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-Barré Syndrome After Receipt of Influenza A H1N1 2009 Monovalent Vaccine — United States, 2009–2010.
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.
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.
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.
If there is one good thing that has come out of this flu season then it is the awareness of vaccination. In years past, on the average we have had 45% vaccine coverage for hospital employees. This has been abysmally low to offer any real herd immunity. This year with an aggressive proactive approach with formal lectures and informal face to face discussions with groups of hospital staff discussing the benefits, myths. We have a record >75% seasonal vaccine coverage. Most of the recipients were taking influenza vaccine for the first time. We may actually run out of seasonal vaccine for the first time.
With regards to H1N1, we did start with live attenuated intranasal last week and had a high acceptance rate among those who qualified. Unfortunately many of the motivated staff did not qualify. This week we did receive inactivated injectable vaccine. The acceptance rate for this has been very good. I did need to go on an education round in the hospital and answer more question. But once a few staff members got motivated more and more followed. I think we will have a good coverage for H1N1 too.
Some factors promoting better acceptance may be the larger numbers of 20-49 year olds that are coming to the hospital with moderate to severe viral pneumonia. A few have required intensive care management. The number of patients coming to the ER with influenza like illness (ILI) has seen a sharp spike in the past week. The proportion of ILI that are influenza A positive has gone up from 3-5% in the weeks of Oct 5th and 12th to 18% in the week of Oct 19th.
So far very few complaints about getting vaccinated aside from the minor injection site aches and pains.
There are more cases of influenza like illness this year than expected. Also the number of deaths are higher than expected for this time of year. 69% of the 12,900 samples sent to the reference labs are positive for 2009 H1N1. Remember that most of these samples are from persons ill enough to be hospitalized. This does not report all infected cases as ambulatory persons are not being screened due to overwhelming demand for tests. The vast majority of cases probably do not need hospitalization. Therefore the number of cases of H1N1 likely to be much higher.
Almost all isolates of 2009 H1N1 are showing a good match to the current vaccine. Remember that the virus does tend to have high mutation rate making 100% coverage difficult.
For the most part H1N1 is showing susceptibility to Oseltamivir (Tamiflu).
Total number of pediatric deaths is now 95 cases nation wide for 2009 H1N1.
See the graph showing the unusual spike in outpatient visits for influenza like illness towards the right of the graph.
Remember to get your vaccination.
The New England Journal of Medicine published a study focusing on the safety profile of the H1N1 vaccine.
It was conducted in China where 2200 subjects received a dose of H1N1. 2103 (95.6%) received the second dose. They ranged in age from 3y to 77y the subjects were randomized to either vaccine or placebo. Patients were removed from the study once they achieved an increase in antibody titer of 4x baseline. Which is considered adequate protective levels. Those that did not achieve this level of antibody received a second dose at day 21.
The results did show good efficacy of the vaccine in adults with just a single dose. Children and the elderly did need the second vaccine dose to get the needed antibody level.
One adverse result was seen in the study, it was development of atrial fibrillation in a man who was receiving placebo. There were no serious adverse results in any of the vaccine recipients. Local pain at the injection site was the main complaint.
This is the New England Journal article: A Novel Influenza A (H1N1) Vaccine in Various Age Groups