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Would an imperfect vaccine be useful in a flu pandemic?

first_imgApr 11, 2006 (CIDRAP News) – A mathematical modeling study suggests that a modestly effective vaccine could keep an influenza pandemic from striking more than 10% of the US population, but only if large amounts of vaccine were distributed quickly and the virus was not too highly contagious. The modeling study seems to lend some support to the US strategy of stockpiling a vaccine based on recent strains of H5N1 avian flu, which won’t precisely match an emerging pandemic strain. But the model incorporates many assumptions that may or may not prove accurate in the event of a pandemic, and experts note that very little H5N1 vaccine would be available if a pandemic occurred anytime soon. Germann TC, Kadau K, Longini IM, et al. Mitigation strategies for pandemic influenza in the United States. Proc Nat Acad Sci 2006 Apr 11;103(15):5935-40 [Abstract] Germann and two associates, Kai Kadau and Catherine A. Macken, all of Los Alamos National Laboratory, worked on the study with Ira M. Longini Jr., a biostatistician from the Fred Hutchinson Cancer Research Center and the University of Washington in Seattle. See also: “Aggressive” production and distribution of vaccine could control a pandemic with an R of less than 1.9, the model predicted. “We believe that a large stockpile of avian-based vaccine with potential pandemic influenza antigens, coupled with the capacity to rapidly make a better-matched vaccine based on human strains, would be the best strategy to mitigate pandemic influenza,” the authors write. “This effort needs to be coupled with a rapid vaccine distribution system capable of distributing at least 10 million doses per week to affected regions of the U.S.” Other experts who were asked to comment on the study had different reactions. Travel restrictions alone would accomplish little, according to the simulations. A 90% reduction in travel would slow the virus’s spread by only a few days to a few weeks, depending on transmissibility, and would not dent the ultimate size of the pandemic. Other control strategies used alone could limit a pandemic only if the virus had relatively low transmissibility (R of 1.6), the model predicted. For example, targeted use of antiviral drugs could succeed in that case, provided the supply was adequate and close contacts of patients could be quickly identified. But if R were 1.8, the nation would need a “prohibitively large” 51 million treatment courses of antivirals. Dr. Gregory Poland, a vaccine expert at the Mayo Clinic in Rochester, Minn., said the situation with the H5N1 vaccine being made for the US government points up the problems with the predictions. As was reported recently, the vaccine seems effective in about half of recipients, but it takes 12 times the dose used in seasonal flu vaccines, he noted. The study was supported by the National Institutes of Health (NIH). Its goals, the NIH said in a news release, were to determine how to slow the spread of a pandemic virus long enough to permit development and distribution of a well-matched vaccine and also how to limit the number of cases to less than 10% of the population, the percentage in an average flu season. The model projected that without any control effort and an R of 1.9, the virus would spread across the nation within 30 days of its first arrivals, that 122 million people would ultimately fall ill, and that the pandemic would peak in 85 days. With an R number of 2.4 and no control effort, as many as 151 million would get sick, according to the model. William Schaffner, MD, a hospital epidemiologist and professor in the infectious disease division at Vanderbilt University in Nashville, said he found the study reassuring, though he had not examined it closely. “The ultimate take-home line was that even a partially effective vaccine is an important part of the strategy,” he said.center_img For a highly transmissible virus (R greater than 1.9), it would take a combination of measures to limit the pandemic, the model predicted. For example, the combined use of vaccination, targeted antiviral use (3 million courses), school closures, social distancing, and travel restrictions could work at an R level as high as 2.4, the authors predict. With a moderately transmissible virus (meaning each case leads to fewer than 1.9 additional cases), “Our model suggests that the rapid production and distribution of vaccines, even if poorly matched to the circulating strains, could significantly slow disease spread and limit the number ill to less than 10% of the population, particularly if children are preferentially vaccinated,” says the report by Timothy C. Germann and colleagues. With a more contagious virus, additional measures such as school closings, travel bans, and antiviral drugs would have to be used in combination with vaccination, says the report published online last week by the Proceedings of the National Academy of Sciences. Michael T. Osterholm, PhD, MPH, a leading pandemic preparedness advocate, had a sharply different view of the study. “I think it’s based on a number of assumptions which in the real world won’t happen,” he said. “The idea that we’ll even have vaccine to consider in terms of dealing with the pandemic is at this point not likely for the vast majority of the world.” Osterholm, director of the University of Minnesota Center for Infectious Disease Research and Policy, publisher of the CIDRAP Web site, said “any number” of assumptions used in the model could be questioned. “I continue to worry that far too much credence is being put into theoretical models that lack reality testing in the likely world of a pandemic,” he said. “A moderately effective vaccine would work if you could get it into enough people,” said Poland, who directs the Mayo Vaccine Research Group and Program in Translational Immunovirology. “This current vaccine, if we used the whole world manufacturing capacity, offers enough doses for somewhere around 37.5 million people. So that’s not an answer.” He added that it may be necessary to make more than one vaccine, given the different clades (families) of H5N1 virus that have emerged. With a very limited supply of a vaccine for which two doses are recommended, the model showed it would be less helpful to vaccinate a given number of people with the two doses than to give just one dose to twice as many people. The model simulated the unfolding of pandemic flu in a US population of 281 million over 180 days. It factored in US census data about population distribution and commuting patterns and assumptions about the frequency of interpersonal contacts. It assumed that a few infected people would arrive from abroad each day at 14 airports in the United States. The researchers ran the simulations with four different reproductive (R) numbers (the number of additional people infected by each infected person), ranging from 1.6 to 2.4. He added that building up the capacity to treat the sick is important, but the main emphasis in pandemic preparedness should be on vaccination and other preventive measures. “The results [of the study] were so affirming of the general thoughts of the public health community that it’s really very reassuring, and I hope it stimulates further what I think is already a strong effort by HHS [the Department of Health and Human Services] to stimulate vaccine production and research on new ways to produce the flu vaccine and make better flu vaccines.” Poland also said no one knows how contagious the next pandemic virus will be. “My understanding is that the estimated R number for the 1918 pandemic was right around 3,” higher than the maximum of 2.4 used in the study, he said. “You wonder now if we truly have a novel subtype that’s easily transmissible, given the travel we have, if we wouldn’t have higher numbers. The average family is bigger than two people.” NIH news releasehttp://www.nigms.nih.gov/News/Results/FluModel040306last_img read more

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Former CIA officer speaks on information leaks

first_imgSpeaking before a small crowd of students in the Stauffer Science Hall, USC professor and former CIA intelligence officer Maura Godinez spoke about the issue of intelligence leaks, specifically in relation to Chelsea Manning — formerly known as Bradley Manning — who was convicted after releasing classified documents to the website WikiLeaks.The event was sponsored by the International Relations Undergraduate Association and the Center for Excellence in Teaching’s Undergraduate Fellows.“The CET wanted to do a speaker series because our goal is to increase collaboration between students and faculty and facilitate learning inside and outside the classroom,” said Nick Kosturos, a junior majoring in international relations and an undergraduate fellow in CET. “When we were approached by the IRUA with this opportunity, we agreed to provide funding and hope this will become the first of a faculty speaker series.”The event, “Manning: Soldier, Hacktivist, Leaker, Spy,” focused on the role of secrecy in government and under what, if any, circumstances leaking information is appropriate. Godinez began her talk by asking the audience to think about the definition of secrecy by considering some ethical case studies, such as publishing the names of those diagnosed with herpes simplex to prevent transmission of the disease. A theme she reiterated throughout the talk was the need to balance the desire of the leaker to expose wrongdoing with the interest of national security.“No matter what good a leaker may achieve, there is always, in the national security realm, some loss, and we must weigh that damage against the good the leaker hoped to effect,” Godinez said.Godinez also said that the threats arising from the leaking of information of any kind are real because foreign intelligence and terrorist organizations do not discriminate by source when gathering information about targets and, as a case officer, she personally utilized open source resources to build profiles of targets of interest.“These are learning organizations,” she said. ”They would not exist if they did not learn about us and modify their behavior to respond.”In addition, even if intelligence agencies are made aware of the scope and content of a                                                                                leak, replacing a leaked technological system, for example, can cost billions of dollars in lost research and development.She said that due to the complicated nature of security oversight, civil society has a large role to play in defining the appropriate role of secrecy. Godinez mentioned that traditionally, the legislative and judicial branches have exercised limited authority over the executive in matters of state secrecy because Congress is “made up of adversarial parties” and judges “don’t have depth or breadth of knowledge” in national security matters, so the personal virtues of the executive branch and the media play a significant role in regulating state secrecy.“There is an understanding among the intelligence community that information will come to the public eventually, and that serves as a check,” she said.Godinez also said the issue of leakers and whistleblowers was particularly complicated because of the need to separate the personal motivations of the leaker with the common interest of the country. She said that intelligence officials who have sworn oaths to secrecy cannot divulge information simply because their personal values have been violated; they would instead have to resign.If there is egregious wrongdoing and normal channels of redress have failed, Godinez said, then a truly altruistic leaker would expose the wrongdoing while taking steps to prevent a disproportionate threat to national security.During the discussion period, students weighed in on the actions of Manning, including the leaking of a video of  U.S. Marines in a helicopter, war logs from the operations in Iraq and Afghanistan and the release of hundreds of thousands of state department cables.“I didn’t know about the helicopter video and that was disturbing,” said Adela Jones, a junior majoring in interdisciplinary studies. “I was really surprised and really glad of the expertise of the students, and I was really glad that students were getting into it and thinking comprehensively about the issues.”Godinez said that it was important for citizens to debate these issues and provide guidelines for intelligence and military officials, as failing to discuss meant “abrogating” one’s right to pass judgement.“I think it’s good food for thought because we’re the next generation of voters and this is something to keep in the back of our mind to maybe pressure our elected officials about,” Jones said.last_img read more

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Health Minister denies appointment of new CEO at Diamond Hospital

first_imgDespite social media posts by Collin Haynes, a reported Alliance For Change (AFC) member indicating that he is the newly-appointed Chief Executive Officer of the East Bank Regional Hospital, commonly known as Diamond Hospital, Public Health Minister, Dr George Norton said no individual has yet been selected officially to fill the position.Subsequent to the post on Wednesday, speculation had been raised over the fact that Haynes, an overseas-based Guyanese, who has been residing in Maryland, USA for a number of years prior to his “appointment”, had been chosen over other individuals who are residents of Guyana.However, Dr Norton, during a telephone interview with Guyana Times, contradicted these claims by Haynes, confirming that there has not been any appointment made. He added that candidates who applied for the post were still being scrutinised by the committee to decide on who best fitted the position.The Minister added that while Haynes possessed the necessary qualifications for CEO, there were no assurances of whether or not he would be the selected individual.“There has not been any appointment of a CEO attached to the hospital even though he holds the qualifications needed. Currently, persons are still being considered for the post,” he affirmed.On Wednesday, which was said to be Haynes’ first day on the job, he had posted images on Facebook of him paying courtesy calls on families in Grove.He had even updated his profile’s biography to “Chief Executive Officer of East Bank Regional Hospital.”These were followed by a number of congratulatory messages from friends who commended Haynes for achieving the aforementioned position at the hospital.While the Minister did not indicate a specific time when the new CEO would take up the office at the hospital, he reiterated that the selection phase was still ongoing.last_img read more

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