been developed and could be used to produce an H3N2v vaccine, if needed.

Updated information and guidance documents related to A (H3N2)v viruses are available online from CDC here.
http://www.drugstorenews.com/article/cd ... -years-old

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Contact "in the week preceding onset" is different than the local report by physicians in Weber county, Utah, who stated "The child had contact a week prior with swine at a family-owned slaughterhouse."

http://canyonviewmedical.com/blog/?p=195

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H3N2v podcast including Jackie Katz from CDC

http://podcasts.jwatch.org/index.php/po ... 012/04/14/

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