Posted on 10/14/2009 11:06:52 PM PDT by neverdem
As U.S. health care providers await delivery of the first doses of vaccine against pandemic influenza A(H1N1), researchers are finding that some patients with the infection shed live virus a few days longer than commonly occurs with seasonal flu, according to a Canadian study with 100 patients.
The public health implications of the finding aren't clear, Dr. Gaston De Serres said during a press briefing at the annual meeting of the Interscience Conference on Antimicrobial Agents and Chemotherapy.
The results show that it's not enough to isolate people infected with pandemic H1N1 flu for just a couple of days after they become sick or until their fever resolves. People “may be tempted to reduce their time at home [when infected by H1N1], but our results show that would not be wise,” said Dr. De Serres, a medical epidemiologist at the National Public Health Institute of Quebec.
The study focused on 43 patients with symptomatic flu who were culture positive for the pandemic virus. In this group, eight (19%) remained culture positive 8 days after their symptom onset. In contrast, all patients with seasonal flu are routinely culture negative a week after symptom onset. “We can say that H1N1 appears to be shed longer [than seasonal flu] but not much longer,” said Dr. De Serres, who also is professor of epidemiology at Laval University, Quebec. All 43 H1N1 patients in the study were culture negative 10 days after symptom onset.
Another 57 family members of these cases had concurrent flulike symptoms, but all 57 were culture negative the first time they were tested. Adding these 57 to the first 43 produced a total of 100 patients apparently infected with H1N1, of whom 8 were culture positive a week after their illness began, establishing a minimum 8% rate for the persistence of H1N1 shedding beyond a week of infection. The rate might even be a bit greater because all of the family members may not have been infected with H1N1.
Dr. De Serres cautioned that the findings don't mean that all eight patients remained contagious at day 8. Contagion requires more than just shedding live virus; it also requires transmission of an adequate virus dose. The study didn't look at the amount of virus shed on day 8. People who shed live virus “may potentially be contagious; we're not saying they are contagious,” Dr. De Serres said.
Vaccine against pandemic influenza A(H1N1) were on track to reach providers early this month, a Centers for Disease Control and Prevention official said at a meeting of the National Vaccine Advisory Committee.
This timetable applies to the vaccines that received approval from the Food and Drug Administration last month, said Dr. Jay Butler, who heads the H1N1 vaccine implementation program for the CDC in Atlanta. (See related stories on p. 5).
The U.S. government has arranged to purchase 194 million H1N1 vaccine doses, which will be supplied to the U.S. public at no charge for the vaccine (although there will be charges for ancillary materials), said Dr. Robin Robinson from the Biomedical Advanced Research and Development Authority of the Department of Health and Human Services in Washington.
Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, said that during the first 2 weeks of September, 4% of visits to CDC sentinel providers of outpatient or emergency department care were for flu-like illness. That rate is as high as that seen in February 2009, the most recent peak of seasonal influenza in the United States. At press time, the spike of flu cases had been most dramatic in states located in the southeastern United States.
Dr. Schuchat's data also showed that U.S. cases of H1N1 infection never disappeared over the summer, although the reported cases of flu-like illness were down compared with the prior H1N1 peak last April and May. Current assessment of the virus indicates that the strain circulating in early September is not genetically different or any more virulent than the strain that circulated last spring.
Based on recent data on immunogenicity, the new H1N1 vaccine will be administered to people aged 10 and older as a single dose. Children younger than 10 are slated to receive two doses regardless of their immunization history.
Other notable features of the H1N1 infection pattern have been higher than usual infection rates in people aged 5-17 and 18-49, and the unexpected finding that morbidly obese people were among those at increased risk for infection. The highest hospitalization rates for H1N1 infections have been in patients younger than 5, followed by those aged 5-24.
The threat of H1N1 infection in young adults aged 18-24 has created a new target for immunization messages, said Dr. Kris Sheedy, communications director for the CDC's National Center for Immunization and Respiratory Diseases.
Until safety data from broad field use are available, the CDC will need to rely on the fact that the new H1N1 vaccines were made by the same methods that have been applied in past years to produce hundreds of millions of doses of seasonal flu vaccine, Dr. Schuchat said. This record of safety should be balanced against the clear health risk that H1N1 presents, a comparison that should convince most people to get immunized.
Surprised it took this long to notice.
While I'm not sure the panic, or the anti-panic is justified, it is encouraging to learn that modern day vaccine technology can isolate the virus and engineer a vaccine and replicate that vaccine in sufficient quantities, so quickly.
That's a good point - and I just got through remarking how impressive it's been that they've manufactured so much vaccine, so quickly. To a laymen, you would think one of the first things you'd want to establish - from a public health perspective - is how long the infected stay contagious.
If this particular virus leaves the infected infectious longer than most other flu virus, it would go a long way to explaining why this particular strain appears to be more virulent.
micro ping
No. Don’t take the vaccine at all.
What's that supposed to mean?
It would most likely cause Guillain-Barré syndrome, a debilitating nervous system disorder.
So how long do people who take the nasal spray vaccine shed viruses?
I thought the nasal spray was dead virus, so your body would only produce antibodies. Limited quantities available.
The injected vaccine is live virus and this is why people with compromised immune systems should no take the shot.
Back in the spring they were saying that the kids were shedding the virus longer than normal. That was why they were being told to stay home 10 days and some schools closed for 2 weeks at a time.
I think you are correct. I forgot about that.
It’s the other way around. The FluMist (nasal spray) is a live weakened virus, and the shot is an inactivated virus. Those who are immunocompromised (such as myself) ONLY can get the shot.
I suspect I’m shedding like a junk-yard dog with mange...
It is not pleasant stuff.
Oh, so now I need to ask the question again. How long (if at all) do nasal spray folks shed the virus?
That is not something that has been established, according to this document from the American Society of Health-System Pharmacists (page 3 of 4). http://www.ashp.org/DocLibrary/Policy/Influenza/influenzalive_ahfs.pdf
“Vaccine virus capable of infection and replication is present in nasal secretions of vaccine recipients, and viral shedding occurs in adults and children who have received the intranasal live vaccine. Relationship between vaccine virus replication in vaccine recipients and transmission of vaccine virus to other individuals not established. However, transmission of vaccine virus has occurred rarely between vaccine recipients and their contacts. Duration of vaccine virus replication and shedding in vaccine recipients not established”.
Having said that, keep in mind that FluMist is a WEAKENED virus that will not cause infection in a healthy individual, but is enough to produce an immune response. From what I gather though, it seems that it is not as effective as the “shot”. http://www.flumist.com/Professional/Efficacy/Vaccine-Efficacy-Children.aspx
I have a horse in this race, as I’m a transplant recipient AND a health care professional. My transplant surgeon told me I should not be around those who have received the nasal vaccine, and this seems to be common across the country as far as advice from transplant centers. Having had the transplant, I have noticed that transplant professionals tend to be overly cautious (a desireable trait) in regards to their patients.
I did discuss this with 2 Infectious Disease specialists that I work with, and both said it is not an issue, except for those with severe immune suppression such as patients who have undergone recent bone marrow transplant (aka stem cell transplant). The one ID specialist worked at a top transplant facility (ranked in top 5 in the world), and initially they were advising this, but have since changed their opinion, and do not feel that this is a threat. Having had the transplant, I have noticed that transplant professionals tend to be overly cautious (a desireable trait) in regards to their patients.
I’m a RN at a large medical center; I mostly work in an outpatient clinic, but also work in the hospital several times per month doing direct patient care.
As for myself, I have told my manager that I will not administer the vaccine, but realistically, I cannot totally stay away from others who had the vaccine. I say this because I can’t quarantine myself in my home all flu season. How do I know who in the public has had the vaccine? In addition, Swine Flu is ALL around me when I’m in public, based on what I’m seeing in the clinic. I use common sense precautions at work (I don’t have a lot of patient contact normally, although I do on occasion); I wear a mask around patients with flu symptoms, I wash my hands or use hand sanitizer frequently, and keep a heightened awareness of those around me who are sick.
I did get the vaccine for seasonal flu, as I have for the past 18 years, long before my kidney transplant (one episode of influenza and it’s accompanying symptoms that make you feel like you will die spurred me to get the vaccine early in my career).
As for the Swine Flu vaccine, the transplant center I go to has been non-committal about whether we should get it.
I most likely will get it when it is available. My line of thinking on this is that it’s the same base vaccine as I’ve always received, the only difference being that it contains the Swine Flu strain, whereas the Seasonal vaccine contains the seasonal flu strains. Also, H1N1 at this point is widespread, but what if the virus mutates and becomes more virulent? What if it becomes resistant to Tamiflu? It’s all about risk vs. benefit.
Hope this helps.
No...the nasal is live. Injection is dead.....
Excellent reply! Thanks for the info. Just what I wanted to know. Plus some other good info about transplants/immune system.
then those infected should stay home for a week or more.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.