unanswered questions

[vt.mathgirl]

I attended a forum in Rutland Tuesday night, and there were 2 questions that our commisioner of health couldn't answer.

One - what percent of hospitalized patients and/or deaths are people with underlying conditions vs healthy people?

Two - what is the 'hang time' for flu droplets in the air, and is this flu contagious in this way (like measles)?

This forum was sparsley attended, mainly school nurses and such concerned with logistics of holding clinics in schools. There were a few questions about vaccines from concerned parents. Again, not much interest in Vermont, people feel isolated and safe, and our local paper doesn't have much to say.

 

[North44]

Re: unanswered questions

Hi vt.mathgirl,
1) generally, numbers thrown around for healthy people getting very sick or dying from H1N1 is in the neighbourhood of 40 to 50%.
2)H1N1 is definitely spread through fine droplets in the air. In hospital, we are recommended to keep ill patients 2 meters (about 6 feet) away from others. As to how long droplets are suspended, I have not seen any specific data, but I would guess we are looking at under a minute or two. Hope this helps.

 

[gsgs]

Re: unanswered questions

1) you mean: 40% of people who die from H1N1 were healthy before ?
2) depends on the size of the droplet. particles smaller than ~5micron
don't settle at all. (flu-virus = 0.1 micron)
larger droplets e.g. from sneezing fall down directly

 

[North44]

Re: unanswered questions

gsgs,

"1) you mean: 40% of people who die from H1N1 were healthy before ?"

That is my understanding - at least 40%.

 

[vt.mathgirl]

Re: unanswered questions

Newspaper reports usually give some vague statement like 'most' serious cases have underlying conditions. When asked, our commisioner said she didn't know exactly, but felt that perhaps 70-80 percent had underlying conditions. If it's really closer to 50/50 then maybe people would reconsider their level of concern/preparedness.

 

[german-docter]

Re: unanswered questions

I attended a forum in Rutland Tuesday night, and there were 2 questions that our commisioner of health couldn't answer.

One - what percent of hospitalized patients and/or deaths are people with underlying conditions vs healthy people?

Two - what is the 'hang time' for flu droplets in the air, and is this flu contagious in this way (like measles)?

This forum was sparsley attended, mainly school nurses and such concerned with logistics of holding clinics in schools. There were a few questions about vaccines from concerned parents. Again, not much interest in Vermont, people feel isolated and safe, and our local paper doesn't have much to say.

vt.mathgirl :tiphat:

Question 1:
Answer is rather difficult because there are of too much variables, especially differences in national and even local health care systems. That is one of the reasons, the hospitalisation ? fatality rates are quite different. Do people have early and unlimited access to qualified medical care ?, outpatient versus an inpatient strategies ?, early use of antivirals ? and so on.


Question 2:
It would be adequate to make a difference:

A) ?common? droplets with particles of various sizes ( about 10 microns) as an aerosol (?droplet transmission?) produced by coughing, sneezing, talking that will stay in the air at least one minute or some minutes, usually within a range of 3 to 6 feet (1-2 m).

Example: Video Images of a cough New England Journal of Medicine
http://content.nejm.org/content/vol359/issue15/images/data/e19/DC1/NEJM_Tang_e19v1.shtml

B) Small droplet nuclei (?airborne transmission?), containing virus particles, droplet size < 5 (< 2.5) microns, remaining in the air of a room for at least several minutes up to one hour or even for 24 hours (!), depending on relative and absolute humidity, ventilation rate, room size etc.


There is another aspect to think about:

A small amount of viruses in big sneezing droplets only reaching nasal mucosa of a healthy man may not be enough to cause an infection.

The same amount of virus particles in very small droplets, thus able to pass the upper respiratory tract into the lower respiratory tract and even lung alveoli of a smoker with chronic obstructive pulmonary disease may cause a serious infection and fatal pneumonia.

Regarding the small droplet nuclei we only have data of experimental studies (mice and guinea pigs) but with highly interesting results regarding the influence of humidity on transmission rates. Extrapolation to humans remain unclear.


Examples of experimental studies:

Loosli et al. published in 1943 (see NIOSH - CDC presentation 2004: slide 14-16)
http://www.cdc.gov/niosh/npptl/reso...nfluenza Transmission Carolyn Buxton Bridges"

The CDC presentation includes some other interesting issues, e.g. transmissions within airplanes and hospitals.


http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.0030151
Samira Mubareka et al. (2007): Influenza Virus Transmission Is Dependent on Relative Humidity and Temperature

http://www.boneco.ch/en-us/images-ats/PNAS_Article.pdf
Jeffrey Shaman and Melvin Kohn (2009): Absolute humidity modulates influenza survival, transmission, and seasonality


We also do know by some epidemiologic data and case reports that sweeping dust or using vacuum cleaners may contribute to an infection by aerosols and airborne transmission of germs.

http://emergency.cdc.gov/disasters/disease/pdf/diarrhea-evac.pdf
CDC desaster safety. Infection Control Recommendations for Prevention of Transmission of Diarrheal Diseases in Evacuation Centers:
?Do not use a vacuum cleaner to clean up vomit or stool. Wipe up the material with paper towels and dispose of used towels in a plastic garbage bag. Rinse areas with water.?)

 

[Missouriwatcher]

Re: unanswered questions

In children: "To characterize these cases, CDC analyzed data from April to August 2009. The results of that analysis indicated that, of 36 children who died, seven (19%) were aged <5 years, and 24 (67%) had one or more of the high-risk medical conditions. Twenty-two (92%) of the 24 children with high-risk medical conditions had neurodevelopmental conditions. Among 23 children with culture or pathology results reported, laboratory-confirmed bacterial coinfections were identified in 10 (43%), including all six children who 1) were aged ≥5 years, 2) had no recognized high-risk condition, and 3) had culture or pathology results reported." http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a1.htm

In adults and children: "70% of hospitalized had underlying conditions" based on a July 29, 2009 report
http://www.cdc.gov/vaccines/recs/acip/downloads/mtg-slides-jul09-flu/02-Flu-Fiore.pdf

 

[DataMom]

Re: unanswered questions

I just did a quick run-through of Treyfish's list of children who have died from H1N1. This would not be a scientific "study" of course due to selection pressure from the fact that most of these children's deaths were culled from local media reports. I found 16 children died from Pandemic H1N1 who had reported underlying conditions. Also, 16 children died where it was stated that the child was healthy or specifically that the child had no underlying conditions. Then there were 15 where no mention was made of underlying conditions, or it was not known whether there were underlying conditions.

I also remember reading the 40 - 50% figure several times, but could not find the references. I recommend that everyone read through the Dead Children thread.