This is an update written on October 1 to an article previously published on September 18, 2009.
The H1N1 flu vaccine will be available to the US public around October 6. Influenza activity, much of it H1N1, has been increasing the past few weeks in the US, so this is welcome news for all of us: individuals now have an option for protection from an unpleasant illness, health care providers have a new treatment to offer their patients, and anti-vaccine wingnuts finally have some fresh material. Here’s some answers to common questions about the H1N1 vaccine.
What is the H1N1 flu vaccine and is it different from the seasonal flu vaccine?
The H1N1 vaccine and the seasonal flu vaccine are two separate vaccines against different viruses. Health care professionals recommend that certain people get both vaccines.
The H1N1 vaccine protects only against the new H1N1 influenza virus, which is the cause of swine flu. It does not protect against other strains of seasonal flu. The seasonal flu vaccine, offered every year, provides protection against an additional three common influenza viruses. Both vaccines are expected to reduce illness, limit hospitalizations, and potentially save lives.
When will the H1N1 flu vaccine and the seasonal flu vaccine be available?
According to the CDC, the first doses of the H1N1 vaccine will ship in early October and be available to the public around October 6. This initial version is the nasal spray. The injectable vaccine will ship soon after.
The seasonal flu vaccine is already available, as a nasal spray and as an injection.
What is the difference between the injected H1N1 vaccine and the nasal spray H1N1 vaccine?
The injected H1N1 vaccine contains viral proteins-it does not contain an actual live virus. The nasal spray contains live, weakened virus.
Due to production issues, the nasal spray vaccine will be available before the injectable vaccine. Unfortunately, since the nasal spray vaccine contains a live virus, it is only recommended in healthy individuals between the ages of 2 and 50. People older than 50 and people with chronic underlying medical conditions should wait for the injectable vaccine.
Who should get the H1N1 flu vaccine?
Vaccine experts recommend that high-risk groups get vaccinated against the illness. This includes:
● Pregnant women
● Healthcare providers
● People aged 6 months through 24 years
● People who are around infants less than 6 months old
● Anyone with a chronic health condition that increases their risk of severe illness. Such chronic conditions include but are not limited to asthma, heart disease, emphysema, diabetes, and a weakened immune system.
This includes about 159 million Americans, chances are good you’re one of them.
Though the focus should be on high-risk groups, experts recommend that anyone who wants the vaccine should get it, provided there is enough leftover supply for the general population.
Who should not get the H1N1 flu vaccine?
Anyone with an allergy to eggs should not receive the vaccine, since chicken eggs are used in the manufacturing process for both the nasal spray and the injectable vaccine. Children less than 6 months should not get the vaccine (instead, people around them should get the vaccine so they are protected).
For adults over 65, the seasonal flu vaccine is highly recommended, but the recommendation for H1N1 vaccine is not as strong. For reasons that are currently unclear, older adults are less likely to suffer severe illness from H1N1 as compared to younger adults, perhaps due to a certain amount of immunity from prior exposure decades ago.
Who should receive the H1N1 injection vaccine instead of the nasal spray vaccine?
Basically, healthy people between the ages of 2 and 50 can get the nasal spray, anyone else should get the injection. Especially if you have a weakened immune system, you should not receive the live virus nasal spray; get the injection with the killed virus instead. Children who need long term aspirin therapy, such as for conditions like Kawasaki disease, should also receive the injection instead of the nasal spray.
Can I get the H1N1 flu vaccine at the same time as the seasonal flu vaccine?
You can get both injections at the same time. However, if you’re using the nasal spray, you should separate the two by about one month.
How many doses of the H1N1 vaccine do I need?
Adults need just one dose of the vaccine. Children under 10 years need 2 doses separated by a month in order to get a good immune response.
What are the side effects of the H1N1 vaccine?
Similar to the seasonal flu vaccine, the most common side effects of this injectable vaccine are pain at the injection site, muscle aches, headaches, and malaise. Rarely, patients might suffer severe allergic reactions to the vaccine.
The nasal vaccine’s side effects include runny nose, sore throat, and fevers-symptoms that resemble a very mild case of the flu, but are not nearly as severe or long-lasting as a real influenza infection.
The best data about this vaccine come from two studies recently published in the New England Journal of Medicine. Several hundred adult patients who received the vaccine have been followed for months, and initial data was published several weeks after vaccination. No serious short-term side effects were found in any of those patients.
Since the nasal spray vaccine is a live virus, can I catch the flu from it?
No. The nasal spray vaccine contains live, attenuated viruses that are cold-adapted. This means that they can live in the relatively cooler temperatures of the nose, but not warmer places deep in the body, such as in the lungs. Because they are limited to the nose, the effects of the virus are mild. Some people do get side effects that resemble a very weak, short-lived flu, but are nowhere near as serious as a real influenza infection.
Will getting the seasonal flu vaccine increase my risk of catching swine flu?
It’s unlikely. Media in Canada are reporting on a study purportedly showing that individuals who got the flu shot in 2008 are more likely to catch H1N1 in 2009. This study has not been published in any scientific journal, so no one knows if it’s accurate. According to Dr. Thomas Freiden from the CDC, investigators have closely looked at data from New York and Australia for similar results, and no increased risk was seen. At this point, all the reliable data and studies that have been published do not show any increased risk of catching swine flu after getting the seasonal flu vaccine.
What is the current status of research on H1N1 vaccine?
As of September 30, several studies of hundreds of healthy adult patients have been published. Research is ongoing in children and pregnant patients.
The H1N1 vaccine is manufactured using the same process as the seasonal flu vaccine, by the same manufacturers in the same factories. Years of research with the seasonal flu vaccine, including research in pregnant patients and children, have shown it to be extremely safe.
What is Guillain Barre Syndrome and why are people talking about it when they’re talking about the H1N1 flu vaccine?
Guillain Barre Syndrome is a rare neurological illness with symptoms ranging from mild muscle weakness to complete paralysis. While most people recover, some people die from the illness. Triggers for the disease include infections, most commonly by a bacteria called Campylobacter.
The influenza virus itself can also cause Guillain Barre Syndrome, and there is some debate about whether the seasonal influenza vaccine causes the disease. If the vaccine does increase the risk, the increase is very slight at about one case per million people vaccinated. The odds of developing a severe complication such as pneumonia from an influenza infection are higher than that, so even if the vaccine does cause Guillain Barre Syndrome, you’re better off getting the seasonal flu vaccine.
Unlike the controversial link between the Guillain Barre Syndrome and the seasonal influenza vaccine, there is a likely association between the syndrome and a previous swine flu vaccine. According to the CDC, the 1976 swine flu vaccine caused about one case of Guillain Barre Syndrome for every 100,000 people vaccinated.
The 1976 swine flu vaccine which resulted in an increased risk of Guillain Barre Syndrome was manufactured using different techniques than the current H1N1 vaccine. Since the current H1N1 vaccine is produced with the same process as the seasonal influenza virus, the risk of Guillain Barre Syndrome is thought to be similar to the very low or negligible risk from the seasonal influenza vaccine.
Is mercury (thimerosal) included in the vaccines?
Some, but not all, of the batches of H1N1 vaccine are thimerosal-free.
Thimerosal is a mercury compound that is added to multi-dose vials of influenza vaccines to prevent bacterial contamination of the medication. Some groups have questioned whether mercury in vaccines plays a role in the development of autism, but scientific studies have shown no correlation between thimerosal and autism.
Are adjuvants included in the H1N1 vaccines?
No. None of the current H1N1 vaccines marketed in the US contain adjuvants.
Adjuvants are additional materials that are added to the antigen in a vaccine to make it more effective. Adding these materials, such as small doses of aluminum, will increase your body’s immune response to the vaccine.
I’ve already had H1N1, should I get the vaccine? If I do, will it harm me?
If you’ve already had H1N1, there’s no point in getting the vaccine. However, if you do get the vaccine, it will not harm you-on the other hand, it won’t help either.
Many people have had flu-like symptoms over the past several months and wonder if it was H1N1, realizing that if it was, there’s no point to getting the H1N1 vaccine. Since most people who have had upper respiratory infections in the past few months did not actually have H1N1, the CDC is recommending that they still get the vaccine against H1N1. This is especially true for people in one of the high-risk groups mentioned above.
H1N1 doesn’t seem to be that lethal, I’m young and healthy, should I really get the H1N1 vaccine?
The CDC recommends that young, healthy people get the vaccine if there is supply available after vaccinating high-risk groups. Overall, H1N1 does not appear to be particularly more deadly than the seasonal flu, but there is a higher rate of infection in younger people. It also appears that young, healthy people make up a higher percentage of the deaths from H1N1 than is typical for seasonal flu. While the chances of you dying from this disease are small, the chances that you will get infected and sick enough to stay home from school or work for a few days is much higher. The vaccine could prevent both illness and death.
You’ll have to weigh these known benefits from the vaccine versus the unknown risks. Initial studies of a few hundred adults have shown no danger from the vaccine in the short-term. In the long-term, since the vaccine is made using the same techniques as the seasonal flu vaccines, the H1N1 vaccine is expected to be equally safe.
Is it possible that these recommendations will change?
Yes. While the CDC’s recommendations are based on the best evidence available, the H1N1 situation is fluid and new recommendations might be made as more information is known.
Should the virus suddenly become more lethal, the recommendation to vaccinate young, healthy adults will become stronger. If the rates of H1N1 infection are declining in the US by the time the H1N1 vaccine is introduced, the recommendation to vaccinate might become weaker. I will continue to update this webpage as more is learned.
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Gregg A. Miller
Gregg Miller, MD is a board-certified emergency room physician. Not nearly as good-looking as the doctors on the TV show ER, lacking the charisma of Dr. House, and much less scandalous than anyone on Grey’s Anatomy, he still managed to carve out a niche ...
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Gregg A. Miller says:
Hi Gen,
In general, close family members of pregnant women can get the nasal spray vaccine, but pregnant women should get the shot, not the nasal spray. I can't give you specific advice for your particular family members, but I hope that general information helps. Congratulations on the pregnancy!
Gregg
Gregg A. Miller says:
If you're looking for an answer that's not provided in my article, please post it here and I'm happy to answer it if I can. Two caveats--first, I can only provide general information, not specific medical advice for a patient; and second, I don't frequently check this blog, so if you need a quick answer maybe you can find it in the links below:
H1N1 vaccine
http://www.cdc.gov/h1n1flu/vaccination/public/vaccination_qa_pub.htm
H1N1 vaccine and pregnancy
http://www.cdc.gov/H1N1flu/vaccination/pregnant_qa.htm
Regular flu vaccine and children
http://www.cdc.gov/flu/protect/children.htm
Regular flu vaccine
http://www.cdc.gov/FLU/protect/keyfacts.htm
jenny singh says:
Can I get the h1n1 flu virus if I have already gotten the h1n1 vaccination? How effective is it?
Gregg A. Miller says:
Hi Jenny,
Great question, and unfortunately no great answers. We won't know for sure how effective this vaccine is until the flu season is over and we can study the results of the H1N1 vaccine.
However, doctors expect the H1N1 vaccine to be similar in efficacy to the regular annual flu shot. The efficacy of the annual flu shot is determined by how well it matches that year's particular strain of flu virus--since the flu shot has to be made well in advance of the flu season, there's some educated guesswork, and the guesses aren't always right. In the years where the educated guesses are correct, the flu shot offers about 80% protection against catching the flu, in the years where the flu shot doesn't match the circulating strain of flu very well, the protection is about 50%.
So our best guess is that the H1N1 flu shot, which appears to be very well matched to the H1N1 virus that's circulating this winter, will be about 80% effective--that means that if everyone gets the shot, for every 100 people who were originally going to catch the flu, only 20 of them actually will get it.
If vaccination rates are very high, then that number might be even better. Due to herd immunity, some of those 20 vaccinated people who were going to get the flu will never be exposed to the virus since everyone around them is protected. Getting the vaccine not only protects you, it protects the people around you as well.
Gregg
Faye says:
No one is saying if people with allergic reactions to antibiotics (such as Sulfa drugs) should get the H1N1 vaccine. I am allergic to Sulfa (and several other antibiotics) and have read that Gentamicin is present in the vaccine. Is this true? And to what degree? Can it harm people with antibiotic allergies?
Gabby says:
Hey Gregg,
I have been hearing a lot about how cancer is becoming a new long term side-effect.
I looked it up, and have not found one educated article that includes cancer in the article at all.
I went to Pubmed.com as well as searched through some search engines for articles.
My question to you is; Is cancer likely as a side-effect, and if so, in what age group, and what is the estimated time till you would get cancer?
Sara says:
I have already had the H1N1 flu, and one of my daughters has it right now. There is a vaccination clinic that will be held at my children's school next month, but I am not sure whether they will benefit from the vaccine considering they will most likely be exposed to it, if not sick from it before then.
Should people get the vaccine if they have already had the H1N1 virus?
Should people get the vaccine if they have been recently exposed to it?
Stephanie says:
I'm a little worried about getting this vaccine. I've heard that they dont know the long term effects for it? Although i dont want to get sick, i also dont want something bad to happen from this vaccine.
brooke says:
what is this vaccine made of?
andy says:
Just wanted to confirm that since my 4 year old daughter (and 41 year old wife) are just at the end of their doctor diagnosed/tested H1N1 infection, that they don't need to bother getting the shot anymore? Somehow i managed to not get infected.... yet.
Logan says:
Hi Dr. Miller,
This may seem strange, but I am a 13 year old who is very concerned about my health. Yesterday, at an annual physical, I received the H1N1 flumist. I have heard of getting mild H1N1, due to the fact that they are giving you a live virus. Well, I think I may be one of that unlucky bunch. I have a very bad cough, yet it is not quite as severe as bronchitis. I have a fever that keeps leaving and returning. I am physically fit, yet, I am very fatigued, and climbing a stair case feels like climbing Mt. Everest. These symptoms hit me hard this morning, yet I was fine yesterday. Am I one of those who have this watered-down form of H1N1? I know you can't answer specifics, but please help, I have already consulted with my pediatrician, and we are still unsure.
Thank you,
Logan
gregg a. miller says:
Hi Faye,
Trace amounts of antibiotics are present in seasonal flu and H1N1 vaccines, since they are used to purify the vaccine and prevent bacterial infections. Different manufacturers use different antibiotics, including gentamicin, neomycin, and polymixin. If you’re allergic to the antibiotic in the vaccine, it’s usually not recommended to take the vaccine.
You can ask your doctor/nurse to look up this information from the package insert in the specific vaccine that you’re getting, or you can look it up the H1N1 vaccine inserts here:
http://www.immunize.org/packageinserts/pi_h1n1.asp
and the seasonal flu vaccine inserts here:
http://www.immunize.org/packageinserts/pi_influenza.asp
Gregg
gregg a. miller says:
Hi Gaby,
I’m curious to know where you heard about the cancer/vaccine link. I’ve never heard about this, I looked into it, and couldn’t find any information about any link. In fact, the vaccine is recommended in patients with cancer. As far as I know, there’s no connection between the influenza vaccine and cancer.
Thanks,
Gregg
gregg a. miller says:
Hi Sara,
Look at my article for the answer, third question from the end.
Gregg
gregg a. miller says:
Hi Stefanie,
I understand your concern. In the end, the decision to get this vaccine is a personal one. You have to weigh the known risks of the H1N1 flu which are usually pretty minor, but sometimes deadly, versus the unknown risk of the H1N1 vaccine, which so far appears to be safe but currently there’s no way of knowing any long term side effects. If it reassures you at all, the H1N1 vaccine is manufactured in exactly the same way as the regular flu vaccine, and the regular flu vaccine is extremely safe.
Hope that helps,
Gregg
gregg a. miller says:
Hi Brooke,
Snips and snails and puppy dog…wait, that’s something else. The injectable vaccine is made from the H1N1 virus, which has been inactivated and cut up into little pieces and therefore does not cause infection. The virus has been cultured in eggs, so some egg protein might be present which is why egg-allergic people should not get the vaccine. In some cases, thimerosal is added. Adjuvants are not added to any of the vaccines made in the US. The live nasal spray vaccine contains live, modified virus that cannot cause serious infection. It does not contain thimerosal or adjuvants.
Hope that helps,
Gregg
gregg a. miller says:
Hi Andy,
If someone indeed has had H1N1, then the vaccine won’t provide any additional benefit. However, it’s unlikely that you’ll know for sure that it’s H1N1 and not the regular flu—the test that most doctors do in their office is a rapid flu test that is not extremely accurate, and even when it does detect flu virus, cannot distinguish H1N1 virus from other seasonal flu viruses.
Gregg
gregg a. miller says:
Hi Logan,
I’m glad you’re paying good attention to your health at 13, it’s good to get into healthy habits as a teenager because it’s hard to start as an adult…I’m talking from personal experience here.
Some people do get minor cases of flu-like illnesses from the nasal vaccine, and they have symptoms like the ones you have. Those symptoms are usually short-lived and not nearly as severe as the flu. If they last longer than a couple days or are severe, you should see a doctor—there’s a chance you got infected with the flu or another virus before getting the vaccine, and by the time you got the vaccine it was too late to do any good.
Hope that helps,
Gregg
Kate Johnson, medical journalist says:
A great set of answers to FAQs about the H1N1 vaccine - but as a medical journalist I've written in my blog about how some of the public's dilemma is not based on lack of facts, but lack of trust. Would love your thoughts on this. See "Should I Get the Shot? The H1N1 Vaccine Dilemma" at http://bit.ly/2MuocV on www.katejohnsonmednews.wordpress.com
Maria says:
hi Gregg,
i have heard and read that getting the flu vaccine weakens the immune system and makes you more more prone to getting the flu. is it a Myth or thr truth?
Having said that my younger son who is 3, got his seasonal flu shot and yet got a mild flu. so does that prove what is stated above?
Second question is if and when H1N1 vaccines are available at schools or doc's office, is it recommened by you for my 2 kids (6 and 3 years)
your blog is really helpful and i am sure you will be able to help me with my concerns.
thanks in advance.
gregg a. miller says:
Hi Maria,
It's a myth. The flu shot actually protects you from getting influenza.
There's a lot of confusion about what the flu shot can and can't do. The flu shot can protect you against influenza, which is caused by a specific influenza virus and can sometimes make you very, very sick. It cannot protect you against the common cold, which is caused by hundreds of different viruses that are not influenza. Your son might have had a common cold, and unfortunately the influenza shot won't protect him against that. The flu shot will protect him against influenza, which can be much more serious than the common cold.
I can't provide specific advice for your children, but in general the H1N1 vaccine is recommended for children of that age. You should talk to your health care provider about it--he or she can give you specific advice for your kids.
I hope that helps.
Gregg
Brian says:
How can we be sure there are no long term effects?
Thank you for your advice, greatly appreciated.
Gregg A. Miller says:
Hi Brian,
Good question, and the honest answer is: there's no way to be 100% sure there are no unforeseen long-term side effects from this vaccine, from any other vaccine, or for that matter, from any medical treatment. However, we are 100% sure that the H1N1 virus is a disease that has sickened millions and killed thousands.
It's tough dealing with uncertainty, and there are no absolute answers. The bottom line is, you have to make your own decision whether you want to take a vaccine that, as far as we can tell, is safe, or if you want to take a low but real risk of catching a disease that could kill you.
Sorry I can't give any definite answers, but unfortunately, that's the reality of the situation.
Gregg
Yanet says:
Hi, I just want to know. How long does the H1N1 Vaccine stays in your body, after you get it? Thanks!
Joe says:
My 13-month old daughter had the first (of a two-part) "regular flu" shot about 8 weeks ago, but everytime we are to go back to the pediatrician for the "2nd part" of the regular flu shot, she is sick (she's been getting ear infections and is on antibiotics), so he has not given her the 2nd "regular flu" shot.
However, next week, there is a clinic that is giving the H1N1 flu shot. We signed her up. Is it OK for a 13-month old who has only gotten "one half" of the 2-part regular flu shot 8 weeks ago, to get the H1N1 flu shot (even though she never got the 2nd regular flu shot?)
Thank you.
-Joe