CDC releases H1N1 2009 Monovalent safety data

The Centers for disease control (CDC) released safety data on the current season H1N1 monovalent vaccine. Based on data collected a total of 82 adverse events were reported per million doses. This is in comparison to 47 cases per million doses seen in the seasonal influenza vaccine. At first this may seem much higher but the proportion of serious adverse effects was about the same.

Of the 3,783 adverse events reported in the 438,376 doses monitored, 204 adverse effects were categorized as serious (ending in death, hospitalization, disability) similarly 283 serious events were reported for seasonal influenza vaccination.

Of the 13 deaths that were reported nine had underlying illneses. One death occurred after a motor vehicle accident. There were no common conditions or causes of death in the 13 deaths.

With regards to Guillain Barre there were a total of twelve possible cases were reported. Of these only 4 actually met the definition of Guillain Barre.

Overall the number of adverse effects appear to be few and most of them of minor consequences. This is similar to the data published in the New England Journal of Medicine earlier. There are of course limitations in the data especially not being able to detect very rare associations but they will be after all “very rare”.

The healthcare community especially has done a remarkable job with H1N1 given the short time available to mount a response to the impending threat.

source MMWR

An interesting article on mandatory health care worker vaccination

This weeks issue of the New England Journal of Medicine published and article on mandatory health care worker vaccination.

Increasing health care vaccination rates for influenza above the dismal 40% that is usually seen would help decrease transmission of influenza in health care facilities from health care worker to patient. Many of whom are too susceptible to complication of influenza. Vaccinating the health care worker is primarily to protect the patients more than the health care worker. As a bonus it has also been shown to keep health care worker absenteeism down during high hospital census months.

Though I think it is in principle a good idea. I was unsure of the constitutional and legal implications of this. This article does a good job at presenting the legal aspect of this issue. Mainly citing courts upholding vaccination where the public health safety takes precedence over personal preferences.

A few hospitals in Illinois have already instituted mandatory vaccination successfully. This may become the norm in future seasons.

Mandatory Vaccination of health care workers

What about the risk of Guillain barre syndrome?

What Gullian barre? Guillain barre sydrome is a neurologic condition where the body immune systems antibodies misrecognizes parts of the nervous system as foreign and attacks it. The host can develop muscle weakness and even paralysis. This can be a serious condition. Fortunately it is very rare. This is NOT caused directly by a vaccine but by the immune system itself. This can therefore happen with anything that stimulates the immune system to produce more antibodies. In other words infection itself can produce GBS. Most GBS is caused by viral infections and by a common bacteria that causes food poisoning called Campylobacter.

There are about 10-20 cases of GBS per million population in any given year, this is known as the “background rate” of occurrence. This has been closely watched since the initial cases of GBS were reported in the 1970s and does not appear to have changed that much with subsequent influenza seasons. (Roper AH. The Guillain barre syndrome. N Engl J Med 1992 326:1130-6)

The first series of GBS related to vaccination was reported in JAMA in 1980. This was based on data collected from the 1976 influenza vaccination season where it was believed that people were getting GBS from the vaccination. In this study they cite an attributable risk of 13 cases of GBS per 100,000 population vaccinated (an alarmingly high number) based on a collection of 32 cases with a history of vaccination. They needed a background rate for comparison. Due to the lack of public health records for GBS at that time they called local neurologists on the roster of the local medical associations in the state of Ohio and asked them about all the cases they had seen in the studied time interval. With this information they arrived at a background prevalence of 2.6 cases per 100,000. Of course this data was met with appropriate alarm, it turned out to be a public relations fiasco.

More detailed studies of the initial finding were later published regarding the 1976 swine flu vaccination where 40 million people were vaccinated and possible 532 cases of Guillian Barre were reported and 32 people died. This gives a rate of
about 13 cases per million. One tenth the number originally cited in the smaller study and a number more in the middle of the expected background rate. Definitely less alarming.

Data collected prospectively in subsequent years have failed to demonstrate any increased risk.

The risk from vaccination therefore may add an additional risk of perhaps up to 1 additional case per 1,000,000 administered doses of influenza vaccine this is a very small number compared with the original 130 cases per 1,000,000 that was reported in the 1980 article. This is rare enough to go so far as to say that there is probably no causal relationship influenza vaccination and GBS.

How fast does the vaccine work?

“I got sick the day after I got vaccinated, the vaccine does not work!” is a common statement of alarm that frequently comes to me. Please understand that this is neither a failure of the vaccine nor caused be the vaccination itself.

Remember that the vaccine itself does not kill influenza. The vaccine stimulates your immune system to be ready for influenza if it were to encounter it in the future. This preparation or training takes about 2 to 4 weeks. Therefore there is some potential to get the “real” illness early after vaccination, though even that should be milder than if one was not vaccinated.

So if someone at home gets ill in the days after you got your vaccination, do not blame the vaccine. We are in the depths of flu season it is more likely than not that little johnny got infected at school than from your dead vaccination.

Did I get vaccinated?

I did get my H1N1 2009 live attenuated intranasal vaccination on 10/22/09. It was really no big deal, took less than 5 minutes to do. I feel fine today.
I also took the inactivated injectable seasonal vaccination on 10/14/2009. I also vaccinated my family with the same formulation that night. Aside from some arm soreness that my 9 year old complained of, no one has had any complaints.

2009 H1N1 vaccination- the low down

This is a summary of the CDC recommendation on H1N1 vaccination this year, I have added information to add some context to some of the recomendations.

Who should receive the 2009 H1N1 vaccination?

The goals of vaccination are to protect those at most risk of complications from disease, those who cannot be safely vaccinated and those who are at greatest risk of being a transmitter to other susceptible persons.

The groups that should be vaccinated therefore are:

1. Pregnant women – they have been seen to have higher rates of hospitalization and death. This group should only receive the inactivated injectable vaccine.

2. People who live with or take care of children younger than 6 months of age, as these young children are under the recommended age for vaccination and need a protective wall of immunized people around them. Remember the virus needs to spread from an infected person to be transmitted to a non-infected person. Therefore the best way to protect the very young is to only let immunized persons be in contact with them. These persons can receive live intranasal vaccine as long as they are healthy, not pregnant, and under the age of 50 years. All others will receive inactivated injectable vaccination.

3. Healthcare and emergency workers, this is not just to protect them but more importantly to protect their patients. Hospitals and clinics obviously attract patients with H1N1. Healthcare personell will have significant contact with them and if themselves become infected will transmit infection to their colleagues and more importantly other patients that they care for. Vaccinating all healthcare personell will significantly reduce transmission. Remember transmission starts about a day before the fever starts. Therefore damage may have already been done the day before you even get ill. Healthcare workers CAN receive either live or inactivated as long as they are under 50 years of age and are not pregnant and are not involved with bone marrow transplant units.

4. Persons between ages 6 months and 24 years- this group was over represented in the recent ICU admissions and deaths. This group can receive either live or inactivated vaccine as long as they are not pregnant and are healthy.

5. People ages 25-64 with chronic health issues. They will need inactivated vaccination.

Notice that the over 65 age group that is commonly vaccinated for seasonal influenza is NOT on the list.

What if there are shortages of vaccine? The groups that should be vaccinated first are pregnant women, those who live with or care for children under the age of 6 months, healthcare personnel with direct patient contact, children 6 months to 4 yrs and children 5 through 18 years with chronic medical conditions. Once these high risk groups are vaccinated then focus will be on persons ages 25-64 years.

Doses
For those ages 10 and above should receive one dose. Whereas children 9 years and under should receive two doses separated by a month. This is due to the lower immune response with a single dose to have adequate antibodies.

List of those NOT receiving live intranasal vaccine for H1N1
• People younger than 2 years of age; insufficient testing
• Pregnant women; insufficient testing in this group
• People 50 years of age and older; insufficient testing in this group
• People with a medical condition that places them at higher risk for complications from influenza, including those with chronic heart or lung disease, such as asthma or reactive airways disease; people with medical conditions such as diabetes or kidney failure; or people with illnesses that weaken the immune system, or who take medications that can weaken the immune system;
• Children younger than 5 years old with a history of recurrent wheezing;
• Children or adolescents receiving aspirin therapy;
• People who have had Guillain-Barré syndrome (GBS), a rare disorder of the nervous system, within 6 weeks of getting a flu vaccine, though this has never been shown to be causally related any more than getting the “wild type” infection, it is recommended as a precaution.
• People who have a severe allergy to chicken eggs or who are allergic to any of the nasal spray vaccine components. The vaccine including the live form is made with chicken eggs. Remember SEVERE allergy to eggs is the contraindication. Most individuals can take the vaccine if they can eat scrambled eggs or have cake made with eggs.

Regarding seasonal vaccination
It is still necessary for the usual groups– ages over 65 etc
It will not provide protection against H1N1
the list of individuals needing vaccination for seasonal influenza is as follows
Children aged 6 months up to their 19th birthday
Pregnant women
People 50 years of age and older
People of any age with certain chronic medical conditions
People who live in nursing homes and other long-term care facilities
Health care workers
Household contacts of persons at high risk for complications from the flu
Household contacts and out of home caregivers of children less than 6 months of age (these children are too young to be vaccinated)
Note that there is considerable overlap between the seasonal and H1N1 list, many persons will need both vaccinations.

Can seasonal vaccine and H1N1 be given together?
Inactivated seasonal (TIV) and inactivated H1N1 along with pneumovax can be given together.
Live seasonal (LAIV) and inactivated H1N1 can be given together.
TIV and live H1N1 can be given together.
Do NOT give live intranasal seasonal (typo corrected: this was previously written as TIV) and live intranasal H1N1 together

What if I already had the flu this year?
Regardless of whether the illness was H1N1 or not, if you are in a risk group that should be vaccinated do get immunized.

Breast feeding and vaccination?
It is safe, including the live intranasal vaccination.

What about Tamiflu and vaccination?
Do not take Tamiflu for 2 weeks after live intranasal vaccine, it will kill the vaccine virus.
Do not get vaccinated for at least 48 hours after Tamiflu is discontinued.
Inactivated injectable vaccine can be given with Tamiflu.

Varicella Zoster vaccination

The topic of varicella zoster vaccination has come up several times this week. Probably time for a summary.

Varicella zoster, commonly called shingles is caused by the reactivation (reawakening) of chickenpox virus also called varicella zoster virus (VZV) in the distribution of a nerve root that results in a localized single-sided rash that later blisters (vesicles). The rash itself is not the problem, the pain that occurs due to nerve damage called post herpetic neuralgia can be. Post herpetic neuralgia can be very difficult to manage. This can therefore be very debilitating in the sufferer. The idea of vaccination with the shingles vaccine is to prevent or at least minimize the pain and suffering that goes along with shingles.

One does not acquire shingles from another patient with shingles. As mentioned above. Shingles is the reawakening of the chickenpox that occurred many years ago. In other words the bugs causing shingles are your own. One cannot get shingles from shingles either. But one can get chickenpox from a case of shingles.

Prior to the introduction of chickenpox vaccination, 95.5% of people 20-29 yrs of age and more than 99.6% of people 40 years of age or greater have evidence of previous chickenpox (VZV) infection. All of these persons are at risk of later developing shingles. Once one has recovered from chickenpox the virus does not leave the body. It can remain contained in parts of the nervous tissue called doral nerve root ganglia. As long as our immune system is healthy, the virus remains dormant and contained. However, if our immune system is no longer capable of watching over these prisoners, they can reawaken and lead to shingles. And through that considerable pain and suffering. Shingles develops in about 30% of people over their lifetime. The likelihood of shingles rises with every decade of life over 50. By the time we are in our 80s one in two persons may suffer from shingles. This correlates with the gradual decline in antibodies to varicella. Therefore adequate boosting of anti-varicella antibodies should help reduce the incidence of varicella reactivation.

The varicella vaccine for chickenpox is very effective in preventing primary or initial infection with varicella in children and has become part of the standard vaccination schedule. It is a live attenuated (weakened) vaccine. However when this same vaccine was used in older adults it was found to not stimulate the immune response enough to prevent shingles. Hence the zoster preparation of the vaccine though containing the same weakened live varicella virus is in 14x greater quantity that was found necessary to bring antibody response to protective levels.

Trials from zoster vaccination appear to result in a 51% reduction in the incidence of zoster with a 67% reduction in the incidence of post-herpetic neuralgia (the pain). Those that did have pain despite being vaccinated wen compared to non vaccinated did so for 21 days on average compared to 24 days respectively. The severity of pain was also less in the vaccinated group.

The vaccine is currently indicated in adults aged 60 or over and are not receiving any immunosuppressive therapy such as steroids, chemotherapy. This is a currently recommended as a one time vaccination. This is not to be used to treat active shingles or the pain from recent shingles. Some experts do recommend vaccinating persons with zoster vaccine 12 months after recovering from an episode of zoster.

Most common side effects include pain at the site of injection and occasionally vesicles can develop. No cases of transmission of live virus to other individuals has been seen.

Why do we need to be vaccinated against influenza every year when other diseases do not?- updated 10/23/09

There are two basic kinds of viruses, those that are made of DNA, the stuff we are made of and RNA viruses. These are viruses that contain a more primitive form of genes.

DNA tends to more stable and reliable from generation to generation. Hepatitis B and Small Pox are examples of DNA viruses.

Influenza on the other hand is an RNA virus and a very unstable RNA virus when compared to other RNA viruses. When it invades a host cell it creates million of copies of itself. In the process it kills the host cell. But because RNA virus have poor error checking due to the lack of a proofreading enzyme called DNA polymerase the copies of itself are very sloppy. Over 80% of these copies are unusable and are not infectious. The remaining ones are infectious to other cells but are still not exact copies of the mother virus. They are therefore “quasi-species” that is; they are very similar but not exact. Over time the virus gradually changes in its genetic makeup.

Our immune system recognizes an invader as alien by its genetics. The specific site on the virus that our antibodies recognize is called the “epitope”. If the genetics of the virus change too much i.e. change the epitope then our immune system takes longer to get into action, sometimes too late. If our immune system has been primed to recognize the viruses epitope from recent experience like a vaccination which is exposing that epitope to our antibody factory. This is akin to getting the floor plans. Then our immune system will shift into high gear much quicker because of the headstart. Hence the need for revaccination every year with a virus that is as close to the current strain as possible.

Plus the antibodies that we do make do not stay around in ample supply forever. In the case on Influenza the antibodies last about 4-5 months. This is also why the sickest people should not get vaccinated too soon before the season. After october 1st is generally a good time to get vaccinated that way we can face the influenza season with the optimal quality and quantity of antibodies.