새로운 독감이 유행할 준비를 갖추고 있는가?

미국의사협회지 (JAMA) 2012년 7월 11일자에 신증플루(H1N1) 예방접종 후 말초신경 장애를 초래하는 희귀질환인 길렝-바레 증후군이 발생할 수 있다는 보고가 실렸습니다.

캐나다 퀘백주에서 신종플루 백신을 접종받은 440만 명 중에서 25명에서  길렝-바레 증후군이 발생했으며… 100만 명 당 2명 꼴로 이 증상이 나타나는 것으로 추정됩니다.

그렇지만 연구진은 백신접종을 받지 않은 58명에게서도 길렝-바레 증후군이 나타났으며…
백신접종을 받지 않았을 경우의 위험이 길렝-바레 증후군이 발생할 위험보다 크기 때문에
백신접종을 받는 것을 권장하고 있습니다.



H1N1 vaccine may be linked to rare nerve disorder

By Christopher Wanjek

Published July 10, 2012 LiveScience
http://www.foxnews.com/health/2012/07/10/h1n1-vaccine-may-be-linked-to-rare-nerve-disorder/

The H1N1 (swine) flu vaccine was associated with a small but significant risk for developing a rare nervous disorder called Guillain–Barré syndrome (GBS), say doctors in a report detailed in the July 11 issue of  the Journal of the American Medical Association (JAMA).

The study, conducted in Quebec rekindles the still-controversial connection between Guillain–Barré syndrome (GBS) and the 1976 swine flu outbreak, which halted that year’s flu vaccination program in the United States. It also raises questions about vaccines for flu strains originating in swine.

This latest analysis, led by Philippe De Wals of Laval University, Quebec City, Canada, followed 4.4 million residents vaccinated against the H1N1 “swine flu” in late 2009. Over the next six months, 25 people who received the vaccine developed GBS. Across the Quebec province, however, another 58 people who were not vaccinated also developed GBS.

De Wals said that, regarding the entire population, the number of GBS cases attributed to the swine flu vaccine was about 2 per 1 million doses, but that the benefits of immunization outweigh the risks.

Vaccine risks and benefits

Health experts have long been nervous to speak about risks associated with vaccines. This is because the vaccine benefits are great and the risks are small, with adverse reactions usually occurring in vulnerable populations, such as those with certain allergies or pre-existing nervous system disorders. [5 Dangerous Vaccination Myths]

Flu vaccines, in particular, save millions of lives. Influenza will kill on average about a half-million people worldwide annually, including up to 40,000 in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC). Flu pandemics will kill millions.

Sometimes vaccine risks are real and high because of a bad batch of drugs. A prime example is the Cutter Incident in 1955, in which the polio vaccine accidentally contained a live virus that infected 40,000 children, leading to 55 cases of paralysis and five deaths. This nearly destroyed the public’s confidence in vaccines at the dawn of polio eradication.

Sometimes, however, reports of vaccine risks turn out to be false and based on fabricated science, such as the link between the measles, mumps and rubella (MMR) vaccine and autism. Measles and also whooping cough have had resurgences as a result of low vaccination rates brought on by this scare.

Thus, many health experts do not readily concede to vaccine risks when confronted with them. And Guillain–Barré syndrome haunts many like a specter.

Tale of two swine

Guillain–Barré syndrome is a serious peripheral nerve disease that can cause partial paralysis, breathing difficulties and death. Most patients recover after several months to a year, although not always fully. GBS is associated with Campylobacter jejuni,the food-borne bacterium, and several viruses; but for most cases, the immediate cause is not known, according to the CDC. [Top 10 Mysterious Diseases]

During the 1976 swine flu outbreak in the United States, health authorities reported an unusually high number of GBS cases, nearly 1,100 — half of which occurred after immunization against the flu. Panic ensued, and the vaccine program ended by December that year.

Doctors debated the connection then, and it took nearly 30 years before the prestigious U.S.-based Institute of Medicine concluded in 2003 that there was a causal relationship and that one extra person out of a million contracted GBS as a result of the vaccination.

The results of the new Quebec study on the 2009 H1N1 flu strain of swine origin are eerily similar to the conclusions drawn from the dozens of studies on the 1976 swine flu outbreak. Is there something about vaccines for flu strains of swine origin that can trigger GBS?

A much larger study published in February 2011 in the New England Journal of Medicine examined nearly 90 million doses of H1N1 vaccine in China and concluded that the answer was no.  Doctors there found only 11 cases of Guillain–Barré syndrome, which actually is far lower than the natural rate.

So, one debate will continue: whether there is a small but real link between swine flu vaccines and GBS. But few if any reputable doctors will argue that the flu vaccine is dangerous or not worthwhile for most people, from infants to the elderly. In fact, a study published in the same issue of JAMA finds the H1N1 vaccine is safe for pregnant women.

Read more: http://www.foxnews.com/health/2012/07/10/h1n1-vaccine-may-be-linked-to-rare-nerve-disorder/#ixzz20vfrSEOn

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[국내사례] 신종 인플루엔자(H1N1) 예방 접종 후 발생한 길렝 바레 증후군 1례
Journal of The Korean Child Neurology Society 2010 ; 18(1) : 108-111 

2009년 신종플루로 사망한 사람이 28만 4천5백명으로 추정되어 실험실 확진 사망자 수보다
15배나 더 많은 것으로 보인다는 연구결과가 <랜싯>지에 실렸습니다.

New mortality estimate for 2009 H1N1 flu pandemic

 Deaths worldwide from the 2009 influenza H1N1 pandemic were likely to be around 280,000, far higher than the 18,500 deaths reported from laboratory confirmed H1N1 influenza analysis, according to new research published in The Lancet Infectious Diseases. To reach this new global mortality estimate, the study investigators developed a new model that used influenza-specific data from 12 low, middle, and high-income countries. A separate study highlights how a H1N1 vaccination campaign was effectively implemented in Scotland, UK, during the pandemic, with implications for future pandemic preparedness.

=========================

The Lancet Infectious Diseases, Early Online Publication, 26 June 2012
doi:10.1016/S1473-3099(12)70121-4Cite or Link Using DOI

http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(12)70121-4/fulltext

Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: a modelling study

Dr Fatimah S Dawood MD a , A Danielle Iuliano PhD a, Carrie Reed DSc a, Martin I Meltzer PhD b, David K Shay MD a, Po-Yung Cheng PhD a, Don Bandaranayake MBBS c, Robert F Breiman MD d, W Abdullah Brooks MD e f, Philippe Buchy MD g, Daniel R Feikin MD d, Karen B Fowler DrPH h, Aubree Gordon PhD i j, Nguyen Tran Hien MD k, Peter Horby MBBS l, Q Sue Huang PhD c, Mark A Katz MD d, Anand Krishnan MBBS m, Renu Lal PhD a, Joel M Montgomery PhD a n, Kåre Mølbak MD o, Richard Pebody MBBS p, Anne M Presanis PhD p, Hugo Razuri MD n, Anneke Steens MSc q, Yeny O Tinoco DVM n, Jacco Wallinga PhD q, Hongjie Yu MD r, Sirenda Vong MD s, Joseph Bresee MD a, Dr Marc-Alain Widdowson VetMB a

Summary

Background

18 500 laboratory-confirmed deaths caused by the 2009 pandemic influenza A H1N1 were reported worldwide for the period April, 2009, to August, 2010. This number is likely to be only a fraction of the true number of the deaths associated with 2009 pandemic influenza A H1N1. We aimed to estimate the global number of deaths during the first 12 months of virus circulation in each country.

Methods

We calculated crude respiratory mortality rates associated with the 2009 pandemic influenza A H1N1 strain by age (0—17 years, 18—64 years, and >64 years) using the cumulative (12 months) virus-associated symptomatic attack rates from 12 countries and symptomatic case fatality ratios (sCFR) from five high-income countries. To adjust crude mortality rates for differences between countries in risk of death from influenza, we developed a respiratory mortality multiplier equal to the ratio of the median lower respiratory tract infection mortality rate in each WHO region mortality stratum to the median in countries with very low mortality. We calculated cardiovascular disease mortality rates associated with 2009 pandemic influenza A H1N1 infection with the ratio of excess deaths from cardiovascular and respiratory diseases during the pandemic in five countries and multiplied these values by the crude respiratory disease mortality rate associated with the virus. Respiratory and cardiovascular mortality rates associated with 2009 pandemic influenza A H1N1 were multiplied by age to calculate the number of associated deaths.

Findings

We estimate that globally there were 201 200 respiratory deaths (range 105 700—395 600) with an additional 83 300 cardiovascular deaths (46 000—179 900) associated with 2009 pandemic influenza A H1N1. 80% of the respiratory and cardiovascular deaths were in people younger than 65 years and 59% occurred in southeast Asia and Africa.

Interpretation

Our estimate of respiratory and cardiovascular mortality associated with the 2009 pandemic influenza A H1N1 was 15 times higher than reported laboratory-confirmed deaths. Although no estimates of sCFRs were available from Africa and southeast Asia, a disproportionate number of estimated pandemic deaths might have occurred in these regions. Therefore, efforts to prevent influenza need to effectively target these regions in future pandemics.

Funding

None.

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2009 swine flu outbreak was 15 times deadlier: study
By Sharon Begley | Reuters – 6 hrs ago

http://news.yahoo.com/2009-swine-flu-outbreak-15-times-deadlier-study-231455317.html;_ylt=A2KJjb32SulP2jIAXL7QtDMD

NEW YORK (Reuters) – The swine flu pandemic of 2009 killed an estimated 284,500 people, some 15 times the number confirmed by laboratory tests at the time, according to a new study by an international group of scientists.

The study, published on Tuesday in the London-based journal Lancet Infectious Diseases, said the toll might have been even higher – as many as 579,000 people.

The original count, compiled by the World Health Organization, put the number at 18,500.

Those were only the deaths confirmed by lab testing, which the WHO itself warned was a gross underestimate because the deaths of people without access to the health system go uncounted, and because the virus is not always detectable after a victim dies.

The new study also shows the pandemic’s impact varied widely by region, with 51 percent of swine flu deaths occurring in Africa and southeast Asia, which account for only 38 percent of the world’s population.

“This pandemic really did take an enormous toll,” said Dr. Fatimah Dawood of the U.S. Centers for Disease Control and Prevention, who led the study. “Our results also suggest how best to deploy resources. If a vaccine were to become available, we need to make sure it reached the areas where the death toll is likely to be highest.”

Swine flu, caused by the H1N1 influenza virus, infected its first known victim in central Mexico in March 2009. By April it had reached California, infecting a 10-year-old, and then quickly spread around the world, triggering fears and even panic.

The CDC warned Americans not to travel to Mexico if they could avoid it. Egypt ordered the slaughter of all the country’s pigs in a misguided attempt to contain the virus, which was in fact spread from person to person.

The fears reflected the unusual nature of the virus, which contained bits and pieces of bird, swine and human flu viruses, a combination never before detected.

Scientists were unsure how transmissible or deadly this mongrel flu would be, but early signs were ominous: the World Health Organization declared swine flu a pandemic in June 2009, when labs had identified cases in 74 countries.

Such lab-based identification is the gold standard, but every expert acknowledges that it misses more cases than it catches.

One reason is that “some people who contract flu do not have access to health care,” said CDC’s Dawood, so their illness and even death goes unnoticed by authorities. Another reason is that the virus is not always detectable by the time a victim dies.

LACK OF DATA LOWBALLS FATALITIES

To get around these obstacles, epidemiologists resort to statistical models. They typically take the number of deaths from pneumonia and complications of underlying cardiovascular disease – both caused by influenza – during non-flu periods, count the number during a pandemic, and attribute the excess to the flu.

Unfortunately, “vital statistics data are non-existent or sparse in many lower-resource countries,” said Dawood, making this approach infeasible.

Dawood and her colleagues – from Vietnam, Kenya, New Zealand, Denmark and five other countries – tried a different method.

They started with hard data, such as numbers from health workers going door to door in rural villages and asking about flu-like symptoms and testing nasal and throat swab samples, to estimate the proportion of a country’s population infected with 2009 H1N1. Such data were available from 13 countries – wealthy, such as Denmark, and poor, like Vietnam.

Then the scientists estimated the fraction of patients who died in each country. They started with solid data on death rates from respiratory illnesses in five wealthy nations.

Since someone with, say, pneumonia has a lower chance of dying if treated in a top hospital in Hong Kong than at a rural clinic in Vietnam, the scientists applied a “multiplier” to the raw data from poor countries.

That is, they assumed that more people with flu-caused pneumonia died in developing nations than developed ones.

These estimates and assumptions can introduce errors, critics note. Newly released mortality data from Mexico, for instance, show that H1N1 killed even more people than the new study estimates, said Lone Simonsen of George Washington University School of Public Health, co-author of a commentary on the study. Estimates of deaths from Japan and Singapore, in contrast, may be too high.

Overall, however, the under- and over-estimates probably even out, said Simonsen, making the global estimate – of 15 times more deaths than those confirmed at the time – about right.

The results paint a picture of a flu virus that did not treat all victims equally.

It killed two to three times as many of its victims in Africa as elsewhere. Overall, the virus infected children most (4 percent to 33 percent), adults moderately (0 to 22 percent of those 18 to 64) and the elderly hardly at all (0 to 4 percent).

Even though the elderly were more likely to die once infected, so few caught the virus that 80 percent of swine flu deaths were of people younger than 65.

In contrast, the elderly account for roughly 80 percent to 90 percent of deaths from seasonal influenza outbreaks. They were probably spared the worst of 2009 H1N1 because the virus resembled one that had circulated before 1957, meaning people alive then had developed some antibodies to it.

The relative youth of the victims meant that H1N1 stole more than three times as many years of life than typical seasonal flu: 9.7 million years of life lost compared to 2.8 million if it had targeted the elderly as seasonal flu does.

H1N1 had begun petering out by November 2009, and the WHO declared the epidemic at an end the following August.

(Reporting by Sharon Begley; Editing by Michele Gershberg and Xavier Briand)