All you need to know about the swine flu vaccine

An orderly but alternately resigned and annoyed crowd lined up outside a Rockville clinic Wednesday seeking to nab some of a limited supply of H1N1 flu vaccinations.
Andrew Pekosz
Associate professor of molecular microbiology and immunology at Johns Hopkins University
Thursday, October 22, 2009; 11:00 AM

Worried about the swine flu vaccine? Andrew Pekosz, an associate professor of molecular microbiology and immunology at Johns Hopkins University's Bloomberg School of Public Health in Baltimore, was online Thursday, Oct. 22 at 11 a.m. ET to answer questions about the H1N1 swine flu vaccine.

A transcript follows.

Read Pekosz's answers to common H1N1 questions and check out our swine flu special report and our list of local swine flu vaccination clinics.


Andrew Pekosz: Hello All, Andy Pekosz here to answer your questions about 2009 H1N1. I'll be here till noon. Let's get started!


Ohio: H1N1 has hit our area of Ohio in the last two weeks - and so far no one in my family has gotten sick. There is a limited quantity of H1N1 Flumist for vaccinations in this area, but the shots aren't available yet. My question is about timing - would it be advisable to vaccinate my 2 and 4-year-olds with Flumist now (knowing it's a weakened, live vaccine and knowing immunity can take at least 2 weeks), or could the vaccine have a negative impact if my kids get H1N1 at roughly the same time through contact at daycare? In other words, would the immune system's response to the live virus make them more susceptible or have a worse case of H1N1 if they're exposed to it at the same time as the weakened virus in the H1N1 vaccine?

Andrew Pekosz: Great question. There are no problems associated with getting vaccinated and infected at around the same time...ideally we would be vaccinating before the infections begin to occur but 2009 H1N1 surprised us with a very early emergence this year. getting vaccinated now will still help reduce the number of cases.


Bethesda, Md.: I was lucky enough to get the H1N1 flumist for my 4.5 yr old twin daughters last week at the Montgomery County clinic. We were told that they would need a booster in 4 weeks. What if we are not able to get the booster because of low supply? Do they still have some protection/immunity? Why do they no longer need a booster for the seasonal flu vaccine but need one for H1N1? Thanks so much for your reply.

Andrew Pekosz: Children under the age of 10 need two doses of vaccine spaced 3-4 weeks apart to get the maximum immune response. One shot should give some protection. Your child is in the high risk group so you should have priority come time for the second dose and more vaccine is being shipped every week so I'm hopeful you won't have an issue getting the second dose. Your kids should also get a second dose of the seasonal flu vaccine to get maximum protection.


Herndon, Va.: Hi Andrew! Can you talk about how much risk H1N1 poses to two particular groups: asthmatics and seniors? I read about the high risk groups, like kids and health care workers, but I'm not clear how much risk there is to these groups.

Andrew Pekosz: Asthmatics have a higher risk of severe disease from both seasonal and 2009 H1N1 influenza. Seniors (over 64 years old) are only in the high risk group for seasonal influenza because there isn't much disease from 2009 H1N1 in that age group. The exception of course, is if you are an asthmatic senior, in which case you at high risk to both seasonal and 2009 H1N1.


Houston, Tex.: I am 26 weeks pregnant and although I will receive the seasonal flu shot, I haven't heard enough to-date about the swine flu vaccine to bolster my confidence about obtaining that version. A friend who is an OB nurse commented that a large portion of the swine flu vaccine is coming from China, as many US manufacturers are not able to meet demands on their own. How can we be sure that quality standards are being met when these drugs are being rushed through so quickly?

Andrew Pekosz: The US flu vaccine supply is not coming from china, it is coming from FDA approved manufacturers in the US and Europe. All the same quality control measures that are in place for seasonal influenza are being applied to 2009 H1N1. the 2009 H1N1 is made exactly the same way as seasonal flu vaccine and there are no known risks associated with vaccinating pregnant women with flu vaccine. Pregnant women seem to get a high amount of severe 2009 H1N1 and seasonal influenza so please consider getting both vaccines.


Reston, Va.: I'm disturbed that yet again there are vaccine production delays which will likely cost lives, given that H1N1 is already widespread and is disproportionally affecting young people. Why is it so difficult for there to be enough vaccine by late October, when this crisis began in April or earlier? Perhaps part of the government's jobs creation plan should be training unemployed workers to produce vaccines, so production can be dramatically increased and fall under the purview of the CDC. In the meantime, we're left with handwashing, sanitizer, and hoping that every sniffle doesn't lead down a scary road.

Andrew Pekosz: The problem with the 2009 H1N1 is that it emerged late in the, it emerged this fall much earlier than expected. both of these factors have made it a difficult year to effectively immunize against influenza.


Washington DC: Hi Mr Pekosz,

I've heard conflicting reports. Previously, I had heard that people who may have had Russian flu in 1978 (or a version of swine flu in 1976, that prompted the hasty production of a vaccine) might have some immunity to the current strain of H1N1.

Now, however in an interview with a doctor on 60 Minutes last Sunday, it was said that anyone born after 1950 wouldn't have immunity.

Can you provide some insight?


Andrew Pekosz: Some of the initial studies suggest people around 60 years of age or older have some immunity to 2009 H1N1, probably because of exposure to H1N1 viruses that circulated when they were young. However, only a portion of that population (30%) has immunity and some of it is low, so if you are in that age group, don't assume you are immune, get the vaccine when its released to the general public.


Arlington, Va.: I got a swine flu shot in 1976 when President Ford told us to get it. Am I still covered?

Andrew Pekosz: The immune response to a flu vaccine only about lasts 9-15 months so the immunity you got from the vaccine is gone.


Washington DC: At what point can we know that our symptoms are becoming much more serious than just the seasonal flu? Do I have to wait for respiratory problems to escalate before we know that it could be swine flu?

Andrew Pekosz: there are two things to consider. first, if you are in the high risk groups for severe H1N1 ( ) then you should consult you healthcare provider as soon as you show symptoms of the flu so you can start antiviral treatment. for the rest of the population, most cases will resolve in 3-5 days with simply staying home, resting and treating your symptoms with over the counter medications. you should only seek treatment if you develop severe symptoms (shortness of breath, lethargy).


DC: My grandfather is an asthmatic senior (88 yrs. old) and he is allergic to eggs which means he cannot receive the flu vaccine (on doctor's orders). Any suggestions for high risk groups who cannot for a variety of reasons receive the vaccine? Every expert I hear says, "get the vaccine" which is not helpful in my grandfather's case.

Andrew Pekosz: If a member of your family or household is in a high risk group that can't get vaccinated, there are a few things you can do. First, get everyone in the household vaccinated which may limit the exposure of the high risk person to influenza. Second, practice good hand and cough hygiene...wash your hands or use sanitizer frequently and have members of the household be very careful about coughing and sneezing into their sleeves or into tissues. finally, if the at risk person does get flu-like symptoms, contact your health care provider and start treatment with Tamiflu...this has been shown to be very effective at preventing serious disease in high risk populations, particularly if started on early after symptoms begin.


Wheaton, Md.: ciao Andrew,

My wife, three kids and I all have the swine flu right now. The doctor's office did a nose culture and we tested positive for a type-A flu virus, which they said is most probably swine flu at this point in time.

Our youngest two children don't seem to be too affected. There is some coughing and a bit of crankiness, and a need for a little more sleep, but not much else. Our oldest boy also had an ear infection, but after the antibiotics kicked in, he also seems fine.

I have a bit of muscle soreness and some congestion, and my wife has the same and is extra tired.

Overall though we don't seem to be affected much by the virus. Is this normal or did we catch a "lesser" strain?

From all the publicity we thought we might end up in the emergency room with a kid or two, but that has not been the case.

I'd appreciate your thoughts.


Wheaton dad

Andrew Pekosz: It sounds like you all had the mild form of the 2009 H1N1, which is what most people get. The severe form of the illness only occurs in a small number of cases, but when it does occur it progresses very quickly and needs to be treated promptly.


Raleigh, NC: Hi Andrew, I'm curious why so many people seem to think the H1N1 vaccine is unsafe. Flu vaccines have been around for a long time. Is there a particular concern about this vaccine, or do people worry about ALL flu vaccines?

Andrew Pekosz: The 2009 H1N1 vaccine does appear to be as safe as the seasonal vaccine. I think some people perceive that the vaccine has been "rushed" into production without proper testing. This isn't the case. it is safe and generates a very strong immune response...there are published data showing this. In addition, many places are monitoring for adverse side effects from the vaccination campaign so we will continue to accumulate safety data throughout the fall. There are other people who feel there is some sort of "conspiracy theory" regarding 2009 H1N1 and the vaccine involving the government/vaccine makers, etc. I can't comment on conspiracy theories, all I can point to is the scientific facts as we know them right now...


Alexandria, Va.: I'm annoyed at a friend who told her child who then told my children that the vaccine was dangerous to children and pregnant women. I feel not getting vaccinated is socially irresponsible. What is your opinion on the proper response?

Andrew Pekosz: This is important...I've answered this before but I'll answer it again because it is important. The vaccine, either the seasonal or 2009 H1N1, is not dangerous to children or pregnant women. The risk of severe disease or death from 2009 H1N1 infection is greater than any risk identified from the vaccine. There are always some number of people who have side or adverse effects from vaccines or any other medical procedure. For influenza vaccines, these are limited to some pain and swelling in the arm you get the injectable vaccine or some sniffles/runny nose symptoms within 2 days of getting the nasal spray.


Severn, Md.: My daughter caught the flu two weeks ago, but the doctors never identified it as either the H1N1 or common flu. The said the common flu has not begun yet. Since she probably had the h1n1, not sure though, should she be vaccinated? Also, is the mercury in flu shots, after say 30 or 40 years accumulation, what is the long term risk of mercury to the nervous system?

Andrew Pekosz: If you haven't been confirmed to have 2009 H1N1 - and most people who have gotten the flu haven't been confirmed - you should get the vaccine. Other, unrelated viruses can cause "flu-like" illnesses so vaccination is still recommended for those who think they have had the flu. The mercury you are referring to is in the thimerosal preservative used in some formulations of the influenza vaccine. This has been studied intensively and there are no short or long term adverse effects of thimerosal after vaccination.


Andrew Pekosz: lots of questions about immunity to influenza after infection. If you have been confirmed to have 2009 H1N1, then you have immunity and won't get infected again this year with that virus. However, most people who get the flu this year won't be tested for 2009 H1N1 (there is not enough capacity in the labs to test millions of people) so most people won't know for sure if they have been infected. If you didn't get a test saying you were positive for 2009 H1N1, don't assume you had it, get the vaccine per the CDC guidelines.


Helena, Mont.: I am allergic to eggs, as well, and never get the flu vaccine but thought I might be able to get the nasal vaccine. Is the virus for it grown in eggs as well?

Andrew Pekosz: The nasal vaccine is also grown in eggs so if you have an egg allergy, you shouldn't get either flu vaccine.


Rockville, Md: Just venting:

I can't find any of the injectable H1N1 around Rockville. My 4-year old son has asthma so is in high-risk and not "eligible" for flumist.


Andrew Pekosz: The injectable form of the vaccine is coming a bit later than the nasal spray form. The manufacturers state that the number of vaccine doses shipped per week will be increasing over the next few weeks so keep checking in with your local public health officials about where the H1N1 vaccination clinics will be, and which will have the injectable vaccine.


Alex., Va.: I have an appointment to get the regular flu shot on the 30th.

How long will I need to wait to get the H1N1 (Hamthrax) vaccine? As a 44yo male with no health problems, should I even be worried about getting the vaccine?

Andrew Pekosz: you can get the injected vaccine in any combination without worrying about a reduced immune response. you can also get one does of the nasal spray vaccine and one dose of the injectable vaccine without having to wait in between vaccinations. The only time you need to wait between vaccinations is if you are taking the nasal spray version of the seasonal and the 2009 H1N1 vaccine...then you should wait about 3 weeks between vaccinations.


Virginia: My doctor is not recommending the vaccine for his senior patients. Are you surprised?

Andrew Pekosz: Seniors are not in the high risk groups for receiving 2009 H1N1 vaccine (unless they have other medical conditions like asthma, etc.) but they are a high risk group for seasonal influenza. Seniors should get their seasonal flu vaccines because while we are seeing mostly 2009 H1N1 infections now, we may see more seasonal flu in December-February.


Andrew Pekosz: Hi All...lots of great questions...I am trying my best to get to a variety of them but apologize if I can't answer all of them.


Totowa, N.J.: I just had my 3 children ages 7, 5 and 2 1/2 vaccinated with the flu shot and also with the swine flu nasal mist. I have been reading about it afterwards and am very nervous now. They still need the second dose of the nasal mist. Are my children safe? I hear we do not know the long term side effects of the vaccine, but I also do not want my children to die from the swine flu itself.

Andrew Pekosz: The nasal spray vaccine is safe in children...there are lots of published data on this. In fact, some studies suggest the nasal spray is a better vaccine in children than the injectable form. My 11 and 7 year olds both got the nasal spray seasonal flu vaccine. All the scientific data says the risk of severe disease from 2009 H1N1 infection is much greater than any risk associated with the vaccine.


Andrew Pekosz: remember everyone...I am not dispensing personal medical advice should always consult your physician for that. I am trying to get across the facts about the vaccine and the infections and hopefully clearing up some of the misconceptions about both.


Tacoma, Wash.: Is there a version of the vaccine for H1N1 being made without mercury? I understand mercury can be harmful to my pregnant wife with twins.

Thank you.

Andrew Pekosz: There are versions of the 2009 H1N1 vaccine that do not contain thimerosal. you'll have to check at the vaccination clinic to see if they are available. There is no known risk associated with thimerosal containing flu vaccines so this shouldn't affect you decision to be vaccinated.


Anondale, Va.: As a healthy middle age person, is it more critical right now to get the seasonal flu vaccine or the H1N1 vaccine(s)?

Andrew Pekosz: You can get the seasonal vaccine now. it will be a few weeks before all the high risk groups are immunized against 2009 H1N1. After that, you can get the 2009 H1N1 vaccine.


Redmond, Wash.: Good morning. Earlier, you said that immunity from a flu vaccine lasts only around 9 months. Is this because of frequent mutation of most flu viruses? And does this mean that vaccine for this year's H1N1 will be good only for this year? Thus far, it seems researchers have detected no mutation of that virus.


Andrew Pekosz: The vaccines, particularly the injectable vaccine, only gives immunity that lasts through the coming flu season. the seasonal flu vaccine changes from year to year because we try to match the vaccine with the circulating virus strains. yes, flu viruses can change from year to year so the CDC and WHO are constantly tracking flu virus strains to pick the best vaccine candidates.


Michigan: Will getting the shot cause autism in my child? I am 28 weeks.

Andrew Pekosz: No...there is no link between influenza vaccines and autism.


Andrew Pekosz: That will wrap up this session. Thanks very much for all the questions and apologies for not answering all of them. Best regards, Andy


Editor's Note: moderators retain editorial control over Discussions and choose the most relevant questions for guests and hosts; guests and hosts can decline to answer questions. is not responsible for any content posted by third parties.

© 2009 The Washington Post Company