To answer frequenly asked questions about the flu vaccine for the 2009-2010 season, WebMD speaks with CDC flu expert William Atkinson, MD, MPH.

Sept. 13, 2010 -- As the 2010-2011 flu season approaches, it's once again time for flu vaccination.

This year, the CDC advises just about everyone to get the vaccine. That raises questions. So does the inclusion of the H1N1 pandemic swine flu vaccine in the seasonal vaccine.

To answer the questions, WebMD spoke with flu expert William Atkinson, MD, MPH, of the CDC's National Center for Immunization and Respiratory Diseases.

The CDC now recommends the flu vaccine for just about everyone over age 6 months. But does everyone really need a flu vaccination?

Everybody can benefit from the flu vaccine. Up until 2009, it was recommended every year for everyone except for a small group of 18- to 49-year-old, non-pregnant people in good health. We just added that group. Everyone who does not want to get the flu can benefit -- and it certainly can save some people's lives.

I'm a healthy person. It's just the flu, why should I worry about it?

That's a very good question. The problem is that we have seen some severe illnesses and deaths in young, relatively healthy people. Some were adults under age 50 who weren't aware they had risk factors for severe flu illness.

It is true that most flu deaths and severe illnesses occur in the extremes of age, in infants and in the elderly. But it does kill people who are healthy. And some people who think they are healthy have medical risks they are unaware of.

Even someone with no underlying medical condition can get a very nasty flu illness, with missed days of work and a trip to the doctor's office. Why would anyone want that?

In addition, vaccination of healthy people reduces their chance of becoming infected with the flu virus -- and passing the virus to someone at higher risk of complications, such as a baby or an elderly person.

I got a flu shot a few years ago -- and a few days later I came down with the flu. Instead of risking this again, wouldn't I be safer just avoiding sick people?

Probably one of the most common concerns we hear is from people who, right after getting a flu shot, got something that seems to them like flu.

It is possible it could happen. After a dose of flu vaccine, it takes at least a week to become immune. If flu is in your community and you are exposed, it takes two or three days for symptoms to appear. So it is possible if you are exposed to flu to get sick before the vaccine has a chance to work. It gives people the impression the vaccine caused the flu.

And the way people use it, "flu" is not a specific term. People have different ideas of what flu is. Other kinds of viral infections can cause a flu-like illness, but it is not flu. And influenza vaccine will not protect against that.

Keep in mind that the flu shot cannot produce a flu infection. It is dead -- it's just protein, with nothing live in it. So a lot of this is just coincidence -- either the vaccine did not have time to work, or you got something like the flu.

But this is a very common perception, linking your flu shot to getting the flu. Even some doctors and nurses have this perception.?The way our brains work is to have two things happen in sequence, and to conclude that the two things are connected by cause and effect. Vaccination is memorable, and the illness is memorable, and it is human nature to think one caused the other. But it is a perceptual problem rather than reality.

What about the FluMist inhaled vaccine? Isn't that a live virus? Can't that give me the flu?

FluMist is a really good option for people who are healthy and under 50 and not pregnant. It is live, but it has been modified so it only grows in a person's nose or throat. It does not get down into the lung. It is modified so it does not cause lung infection.

This means the virus in FluMist does not cause flu the way we think of it as a respiratory infection. It can cause a sore throat for a day or two, but not flu with cough or fever. It really does not do that.

Flu season again? I got my shots last year and the year before. Why do I need another one?

The problem is the flu virus: It changes all the time. This means we have to change the vaccine all the time to keep up.

Last year's vaccine is not like this year's vaccine. There are three different viruses that can cause flu. Vaccines that protect against each one are included in the 3-in-1 seasonal flu vaccine. One or more of these components is changed every year because the virus we are trying to prevent has changed.

Unfortunately, being immune to one of last year's viruses may not protect you against this year's virus. It is a constant job of catch-up. And there probably is some waning of immunity over time, too, particularly with the shots.

Researchers are looking for a way to make a vaccine that is not so sensitive to change in the virus. We are looking for a one-shot vaccine that will protect for years after a single dose. That is what we would all like, a flu vaccine you could get every five or 10 years. But that vaccine has yet to be invented.

I got the flu during the swine flu pandemic. Do I still need this year's seasonal flu vaccine?

Yes. If you really had the flu during the pandemic, you probably are immune to the H1N1 swine flu. But there are other infections that can mimic influenza, and it could be some other virus that made you sick. Not all infections that act like flu are necessarily flu.

Probably millions of people were infected with the 2009 H1N1 flu strain. But we can't tell which person had swine flu and which had something like flu -- unless they really had a viral-culture test to prove they really had H1N1 virus.

Even then, remember, there is protection against two other flu viruses in this season's vaccine. If you went through having the 2009 H1N1 "swine flu," you certainly don't want to get sick again.

And there's a bonus for people who had an H1N1 infection last year: It will boost their immune response to the H1N1 component of the seasonal vaccine, and they will get additional immunity from the other two components of the vaccine.

I hear the H1N1 swine flu vaccine is included in the seasonal vaccine. Doesn't that make the seasonal vaccine much less safe?

The CDC and the FDA did an enormous amount of monitoring of the 2009 H1N1 swine flu vaccine. After tens of millions of doses, we have no evidence that vaccine was any less safe than any of the vaccines we have used for years.

Our monitoring showed the side effects of the H1N1 vaccine were pretty much the same as you'd see from regular seasonal vaccines. There was no indication the pandemic vaccine was any less safe than any vaccine we've ever produced.

So including that vaccine as one of the three in this year's seasonal vaccine will not change the safety pattern. Even so, we will monitor the safety of this year's seasonal vaccine closely-- as we always do.

My children are under 9 years old. How many doses of the seasonal flu vaccine do they need?

It's really quite complicated for parents whose children are 8 years old or younger and who have never been fully vaccinated against the flu.

How many doses of flu vaccine will a child under age 9 years need this year? It will depend on two things:

  • Whether the child got any H1N1 vaccine AND
  • Whether the child previously got a seasonal vaccination, when that was given, and how many doses they got.

Children who got a previous seasonal flu vaccine as recommended -- AND got just one dose of the H1N1 pandemic vaccine last year -- need only one dose of the seasonal vaccine this year. We give them credit for getting the priming dose last year, but only if they previously got the seasonal vaccine.

Children under age 9 years who never before got a seasonal flu vaccination will need two doses of the seasonal vaccine this year -- even if they got the 2009 H1N1 pandemic flu vaccine.

Children under age 9 years who have had a previous flu vaccination but who did not get the 2009 H1N1 pandemic flu vaccine will need two doses of the seasonal vaccine this year.

If a child needs two doses of the flu vaccine, the second dose must be given no sooner than four weeks after the first dose.

It's such a hassle to get young children two doses of flu vaccine a month apart. Won't they get at least some protection from a single dose of the vaccine?

No.

This year, the number of doses is driven by the pandemic virus component of the vaccine. Studies at the National Institutes of Health show that children do not respond well to a single dose of the 2009 H1N1 vaccine. A single dose does not provide protection to a very large number of young children.

We are not just making this up. The data show two doses are absolutely necessary. Yes, it can be a hassle to take them back a month later for their second dose -- but it greatly improves the chances the child will be protected.

I'm pregnant. Why should I risk getting a flu shot?

The risk is actually in not getting a flu shot.

We know pregnancy changes a healthy woman's risk of severe flu illness. We had a number of pregnant women die last year of flu.

Pregnancy and flu are a bad combination. Pregnancy increases the risk that a healthy woman who gets the flu will get sick, be hospitalized, or die.

Because the flu shot is only a protein that can't give a person the flu, the benefit of vaccination far outweighs any possible risk from the vaccine itself. That goes for the woman as well as for her developing baby .

We do have 50 years of experience giving the flu vaccine to women who are or who become pregnant. We have never had the slightest indication -- no indication at all -- that it could somehow be harmful to the developing baby. With billions of doses given, there is not a shred of evidence the vaccine is harmful to the fetus. It is all benefit; there seems to be no risk at all.

And is there any benefit for the baby? It is worth saying that in addition to protecting the mother, there is some research that suggests babies born to vaccinated women are less likely to get the flu in their first 6 months of life. And infants who get the flu are at very high risk of severe complications.

I'm breastfeeding. I know babies under age 6 months should not get the vaccine. If I get the vaccine, won't it put my baby at risk?

The reason the flu vaccine isn't recommended for infants under age 6 months is that not many studies have been done to see if it is safe and effective in babies that young.

But if the vaccine is given to a woman who is breastfeeding , it will protect the mother. It might also indirectly protect the baby, too, because the mom won't get sick and the infant won't get the flu from its mom. And flu vaccine given to a breastfeeding woman poses no risk to the baby.

I'd like to add that we try to "cocoon" a young infant against getting the flu. We try to make sure everyone in the infant's household is vaccinated, so they will not bring the flu home to children too young to be vaccinated themselves.

I'm allergic to eggs. Is there some form of the flu vaccine I can take?

The answer is no. There is no flu vaccine option for people with extreme allergy to eggs.

We are held hostage by chickens every year because, in the U.S., all our flu vaccines are produced in eggs. This means that there is no non-egg-based flu vaccine here.

But in the next five years it's likely we will have one. Instead of producing the vaccine in eggs, it can be produced in tissue cultures. We don't think twice about other vaccines that are raised in tissue culture, so why not flu vaccine?

WebMD Health News 
by Daniel DeNoon 
Reviewed By Laura Martin

Last Modified: 2010/9/13 下午 04:32:40

c 2010 WebMD, LLC. All rights reserved.

 

CDC希望你暸解的2010-2011流感疫苗相關問題

 

  【24drs.com】Sept. 13, 2010 – 隨著2010-2011年流感季節將近,施打流感疫苗的時機再度來臨。今年,疾病管制中心(CDC)建議每個人都接種疫苗,這引起了一些問題,例如是否將H1N1新流感病毒疫苗納入季節性疫苗。
  
  為了回答這些疑問,WebMD訪問了流感專家、CDC所屬之全國免疫暨呼吸道疾病中心的William Atkinson博士。
  
  CDC的新建議是,每個6個月以上的人都要接種疫苗,但是,每個人都真的需要打流感疫苗嗎?
  每個人都可以從流感疫苗獲益。至2009年為止,每年都建議除了18-49歲、健康且未懷孕者之外,都要接種疫苗。我們只是把這群人納入,每個不想罹患流感的人都可以獲益 –這當然可以挽救某些人的生命。
  
  我是健康的人,我需要擔心流感嗎?
  這是個好問題,問題是,曾經發生年輕、健康者之重症和死亡的案例,有些50歲以下者未警覺自己有流感重症的風險因素。
  
  的確,多數流感死亡和重症發生在嬰兒和老人,但是,確實也曾讓健康者喪命,有些自認為健康者有醫療上的風險而不自知。
  
  即使是原本沒有健康問題者也可能發生相當難纏的流感,需請病假就醫,有人想要這樣嗎?
  此外,健康者接種疫苗可減少被流感病毒感染的機會—也避免將病毒傳染給風險更高者如嬰兒或年長者。
  
  我幾年前打過流感疫苗—幾天後我發生流感,為了避免再度發生此風險,我是否只要避免和病患接觸就可以比較安全?
  或許,我們最常聽到的顧慮是,有些人在接種流感疫苗之後立即發現似乎發生流感。
  
  這是有可能發生的,施打一劑流感疫苗後,須至少一週才有免疫,如果你曝露在有流感的社區,只要兩、三天就會發生症狀,所以,如果你在接種疫苗前就已經曝露於流感環境中,是有可能在接種後發現自己生病,這造成人們「疫苗會引起流感」的印象。
  
  再者,「流感」並非特定名詞,人們對流感的看法不一。其他病毒感染可能引起「類流感症狀」,但是卻非流感,流感疫苗無法預防這種情況。
  
  要記住,流感疫苗不會產生流感感染,那是死菌疫苗、只是些蛋白質,沒有任何活性。所以,不論是疫苗沒有即時生效或者你好像得到流感-都只是巧合。
  
  但是,認為接種流感疫苗和得到流感之間有所關聯是很常見的觀念,甚至有些醫護也有此觀念。我們的邏輯是有先後順序的兩件事情之間可能有因果關係,施打疫苗和生病都是令人難忘的,認為有所關聯也是人之本性,但是,那只是認知問題而非事實。
  
  有關FluMist吸入型疫苗是怎樣?它是活的病毒嗎?會不會讓我得到流感?
  FluMist對於50歲以下且未懷孕的健康者是很好的選項。它是活的病毒,但是,經過修飾使其只可以在人的鼻子或喉嚨生長,不會進入肺部,因此不會引起肺部感染。
  
  這意味著FluMist中的病毒不會引起流感般的呼吸道感染,它會引起一、兩天的喉嚨痛,但是,不是像流感般的咳嗽或發燒,它真的不會如此。
  
  流感季節再度來臨,我去年和前年都打過針,為何我還需要再接種?
  問題在於流感病毒一直在改變,這表示我們必須隨時變動疫苗內容才得以因應。
  
  去年的疫苗和今年的不同,有3個不同的病毒引起流感,納入三合一季節性流感疫苗中對抗這幾個病毒。其中的組成之一或以上,會每年改變,因為我們希望預防的病毒改變。
  
  不幸的是,對去年的病毒產生免疫不等於對今年的病毒免疫,每年施打變成例行公事。或許,免疫力也會隨著時間降低,特別是這些疫苗。
  
  研究者正尋找製造一種對病毒變化沒那麼敏感的疫苗的方法,我們希望找到一種打一劑之後可以有幾年保護力的疫苗,這將是我們所樂見的:每10年打一次的流感疫苗,但是,還沒發明這種疫苗。
  
  我罹患過新流感,我仍需要接種季節性流感疫苗嗎?
  是的,如果你在大流行時得過流感,你或許對H1N1新流感有免疫力,但是,還有其他引起流感的病毒會讓你生病,並非所有類似流感的感染就必定是流感。
  
  或許有數百萬人被2009年的H1N1流感病毒感染,但是,我們無法分辨哪些人得過新流感、哪些人是類流感—除非他們真的有病毒培養試驗來證明他們真的有H1N1病毒。
  
  記住,即使如此,季節性流感可以對其他兩個流感病毒提供保護力,如果你經歷過2009年的H1N1新流感,你肯定不希望再度生病。
  
  去年發生過H1N1感染者有另一個利多:可以加強季節性流感中H1N1成份的免疫反應,也可從疫苗中的另外兩個成分獲得免疫力。
  
  我聽說H1N1新流感疫苗被納入季節性流感疫苗,這不會導致季節性流感疫苗比較不安全嗎?
  CDC和FDA都對2009年H1N1新流感疫苗進行了大量的監測,在施打幾千萬劑之後,並未發現該疫苗有比使用多年的疫苗更不安全的證據。
  
  我們的監測發現,H1N1疫苗的副作用大多和一般的季節性流感疫苗相似,並未發現這個疫苗比任何曾經使用過的疫苗更不安全的證據。
  
  所以,將這疫苗納入今年的季節性疫苗的三個成分之一,並不會改變這個安全模式,不過,我們將一如往例,密切監測今年季節性疫苗的安全性。
  
  我的小孩未滿9歲,他需要幾劑季節性流感疫苗?
  對於家中有未曾接種過完整抗流感疫苗之8歲以下小孩的家長而言,這的確是相當麻煩。
  
  9歲以下小孩需要多少劑的流感疫苗,須依據以下兩點:
  * 這小孩是否曾接受過任何的H1N1疫苗,而且
  * 這小孩是否曾經接受過季節性疫苗,若有,接種過幾劑。
  
  曾接受過季節性流感疫苗建議劑量、且去年接受過一劑H1N1疫苗的小孩—今年只需要一劑的季節性流感疫苗,我們相信他們在去年得到基本的劑量,但是,前提是他們曾接受過季節性疫苗。
  
  未曾接受過季節性流感疫苗的9歲以下小孩,今年將需要兩劑的季節性流感疫苗—即便他們曾接受過2009年H1N1流感疫苗。曾接受過季節性流感疫苗、但未曾接受過2009年H1N1流感疫苗的9歲以下小孩,今年將需要兩劑的季節性流感疫苗。
  
  如果小孩需要兩劑的流感疫苗,第二劑須和第一劑間隔四週。
  
  讓小孩的兩劑流感疫苗間隔一個月這點有所爭論,單一劑量的疫苗不會至少有一些保護力嗎?
  不會!
  
  今年,劑量數是根據疫苗中的大流行病毒組成而定。國家健康研究中心的研究顯示,孩童對於單一劑量的2009年H1N1流感疫苗反應不佳,單一劑量無法提供多數幼童的保護力。
  
  不只如此,資料顯示,兩劑是絕對必要。是的, 要他們一個月後回來接種第二劑是有所爭論—但是,這大大改善了小孩獲得保護的機會。
  
  我懷孕了,我接種流感疫苗有何風險?
  風險實際上來自未接種流感疫苗。
  
  我們知道,懷孕讓婦女變成有流感重症風險,去年有許多孕婦死於流感。
  
  懷孕和流感相剋,懷孕增加了健康婦女發生流感且重症、住院或死亡的風險。
  
  因為流感疫苗只是蛋白質,不會讓人發生流感,接種疫苗的好處大於疫苗本身的任何可能風險,對於婦女和腹中胎兒也是如此。
  
  對於讓孕婦或即將懷孕之婦女接受流感疫苗,我們有50年的經驗,未曾發生過對於發育中的胎兒有所傷害。在給過的數十億劑劑量中,毫無證據認為疫苗對胎兒有害。它是完全有益的;一點也沒有風險。
  
  對嬰兒有任何幫助嗎?可以說是,除了對母親的保護之外,有一些研究認為接種疫苗之母親所生下的嬰兒在生下後6個月內比較不會罹患流感;嬰兒若發生流感,則嚴重併發症的風險相當高。
  
  我在哺乳,我知道6個月以下的嬰兒不應接受疫苗,如果我接受疫苗,會不會讓我的嬰兒有風險?
  流感疫苗不建議用於6月個以下嬰兒的理由是,有關其安全性和有效性的研究不多。
  
  但是,如果是哺乳婦女接種疫苗,對母親有保護力,或許也會間接保護嬰兒,因為母親不會生病,嬰兒也不會被母親傳染流感,哺乳婦女接種流感疫苗不會對嬰兒有風險。
  
  我想提出的是,我們試著讓幼嬰納入對抗流感的防護罩中。我們試著確保有嬰兒之家庭的成員每個都接種疫苗,以免他們將病毒傳染給家中尚無法接種疫苗的嬰幼兒。
  
  我對雞蛋過敏,有我可以用的其他類型流感疫苗嗎?
  答案是沒有。對於雞蛋非常過敏者,沒有可用的流感疫苗選項。
  
  在美國,我們每年都得仰賴用雞蛋製造疫苗,所有疫苗都是在雞蛋中生產,這表示目前沒有非雞蛋型的流感疫苗。
  
  但是,未來5年內,可能會有一線希望,除了在雞蛋生產疫苗之外,可望在組織培養中產生,我們對於在組織培養中產生疫苗不感猶豫,所以,流感疫苗將不無可能!

 

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