Category Archives: Influenza

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

Influenza cases finally dropping- an update

The past few weeks are finally beginning to show a declining trend in the number of cases with influenza like illness (ILI) presenting to the ER . The last wave appears to have peaked the week of Oct 12-18 when we saw about 17% of visits to the ER having an ILI. The week of Nov 9-15 had 6% of visits with ILI. This week may be even lower. This is a welcome relief from the peak levels of mid Oct.

Nationally the same declining trend appears to be taking place with fewer states reporting active H1N1.

Does this mean that the season is over or that vaccination is not necessary? The answer is no to both.

Influenza does come in “waves”. We had a wave over spring break and another in Oct. We may get another wave in the next month or so. Having enough herd immunity through vaccination can minimize the wave by decreasing the number of susceptible individuals in the community. Remember the vaccination is of greater benefit for the community than for the individual. We all go a long way in protecting those who cannot protect themselves. So those who have not gotten their vaccinations should still do so.

On a side note; We are continuing to have intensive care hospitalizations due to influenza related complications. This week we have two otherwise healthy individuals between the ages of 45-50 with severe pneumonia related complication in the ICU. Both cases have been ill for over a month before seeking medical help. Both would have been infected during the last wave of influenza. Neither of them were vaccinated.

Remember even though the wave may have past. There are still people that may still be suffering from delayed complications.

Influenza activity Aug 30 to Oct 31 2009- a summary

Updates from the CDC show.

1. H1N1-2009 is the dominant influenza in circulation
2. Most isolates appear to be sensitive to Oseltamivir (tamiflu)
3. Outpatient visits for influenza like illnesses is higher than expected for this time of year (7.7% instead of 2.3%)
4. 672 deaths occurred due to lab confirmed H1N1 related illness in this time frame.

What is the effectiveness of seasonal influenza vaccination in preventing H1N1?

Data published from the CDC suggests that the seasonal vaccine is about 10% effective against H1N1, further underlining the need for specific 2009-H1N1 specific vaccination for this season.

In our local community the public response to vaccine clinics has been very good. We hope to increase the vaccination rate as the supply of vaccine improves in the coming week.

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.