Category Archives: Influenza

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.

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

CDC – Seasonal Influenza Flu – Adverse Events After Receipt of TIV

Update on the 2010-11 annual influenza vaccination season related adverse effects.

Some of the notable highlights include no increase in febrile seizures in children, no increase in post vaccine fever in adults when compared to placebo (the main hesitation to give it in hospitalized patients).

Anaphylaxis or immediate hypersensitivity is estimated to be rare (1.5 case per million doses) No cases of anaphylaxis was reported in the 2010-11 season.

Botton line: adverse events related to trivalent influenza vaccine (TIV) are very rare for all age groups. It is a safe and cost effective means to reduce influenza related morbidity and mortality.

Reference:

CDC – Seasonal Influenza Flu – Adverse Events After Receipt of TIV.

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. http://www.ncbi.nlm.nih.gov/pubmed/20887208.

No increase in Gullain Barre incidence with H1N1 2009 vaccination-says CDC

The preliminary results from the last H1N1 2009 vaccination season are in. So far no excess cases have been reported with the vaccine when compared to previous vaccination years. More people developed Guillain Barre without vaccination than with the vaccine (total numbers). The rate of cases per 100,000 population were slightly greater in those with vaccination than those without vaccination (0.8 per 100,000 persons greater). These results are consistent with the expected safety profile as seen in previous years.

No statistically significant association between GBS and 2009 H1N1 vaccination has been seen

More information on the history of Guillain Barre and vaccinations

Preliminary Results: Surveillance for Guillain-Barr√© Syndrome After Receipt of Influenza A H1N1 2009 Monovalent Vaccine — United States, 2009–2010.

Successful vaccination season at our hospital

We have almost completed data collection from this years influenza vaccination season. participation has been higher among healthcare associates when compared to previous seasons at 68%. Despite the improvements it is still too low to see the true benefit of herd immunity.
The most frequent reason to refuse inoculation is fear of complications. Of the 1900 doses given this year there were only 8 reported complication. Sounds like a lot at first but 7 of these were merely pain at the site of injection, yes we tracked even issues as minor as that. The remaining one felt faint and was taken to the ER only to be released back to work two hours later. No one called in sick in the subsequent weeks related to the vaccination. And there was no Gullian barre either!
Overall a successful vaccination season but hope to do better next year.

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