Category Archives: TIV (flu)

Trivalent influenza vaccination

Side effects of Influenza vaccination

As we head into another influenza season we are trying to improve our hospital staff vaccination rates. The goal of vaccinating hospital staff is two fold. First to keep the staff from getting influenza themselves and second by keeping the staff from getting ill they do not become involuntary spreaders of disease to hospitalized patients. Thereby protecting the chronically ill patients at the hospital. The second reason described is often forgotten and overlooked. I cannot begin to count the number of times I have been told that they do not need a flu shot because they don’t sick from the “flu”.

Remember it is more about protecting patients, the weak and infirm who may not have the ability to tolerate a respiratory tract infection

After that discussion the next heard is concerns over vaccinating patients and how the vaccine can or will make them ill. Often cited is a concern that a post vaccination fever is not discern able from a post op fever. Archives of Internal Medicine published this study in 1996 by Nichol et al. The study, a randomized placebo controlled prospective trial looked at the number of symptoms including minor ones such as injection site pain and fever post vaccination compared to placebo. Their findings include that fever post vaccination is no more common than placebo.

JAMA Network | Archives of Internal Medicine | Side Effects Associated With Influenza Vaccination in Healthy Working AdultsA Randomized, Placebo-Controlled Trial.

An excellent review on the future developments of influenza vaccines

This review was published in the Nov 18th, 2010 issue of the New England Journal of Medicine. It does a great job detailing the vaccine production and some of the pitfalls in developing newer universal vaccines; influenza vaccines that do not require annual shots. It is a must read.

Seasonal Influenza Flu – How often do side effects occur?

Lately I have been approached several times about the incidence of fever post vaccination. Data suggests that it is a rare and benign issue at best. In a placebo controlled trials it was no more frequent than in the control group.

Placebo-controlled trials demonstrated that among older persons and healthy young adults, administration of TIV is not associated with higher rates for systemic symptoms

Therefore the presence of low grade fever or the concern for fever should not be a contraindication for vaccination.

Also of interest is the recurring concern for Guillian-barre. In this series there were no cases in over 4 million doses administered.

This is link to the 2010-11 summary of the reported adverse reactions to influenza vaccination.

Influenza vaccination reduces MI and stroke in elderly- a published study

Just another reason to have the elderly vaccinated every year with Influenza vaccine along with appropriate 23-valent pneumococcal vaccine (when is pneumovax given?).

This prospective study in Hong Kong observed readmission rates among 36,000 elderly patients. The study found statistically significant decrease in the number of deaths, pneumonia, strokes and myocardial infarctions among the studied population.

One may ask “What does a vaccine have to do with prevention of stroke or MI?”. The reasons are that this population is at risk for these stressful infections. The burden of these conditions (sepsis) can further stress a compromised elderly patient and can “push” them into a stroke or and MI. These vaccine may not even completely prevent the illnesses themselves but by reducing the stress of the illness can go a long way in reducing morbidity and mortality from other conditions such as MI and strokes.

Also of note that very few if any “side effects” that are often cited in the lay media were seen. If there were more side effects it should have been seen in the higher hospitalization rate. In fact the vaccinated group had lower death and hospitalization rates.

For more information read the reference:

1. Hung, Ivan F N, Angela Y M Leung, Daniel W S Chu, Doris Leung, Terence Cheung, Chi-Kuen Chan, Cindy L K Lam, et al. 2010. Prevention of acute myocardial infarction and stroke among elderly persons by dual pneumococcal and influenza vaccination: a prospective cohort study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 51, no. 9 (November): 1007-16. doi:10.1086/656587.

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.

Pregnancy and H1N1 vaccination

The question of vaccination for Influenza (H1N1) in pregnancy is frequently asked. A small study published by NIH does provide some answers around this.

Why all the concern about pregnancy?
To date there have been 100 pregnant women hospitalized with H1N1 in the US this season. 28 deaths have occurred in this group. This is an alarmingly high proportion for this healthy group (28% of admissions!). Though the total numbers seem very small it is the proportion of deaths in this important group that is high. Why is this group more important than other? To say the obvious; too many other lives depend on these women. A pregnant women is likely to have other children at home, those children are not only at risk for illness from mother but if mother is incapacitated or worse dies can changes the social structure of the home and future lives of her young children. Loss of life in other groups of people as traumatic as it may be does not carry as great a social burden as losses in this group can. This group is therefore at highest priority to be vaccinated.

Do pregnant women have adequate response to vaccination?
The study does show that pregnant women do mount an adequate response to a single dose of inactivated injectable vaccine and it is well tolerated. The 15mcgm dose appears to provide adequate response in 92% of recipients and 30mcgm in 96% of recipients. the pool sizes were very small at 25 women in each group.

The H1N1 2009 vaccine is made in an identical process to the existing seasonal influenza vaccine. It is a killed vaccine, therefore cannot cause H1N1. It is also thiomersal free.

Does vaccinating for influenza on a large scale offer any advantages?

In this day of rising health care costs it is reasonable to ask the question if mass immunization costs are worth it? It may be worth it if it only decreases the number of deaths and hospitalizations from influenza related illnesses. Some benefit appears to be from vaccinating on a community level to create herd immunity.

So what is herd immunity? Think of a group of persons in a large room. If a virus is introduced into the room it can infect the first person, multiply, infect say 3 more, multiply these 3 will infect 9 more, and so on. However if some of the persons in the room are immune to the virus then it cannot multiply in that immune individual. If more and more persons are immune in that room then it becomes very difficult for viruses to spread as it runs out of susceptible persons. If enough persons in a group are immune then the few persons with less immunity like the elderly really start to benefit from the immunity of the herd.

An estimate of this was made by Weycker et al they estimated that a 20% vaccination rate among children would decrease the number of influenza cases by 46% and an 80% coverage would be needed to decrease the disease by 91%. This is a significant finding. This can be done, as has been proven in the case of small pox where high levels of vaccination literally cornered the virus until it had no one to infect. As of december 1979 there are no human cases of small pox.

In Ontario Canada Jeffery Kwong et al did show improvement in hospitalization, emergency room visits for pneumonia and influenza like illnesses. This study was undertaken after Ontario decided to provide free influenza vaccination to all of its citizens in 2000. The study was conducted on data collected from all hospitalizations and ER visit for pneumonia and influenza like illnesses between the years 1997 and 2004. Vaccination rates increased to 38% of population from the pre 2000 rates of about 18% coverage. The data was compared to other Canadian provinces with similar population sized in the same year which had 24% vaccination coverage rates. During this time hospitalizations and deaths from influenza related illnesses decreased throughout Canada but the decrease was more pronounced in Ontario. Ontario saw 74% reduction in influenza related deaths compared with a 57% reduction in other provinces. In this study the rate of hospitalizations and ER visits was 40% less in Ontario than in other provinces. The group that saw the greatest benefit from vaccination with reference to ER visits, hospitalization and physician ER visits were the 50-64 yr age group they saw up to 80% less healthcare visits. The difference becomes much less obvious as we look at older groups that probably have other medical problems and respond less favorably to vaccination. Notably no significant increase in side effects or Guillian barre were seen in Ontario.

The societal cost savings can also be measured in terms of days lost at work, child care etc. This was shown in a study done by Bridges et al. That showed that even in years where there is a poor match between circulating virus and vaccine a net societal cost of $65.59 per person was seen in terms of lost wages compared with no vaccination. Whereas in years that a close match is seen a net societal cost of $11.17 per person is seen. These are very small prices to pay for improvement in healthcare cost.

In conclusion, there are reductions in healthcare costs with adequate vaccination though this is not seen at the individual level especially when community vaccination rates are low.

Differences between intranasal live and inactivated injectable vaccine for influenza H1N1

Both vaccines are effective. They are manufactured with similar ingredients and both have chicken eggs in them.

Live intranasal vaccine
1. At least in children appears to provide 30-50% greater immune response.
2. Easy to administer- no needles
3. No evidence that transmission of live virus to contacts occurs. Still would recommend precautions if taking care of patient with recent bone marrow transplant.
4. Not approved for 49 years or pregnancy
5. Should be avoided if taking other live vaccines such as MMR, shingles vaccine at the same time
6. Inactivated vaccines can be given with it, such as seasonal influenza
7. Should avoid Tamiflu for 48 hours before and 2 weeks after vaccine

Inactivated injectable vaccine
1. Lower response rate
2. Needs injections
3. Better safety data in the over 49yrs and in pregnancy
4. Can be given ages 6 months and up
5. Can be given with other vaccines
6. Can be given to very immunocompromised patients
7. Tamiflu does not interfere with it