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 Post subject: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 5:15 am 
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I sent my 11-year-old son to school today with a stuffy nose and mild cough, as I've done countless times in the past. Now, though, I'm wondering whether I should have kept him home. How do I know it's really a garden-variety cold and not the swine flu?


"That's a great question," says Richard Wenzel, a swine flu expert and former president of the Infectious Diseases Society of America. "You really have no way of knowing if it's the flu or just a cold." Given that we're in the middle of an H1N1 epidemic, he estimates that my son's chances of having this flu are considerable, since some of his friends have had confirmed cases--maybe even as high as 50/50. Even though he doesn't have fever? I press. "At the beginning of the outbreak in Mexico, only 30 percent of patients hospitalized with the infection had fever initially," he tells me, "and 15 percent of patients never developed a fever at all." What usually sent them to the hospital was shortness of breath or chest pain. In Chile, he adds, about half of those with confirmed H1N1 had no fever; many just had a headache and runny nose.


To truly contain the spread of this virus, he says, it would have been smart for me to keep my son home from school. While I can work effectively from home, many working parents can't. I wonder if this is why the government isn't recommending that we keep ourselves or our kids home at the first sign of a sniffle. The Centers for Disease Control and Prevention says: "Those with flulike illness should stay home for at least 24 hours after they no longer have a fever, or signs of a fever, without the use of fever-reducing medicines." That implies that hacking coughs and runny noses shouldn't keep us away from others.


"The CDC is stuck. They've defined flu as having a fever, which means they're going to miss a lot of cases," Wenzel says. To be fair, the CDC does list the following as symptoms of H1N1: cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue, and, in some people, diarrhea and vomiting. But fever seems to be the determining factor in whether we should isolate ourselves.


Since most doctors aren't testing for H1N1, we must use our own judgment to decide if that mild cold warrants taking sick days and keeping our kids home from school for up to a week. We might be helping prevent the spread of a potentially deadly virus. Then again, it might be pointless if others are going about their usual day coughing and sneezing around others. (Hopefully, they're washing their hands frequently and coughing into their elbows.) After speaking with Wenzel, I might keep my son home tomorrow--especially if his symptoms get worse.


"This flu seems to spread more easily than a cold virus or seasonal flu," says Wenzel, "most likely because so few people have been exposed to it in the past." Kids are slated to be among the first to get the H1N1 vaccine when it becomes available in early October--a nasal spray vaccine called FluMist will the first on the market. But many will probably already have been infected before they can get immunized; Wenzel predicts the outbreak will last another four to eight weeks before tapering off. Unfortunately, that's just around the time when the vaccine will be available in large quantities. It seems that despite the government's best efforts to get the vaccine out quickly, it missed the boat on this one.


Yes, the CDC will still stick with its recommendation to get any children over the age of 6 months vaccinated--and pregnant women too--unless a previous infection was confirmed via a lab test. But Wenzel says parents may decide on their own to pass up the immunization if their child recently had a respiratory infection that appeared to be swine flu. "These kids probably don't need the vaccine," he adds, "but there's a level of uncertainty, and parents may still be wise to choose immunization just to be on the safe side."


While most cases of H1N1 are mild, this virus has the potential to cause severe complications, including death. The CDC says warning signs in children that warrant immediate medical attention include fast breathing or trouble breathing; bluish or gray skin color; not drinking enough fluids; severe or persistent vomiting; not waking up or interacting; a child so irritable that he does not want to be held; and flulike symptoms that improve but then return with fever and a worse cough. Warning signs in adults include difficulty breathing or chest pain, purple or blue discoloration of the lips, vomiting and inability to keep liquids down, and signs of dehydration, such as feeling dizzy when standing or being unable to urinate.


http://news.yahoo.com/s/usnews/20090921 ... toughcalls

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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 8:05 am 
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Amazing how we point these things out months ago. Maybe reporters should come here to learn how to report on H1N1 :yahoo:


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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 8:14 am 
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niman wrote:
"The CDC is stuck. They've defined flu as having a fever, which means they're going to miss a lot of cases," Wenzel says. To be fair, the CDC does list the following as symptoms of H1N1: cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue, and, in some people, diarrhea and vomiting. But fever seems to be the determining factor in whether we should isolate ourselves.

http://news.yahoo.com/s/usnews/20090921 ... toughcalls

Fever is the determing factor for students. When they go to the nurses' office and do not have a fever, they STAY in school. Most without fever never see the nurse (or their doctor) and continue to go to school, even though they are infectious.

In the recently published cliniccal trial in Australia, confirmed H1N1 excluded the subject for participation but over 31% have protective H1N1 antibody titers BEFORE (at baseline) they received the vaccine. Thus, unconfirmed H1N1 is widespread becasue those without fever are not tested and therefore not confirmed.

At baseline, 76 of 240 subjects (31.7%) had antibody titers of 1:40 or more on hemagglutination-inhibition assay

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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 10:19 am 
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niman wrote:
niman wrote:
"The CDC is stuck. They've defined flu as having a fever, which means they're going to miss a lot of cases," Wenzel says. To be fair, the CDC does list the following as symptoms of H1N1: cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue, and, in some people, diarrhea and vomiting. But fever seems to be the determining factor in whether we should isolate ourselves.

http://news.yahoo.com/s/usnews/20090921 ... toughcalls

Fever is the determing factor for students. When they go to the nurses' office and do not have a fever, they STAY in school. Most without fever never see the nurse (or their doctor) and continue to go to school, even though they are infectious.

In the recently published cliniccal trial in Australia, confirmed H1N1 excluded the subject for participation but over 31% have protective H1N1 antibody titers BEFORE (at baseline) they received the vaccine. Thus, unconfirmed H1N1 is widespread becasue those without fever are not tested and therefore not confirmed.

At baseline, 76 of 240 subjects (31.7%) had antibody titers of 1:40 or more on hemagglutination-inhibition assay


I sincerely hope that you are correct and that widespread exposure to a relatively mild strain has partially immunised a very significant percentage of the population (at least in Australia) but I note that the authors make some comments on this which might suggest it's not quite as good as it looks.

http://content.nejm.org/cgi/content/full/NEJMoa0907413

Of the 240 subjects, 45.0% reported having received a 2009 Southern Hemisphere seasonal trivalent inactivated vaccine. The proportion of subjects who received the 2009 seasonal vaccine did not differ between the age groups (P=0.24 by Fisher's exact test).
...

Immunogenicity

At baseline, 76 of 240 subjects (31.7%) had antibody titers of 1:40 or more on hemagglutination-inhibition assay (Table 2 and Figure 2A and 2C), with no significant differences between either age groups (P=0.21) or dose groups (P=0.68). Similarly, there were no significant differences in baseline geometric mean titers (GMTs) between age groups or dose groups (Table 3). Of note, baseline titers of 1:40 or more on hemagglutination-inhibition assay were observed in 48 of 108 subjects who had received the 2009 seasonal vaccine (44.4%; 95% confidence interval [CI], 35.4 to 53.8), as compared with 28 of 132 subjects who had not received the seasonal vaccine (21.2%; 95% CI, 15.1 to 28.9; P<0.001 by Fisher's exact test).

...

The proportion of subjects with titers of 1:40 or more on hemagglutination-inhibition assay at baseline was higher than expected. Among subjects who were 50 years of age or older, this finding could be attributed to the presence of preexisting antibodies from exposure to H1N1 viruses circulating before 1957.23 It was surprising, however, to see similar baseline antibody titers in the younger age group. A number of factors could have contributed to the observed titers in both age groups at baseline. It is probable that there was some degree of previous 2009 H1N1 infection in the study population, despite stringent exclusion criteria. Cross-reactive antibodies to 2009 H1N1 may also have played a role. In this issue of the Journal, a ]study by Hancock et al. that analyzed stored-serum samples from trials of seasonal trivalent inactivated vaccine predating the current pandemic showed the presence of cross-reactive antibodies to 2009 H1N1 in adults.24 The same study showed that vaccination with the seasonal vaccine resulted in a doubling in titers of these cross-reactive antibodies. The latter finding is particularly relevant, given that 45% of the subjects in our study had received the 2009 seasonal vaccine.

====================
If I am reading the above correctly then only 20% of subjects who had not received the seasonal vaccine had baseline titers of 1:40 or more. We are also told that the proportion of those who had received that vaccine was constant across age groups. They don't seem to break this down any further but it would seem to suggest that much of that 20% baseline protection in those who did not receive the seasonal vaccine would be in the older age group who we know already have some pre-exposure. Guessing here but that might imply that perhaps only about 10% of these subjects under 50 actually had pre-existing titers of 1:40 or more? They authors could have included this data in the paper but unless I'm missing the obvious (which is possible!) it is not there. It would be nice to see their "Fig 2" charts but only for those who had not received the seasonal vaccine.


Last edited by Hogweed on Tue Sep 22, 2009 11:02 am, edited 1 time in total.

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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 10:45 am 
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I have to double check, but I don't think the Australian study found signifcant differences in prior H1N1 antibody levels in young and old volunteers.

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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 10:54 am 
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niman wrote:
I have to double check, but I don't think the Australian study found signifcant differences in prior H1N1 antibody levels in young and old volunteers.

On the surface it didn't but about half of their sample in the younger age group had received the seasonal vaccine (here in the UK it would be ludicrous to assume that anything like 50% of those under 50 would have received the seasonal vaccine - so the sample seems biased in the first place). The authors draw attention to this in the report and state that protection levels halved across those taking part if the seasonal vaccine had not been administered first. However they do not break this group down by age despite drawing attention to the high rates of seasonal vaccinations in the sample.

One further point. We don't seem to be given details of the pre-administered "seasonal" vaccine. I guess it might have made a difference to cross-protection if it was an experimental adjuvant "seasonal" vaccine (after all these were trial volunteers).


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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 11:24 am 
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Commentary

http://www.recombinomics.com/News/09220 ... al_Ab.html

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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 11:34 am 
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niman wrote:

Just to be clear I have no doubt that there are a very significant number of undiagnosed cases as you say - I'm just not so sure about it being as high as the Australian research would at first suggest and I cannot figure out why they just didn't publish the data by age group for only those who had not first received the seasonal vaccine (despite going out of their way to suggest that it was "particularly relevant") - that would have answered my question.

I certainly hope that protective levels are as high in general as their sample would indicate.


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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 11:42 am 
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Hogweed wrote:
niman wrote:

Just to be clear I have no doubt that there are a very significant number of undiagnosed cases as you say - I'm just not so sure about it being as high as the Australian research would at first suggest and I cannot figure out why they just didn't publish the data by age group for only those who had not first received the seasonal vaccine (despite going out of their way to suggest that it was "particularly relevant") - that would have answered my question.

I certainly hope that protective levels are as high in general as their sample would indicate.

I suspect the target population is somewhat biased towards those who had the seasonal flu vaccine, in part to see if either age grop benefited from the seasonal flu shot, and in part because such a group would have the potential for giving a better reposnse, but I think that the finding of pandmeic antibody in 31% was a surprise and was due to mild cases, including those without fever.

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 Post subject: Re: Seasonal Cold or Swine Flu? (Lack of Fever in Swine Flu)
PostPosted: Tue Sep 22, 2009 3:32 pm 
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Story is popular

http://www.newsnow.co.uk/h/Hot+Topics/Swine+Flu?type=ts

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