Q&A addresses H1N1 vaccine

Lori Williams
713-798-4710
loriw@bcm.edu

Dr. Flor Munoz addresses frequently asked questions about the H1N1 vaccine.

Pregnant women

1. Why should pregnant women get the H1N1 vaccine?

Pregnant women are on the very top of the priority list to receive the H1N1 influenza vaccine. The reason is they are at higher risk of complications, hospitalization, and serious pneumonia if they get the flu at the end of the pregnancy.

2. Isn't it dangerous for pregnant women to get vaccines?

The vaccine would not be recommended if it would be a dangerous intervention. It is much safer to receive the vaccine than to have the actual influenza illness. The use of the vaccine is based on the knowledge of using the seasonal flu vaccine. It is always important to keep in mind that the vaccine is made out of a protein. There is no virus in that vaccine, therefore there is no danger for the mother or the baby to acquire influenza from receiving the vaccination. The vaccine has no substances in it other than the influenza protein that you need to develop protection. Therefore, there is also no theoretical concern of any other side effect than what you would expect to see with the seasonal vaccine. So people who are pregnant who get the vaccine can sometimes get a little bit of a sore arm, a little bit of a fever, maybe low grade, (although most adults don't have a fever with influenza vaccine), or have malaise for a day or two. But all of these are very transient, self limited symptoms that we know are very similar to the seasonal influenza.

3. Does the vaccine cover your unborn child?

Yes. If you are pregnant and you receive the vaccine, it is very likely that the protection will be transferred to the baby. The reason I say it is very likely and not definitive, is because there are factors that are involved. The factors include the timing in the pregnancy when you receive the vaccine. The earlier in the pregnancy, the more time that there is to pass that protection to the baby. It also depends on the time of delivery in relation to the time of vaccination. So, if you have received the vaccine and shortly afterwards you have the baby, it is unlikely that the baby will have protection. If you receive it earlier in the pregnancy and don't deliver until later on, it is more likely the baby will have protection.

Because infants under 6 months of age are not able to receive influenza vaccines, the only way really to protect them is to protect their mothers and have the transfer of the antibody from the mother to the baby. It is also important to protect those around the baby so everyone who is with a child under 6 months of age in their home should be vaccinated as well.

4. Can you get the vaccine anytime during pregnancy?

Yes, you can receive the influenza vaccine anytime during the pregnancy.

Vaccine Preparation

1. How was the vaccine developed?

The H1N1 influenza vaccine is basically the same as the seasonal vaccine, except there is a different virus strain used to prepare it. It is a very well established process. A virus that has been identified is grown in eggs, is extracted from the eggs and purified so that only a portion, the part of the virus that makes our immune system develop protection, is extracted and used in the actual vaccine. This is the way the vaccine is prepared every year. It is no different for the H1N1 vaccine.

2. Why are studies needed for the H1N1 vaccine and not for the seasonal flu vaccine?

That is a misunderstanding. Every year vaccines are tested before they are released. The process includes the selection of the strain, the manufacturing of the vaccine, and the assessment and testing of the vaccine to make sure that it has the characteristics that it needs to be released. In addition, it is important to have information with this new strain about how to better use the vaccine. There are some questions that are not answered with the usual process that need to be addressed with specific studies. How is the vaccine able to work in different populations? Does it really make a difference if you use a certain dose or the number of doses that you give, and Is it going be the same effect in adults, children and elderly populations, for example? So this information is what is being studied in separate studies for the H1N1 vaccine.

3. Was the H1N1 vaccine rushed out before all the safety tests?

The fact that manufacturers were able to put out the vaccine in a very quick manner does not mean that the vaccine was rushed out. Normally, it takes several months to have a vaccine out, yet in this case it's going to be shortened to about half of that, mainly to try to reach the demand of the vaccine, to try to have a way to intervene in a situation of a pandemic. The need is what is driving the fact that this is being done in a very short period of time – that does not mean the vaccine skipped the regular regulation process.

Vaccine Use and Safety

1. Is it possible to get the flu from the vaccine?

It is not possible to get the flu from the vaccine. The inactivated vaccine, the one that is given as a shot, does not contain the flu virus. It has only a purified protein that is unable to cause the flu. The live vaccine (nasal mist) has a live activated virus which also has restrictions as to its capacity to cause any illness. So it might look like it, in the sense that you might have a runny nose, sometimes a little bit of a sore throat, sometimes a low-grade fever, but the vaccine itself is not able to cause influenza.

The vaccine strain that is included in the live vaccine (nasal mist) is attenuated; it has no ability to cause disease.

2. If you think you had H1N1 earlier this year, should you still get the vaccine?

There is no specific recommendation as to whether individuals who had H1N1, even if they thought they had it, or were confirmed to have had it, whether they should receive the vaccine. That is because we are still learning about the immunity. Now, chances are that if they have already been infected with H1N1, they would have natural protection, and they would be less likely to have the infection again or have complications from the infection. But again, there is no specific guideline about that. There are experts that would say go ahead and get the vaccine regardless of whether they have had it or not, because it is still a public health intervention. If the vaccine is not available in large amounts, it's possible that the people who have already had it would be less likely to receive it so that the vaccine would be given to those who need it the most.

3. Are there any reported serious side effects?

The reactions that have been reported are similar to those of seasonal vaccine. No serious adverse events or reactions caused by the vaccine have been reported that cause any concern for use of the vaccine by the general public. Information will continue to be reviewed as the vaccine is being used. As larger numbers of people become vaccinated, there will again be safety follow-ups to try to identify any type of serious or severe reaction to the vaccine if there happened to be one.

Infants and Children

1. If most children are getting over H1N1 with mild symptoms, is the vaccine necessary?

This is the same reason why we recommend that everyone get the seasonal flu vaccine every single year. Why should we get the vaccine if most people get mild illness? Indeed it is true that most children and most people who get influenza, either H1N1 or seasonal, are going to have mild symptoms and do well. The problem is not everybody does, and so just like we see some special high-risk populations get sicker and have complications and die from influenza, there is also severe disease that can happen in otherwise healthy people. In a small number of people you can have severe pneumonia and deaths, even if you were completely healthy before. So it's important to keep in mind that we are trying through vaccination to prevent disease in you as an individual, but also in others as well.

2. Is Thimerosal in the vaccine?

Thimerosal is a preservative that is used to prevent contamination of multi-dose vials. So, only those vaccines that are prepared in multi-dose vials might contain Thimerosal. There are manufacturers that are making single dose administration syringes and those do not contain Thimerosal. The live vaccine given intra-nasally does not contain Thimerosal.

A number of studies have been done to address the safety of Thimerosal as a preservative - these studies have demonstrated that there is no association between Thimerosal and serious adverse events such as autism or other neurological conditions.

3. Should children of all ages get vaccinated?

The vaccines are licensed and recommended for children over 6 months of age. That includes anyone from 6 months to 99 years of age. Therefore, children of any age are recommended to receive the vaccine -- especially those children under 5 years of age because they will be susceptible. We recommend all children up to 18 years old be vaccinated against seasonal, and also H1N1 influenza, because they are at higher risk.

Getting the Vaccine

1. How many shots are needed?

At this time, the anticipation is that it will be similar to seasonal vaccine, so that adults, anybody over age 10, can receive one dose of the vaccine. And children under age 9 should receive two doses, because this is the first time they will be receiving the vaccine. This is based on preliminary data. The final study data is still coming and we will have further guidance.

2. Can I get a seasonal flu vaccine at the same time as the H1N1 vaccine?

In general the answer to that question is yes, but it depends on which vaccine you are using. The inactivated vaccines, the ones given as a shot, are expected to work in the same way as regular inactivated vaccine so you can give them together or give them at any time, before or after each other. The difference is with the live vaccine, the intra-nasal live vaccine. Administration of live vaccines requires a 4-week interval between vaccines unless they are given on the same day.

3. Will the H1N1 vaccine protect against the seasonal flu? Do I need both vaccines?

The H1N1 vaccine is a virus that is different from what is in the seasonal influenza vaccine. Each of them has their purpose. The seasonal vaccine is meant to protect against the virus strains that regularly circulate throughout the influenza season, and the H1N1 protects against H1N1 only. Therefore, they have no interaction with each other. If you get the H1N1, you will have protection against H1N1, but not against the other viruses. And vice-versa. The seasonal vaccine is not expected to provide cross-protection against the H1N1. In order to have a broad, good general protection against influenza this year, it is important to receive both the seasonal vaccine and the H1N1 vaccine.

4. How is the vaccine distributed?

The information that is available regarding the distribution of the vaccine comes from the CDC. The vaccine is being prepared by manufacturers, companies that prepare the vaccine independently, and then it is being purchased by the government, and it will be distributed by the government through a central location. The central distributor will be able to send the vaccine to the different states and it will depend on each state's regulation how the vaccine will be distributed within the state.

The H1N1 Virus

1. How long does the H1N1 virus live outside the body?

Influenza viruses are intra-cellular parasites. They live inside cells. Without the cells they cannot survive. Therefore, it is possible that if you have respiratory secretions, people coughing and sneezing and touching a surface, as long as there are cells, the virus can live there. But once that dries up and once the cells die, then there won't be any virus left to cause any infection. So there is a possibility that a virus can be transmitted by touching a surface that has been contaminated. The duration of that is probably in the range of hours, not days or weeks, because the virus is not able to survive past the time that the cells survive outside the body.

2. Who is at most risk for getting the virus?

There is a difference between who is at greater risk of acquiring influenza and who is at greater risk of becoming sicker with influenza. We know that children and young people are at greater risk of catching the flu, of becoming ill with influenza. But they are not necessarily at greater risk of having complications and dying from influenza.

People who are at greater risk are usually people of all ages who can have underlying medical conditions, and we are talking about asthma, heart disease, diabetes, any other type of liver, kidney disease, etc.. Women who are pregnant, also people who are over 65 years of age, even though they are not among the groups that have high risk of getting the H1N1, once they have it, they can have a high risk of complications. And then again, young children, especially those under 2 years of age, can also have a high risk of complications from influenza.

3. Is it true that 50 percent of people in the U.S. will get H1N1?

The numbers that have been put out in speculation on how many people can become infected with the flu H1N1 vary depending on where and what type of community we are talking about. And so, potentially half the population or even more can become infected with the flu because basically 100 percent of the population is susceptible to get it at this point.

The fact that this is a new strain of influenza virus to which most people are susceptible indicates that most people are going to eventually acquire this virus. If they didn't get it during the summer, they will probably get it during the winter. If they didn't get it this year, they will potentially be able to get it or be exposed to it sometime later. This particular virus is one that is establishing itself in the human population and it is expected to continue to circulate through the years. There are probably a lot more people that have acquired H1N1 that we don't know of because they didn't have a serious enough illness, or they were not tested or for many reasons they did not seek any medical attention. But again, the number of people being infected is large, it is very, very large.

Do you have additional questions? Let us hear from you. Although questions can not be answered on an individual basis, they will be included in an upcoming Q&A feature. .