False Negative Swine Flu Tests

Nurses COVID



It may be happening more than we ever realize, those negative test results occurring in patients with real flu like symptoms, that is. The CDC admits these flu tests are not always accurate. It took 3 tests for them to get a positive result in this now terminal case. Now, this is not so unusual a happening, say with the H5N1 bird flu virus, and there it is certainly cause for concern with such a virulent virus, but this Utah woman was diagnosed eventually with the supposedly "mild" swine flu virus. It is not really so important that we always know if someone has swine flu or not, UNLESS they are very sick. If they are, and it really is influenza despite that negative test result, not treating with Tamiflu within the first 48 hours could cost a life.

Indonesian physicians experienced by now in treating H5N1, bird flu cases already know about this. We could benefit from their experience. If they have a very sick patient, and the case looks like bird flu, they treat it with Tamiflu even if the test comes back negative especially if there is another positive case in the family. If they don't, the patient dies. This seems rather elementary, but I guess it is not.

There are many reasons why truly positive cases will return a negative test result. Poor technique in the collection process, improperly stored or handled specimens, a primer that is not up to date with the strain of virus being tested, and even collecting the specimen during the wrong stage of illness will affect the results.

One other reason not relative to this post, but something probably seen rather often in Indonesia, is that if you treat with Tamiflu and then test, your patient is likely to test negative. This is what is seen when "the Tamiflu Blanket" is applied. The Indonesians would blanket a family or an entire village with Tamiflu sometimes when it appeared that cases were spreading human to human in certain parts of the country.

I am fairly certain that there are some other terminal cases that were misdiagnosed or diagnosed only after death. I do know that Judy Trunnel, that unfortunate pregnant woman who died in Texas was only diagnosed at autosy, but I don't know if she was tested before that so if anyone does know about this please post it, or I will look later today. And, the other terminal pregnant case in El Paso, Texas, who died is another one to check on...

I would like to get a sense for how often this may be happening.

Cyndi Bemis, a spokeswoman for the Utah Department of Health, confirmed the adult who died Saturday was a woman but said she did not know if underlying health problems were a factor.

A family member identified the woman as Francine Rushton, 47, and said she contracted the flu about two weeks ago but was initially told it was not the H1N1 type, despite her mother's diagnosis with H1N1 that week.

"She tested negative, so they sent her home and told her to get fluids and rest," said Craig Whitehead, Rushton's brother. Because her mother's health had improved on Tamiflu, the family "begged them to administer Tamiflu" to Rushton, Whitehead said. Doctors said they would not without a positive flu test.

Rushton's third test came back positive, more than a week after she first fell ill, Whitehead said. "By then it was too late," Whitehead said.

Rushton's family is urging flu patients to be vigilant about their symptoms and assertive in seeking treatment.

"Don't take it lightly," Whitehead said. "I sat at work three weeks ago and scoffed, 'What's the big deal?' ... Now I feel differently about it."

There have been 688 confirmed cases of the flu in Utah, including 25 cases among health care workers. A majority of those diagnosed with the virus in Utah have been between the ages of 5 and 24.

(hat tip pfi/howmanydays)

indigo girl

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Hospital defends actions in care of Utah flu victim


In a statement, Jordan Valley Medical Center said it cannot comment on the specific case but added that for any patient with the virus, "we can confirm that all established CDC guidelines are followed during their course of treatment."

Two rapid diagnostic tests conducted by the hospital indicated Francine Rushton, 47, did not have the flu. So she did not qualify for antiviral medication under state and federal guidelines -- despite the rapid test's high false-negative rate, her flu-like symptoms and her contact with her mother, who did have a confirmed case.

The Utah state epidemiologist, while not commenting specifically on the woman's case, said Monday doctors need to exercise their own clinical judgment rather than relying strictly on the test or treatment guidelines.

The H1N1 flu is now so widespread in Utah that a person with a fever, cough and sore throat can be presumed to have the flu unless there is some other obvious explanation, said Robert Rolfs, of the Utah Department of Health.

"If that person also was exposed to somebody who has influenza it makes it even more likely they have influenza," said Rolfs. "At this point, it's common enough I think it is quite reasonable to treat them [as a flu patient] whether or not that rapid laboratory test tells them they have influenza."

Rolfs also said that anyone who tests positive for Type A influenza, "it really tells you they have the H1N1 virus because that is all that is circulating right now." And someone sick enough to be hospitalized should be treated, he said.

Rushton, 47, became ill a day after her mother was positively diagnosed with the flu on May 30 at an urgent care clinic. Rushton, who was living with her mother, visited the same clinic but was told her flu test was negative, said her brother Craig Whitehead.

"They got sick at the same time, within 24 hours," he said.

Three days later, Rushton went to Jordan Valley Medical Center but a second test came back negative. She was sent home and told to drink fluids and rest, her brother said. "We begged the doctors to treat her with [the antiviral] Tamiflu because it had helped her mother, but they refused because her test had come back negative," Whitehead said in a statement. He said Monday that physicians there "didn't think them living together, eating together was big enough factor to treat her."

Rushton continued to deteriorate and three days later returned to Jordan Valley, where she was admitted. But a third test for the flu again was negative.

She was transferred to Intermountain Medical Center in Murray on June 9 in critical condition. A day later, a test for Type A flu finally registered positive and a day later further testing confirmed Rushton had H1N1 flu, Whitehead said. But it was too late to save her.

"IMC hospital -- we want to thank them, they did a great job," he said. "We love the effort put out to help her. The shock and trauma unit was unbelievable in trying to save her life."

The rapid influenza antigen test used in health clinics and doctor's offices to make an initial flu diagnosis has a sensitivity rate of 50 percent to 70 percent compared to viral tests done in a lab, according to the CDC.

"However, much lower sensitivities have been reported," said Tim Uyeki, a physician with the CDC's influenza division. "False negative results clearly occur. This means that a fair amount of infections are missed by this test."

Rolfs said that "depending on the test, depending on the situation, [the test] may miss half of the people who have it. So those tests are not perfect."

False negative results are more likely when disease prevalence is high, the CDC said.

"Clinicians may consider using rapid diagnostic tests as part of their evaluation of patients with signs and symptoms compatible with influenza, but results should be interpreted with caution," the CDC said in a May 2 report.

The brief said the H1N1 flu cannot be excluded based on a negative rapid antigen test, and that in patients who have had contact with someone with a confirmed case of the flu additional testing and treatment may be warranted.

Current CDC and state health department guidelines current recommend use of the antiviral medication only for high-risk patients, even when close contact with someone with a confirmed case has occurred.

Uyeki said in an e-mail to the Tribune that transmission of the new virus is not completely understood. "There are many unanswered questions about this virus that CDC scientists and others are working to address," he said.

Rolfs said health care officials don't know what to expect from the virus next flu season.

"Some of the past pandemics have started out like this -- relatively mild -- and become much more serious," he said. "But there have also been times when it started out like this and didn't get much more serious. We are preparing in case it does get worse. I hope it doesn't."


indigo girl

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Tamiflu for 'the sickest'


Posting this here because the Australian Tamiflu decision may come back to haunt them later. We are seeing there as well, problems with the rapid flu tests, and misdiagnoses complicated by co-circulating seasonal influenzas.

Influenza specialist Dr Rod Pearce says test times for swine flu are taking longer, putting more people at risk of developing the virus before they can be treated.

Mr Hill says initially Tamiflu was prescribed to suspected cases to try to halt the spread of the virus, but that is no longer viable.

"We have to make sure we fairly distribute this, and the commonwealth is responsible for doing this," he said.

"We just don't give it to anybody who's got a flu-like symptom, because if you were to do that you'd run out of it pretty quickly, so it has to go to those who are the sickest."

Wrong diagnosis

Another student from Westminster School at Marion has tested positive for swine flu.

The year 11 girl, who is 16, has been diagnosed after a classmate was found also to have swine flu.

Westminster principal Steve Bousfield says the latest student went to the doctor with flu symptoms last Friday but had been diagnosed with regular influenza and sent home.

He said a test done on Sunday returned a positive result for swine flu.

indigo girl

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Suriname Cases


11 of 16 volleyball players who last week participated in a tournament in Trinidad and Tobago were tested positive for the H1N1 influenza virus.

While a rapid test from the Bureau of Public Health (BOG) on Thursday came back negative, samples from the players were sent to the renowned Pasteur Institute in Cayenne, French Guiana. On Sunday the health autorities here were informed by e-mail that 11 of the volleyballers had tested positive for the H1N1 virus. The same samples are being sent thia week to the Caribbean Epidemiology Centre (CAREC) in Port-of-Spain, Trinidad and Tobago, for a second opinion.

"However we don't expect to get a different outcome," said Waterberg. He further noted that meanwhile all the infected players are recovering spontaneously and very well and should receive a clean bill of health within days.

"There is no reason for panic, but we all have to be vigilant in order to contain the virus," he added.

Meanwhile, family members and contacts of the volleyball players are being screened for the influenza virus. Those who are showing influenza-like symptoms are being advised to stay home, and consult a doctor if the infection persist.

According to Health Minister Waterberg currently there are 1,000 units of Tamiflu in stock, while another 100,000 units are being imported. The official warned, however, that this medication would only be prescribed to patients with a weak resistance and patients who have a serious lung or heart condition.

indigo girl

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A fifth person has died from swine flu in Utah. The latest victim is a 58-year-old woman.

In several of the four other fatal cases of swine flu, the victims had tested negative for the H1N1 virus prior to their deaths. State epidemiologist Dr. Robert Rolfs say despite CDC and state health department guidelines, physicians need to use their own good judgment and not rely on rapid outpatient tests, which may not be accurate.

"If you're a clinician in Utah right now, we have a pretty vigorous transmission of this virus. If I see somebody who seems like they have influenza and I only have a rapid test, I would be inclined to trust my clinical judgment right now even if the test is negative," he said.

In most cases, rapid testing for conventional seasonal influenza is 70 percent reliable. It's less reliable for the H1N1 virus.

Dr. Rolfs says the vast majority of those people with swine flu will get better without medical help. The state reserves its own slower, more accurate testing for the small percentage of people who are hospitalized.

Despite sickness levels, Dr. Rolfs says the total H1N1 cases, including hospitalizations, are comparable to what the state would normally see in a seasonal "moderate" influenza outbreak.


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quote from op of indigogirl:

"the rapid influenza antigen test used in health clinics and doctor's offices to make an initial flu diagnosis has a sensitivity rate of 50 percent to 70 percent compared to viral tests done in a lab, according to the cdc.

"however, much lower sensitivities have been reported," said tim uyeki, a physician with the cdc's influenza division. "false negative results clearly occur. this means that a fair amount of infections are missed by this test." rolfs said that "depending on the test, depending on the situation, [the test] may miss half of the people who have it. so those tests are not perfect." " which makes the public health stats poorly indicative of the actual incidence of this disease!


as i recall, the cdc recommended early in this pandemic episode, that anyone with flu s/s should be treated "as if" they had h1n1, and that the unreliability of the test would justify skipping it (or something like that).

i posted somewhere on another thread, that i had flu s/s in early may and although my h1n1 test was negative, the doctor at "medexpress", where i went for care, (rather than expose patients in an er to my possible communicability) prescribed tamiflu and doxycycline (for later secondary infection prevention).

he explained that the tests function better as an indicator of h1n1, later in its disease process, but since i was in the first 48 hours of my illness, tamiflu had to be given then, to be effective. i was very impressed with that doctor's knowledge, early on; and so i was compliant in filling the prescription and taking it (which often may not be done by many patients).

p.s. the cost of the test was $82.

indigo girl

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Good points, lamazeteacher, and I am glad that he had the sense to give you the Tamiflu even with a negative test result because as you know, not all places are doing this.

Here is another case of what appears to be a negative rapid flu test. I think that they probably treated this poor child anyway but it was too late. Confirmation of swine flu infection came only after his death.


A 9-year-old boy who died in a Miami-Dade hospital last week had swine flu, officials said Tuesday.

Officials did not disclose the boy's name, school or hometown, but they said he lived in Miami-Dade County.

Dr. Fermin Leguen, chief physician for the county's health department, said the boy was brought to Baptist Hospital in Kendall on June 9 within 24 hours of showing flu-like symptoms. The boy died at the hospital the same day.

"This child had a history of asthma," said Leguen. "He had developed an acute respiratory illness."

After the boy died, health officials sent tissue samples to a Florida Department of Health Laboratory in Tampa. It took a week to confirm the boy had contracted the swine flu virus.

indigo girl

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Of Wisconsin's nearly 3,500 confirmed or probable swine flu cases as of Friday, 74 percent were people under the age of 19, said Seth Boffeli, a spokesman for the state Department of Health and Family Services.

"We are watching closely that such a high percentage of those infected are school-age children," he said.

More traditional, seasonal flu strains generally hit elderly people the hardest, at least hard enough for them to see a doctor more than younger people, he said.

Wisconsin health officials have reported three additional deaths since June 11, including Emily Eaton of Wausau. She died Wednesday at St. Joseph Children's Hospital in Marshfield.

Her father, Dale, said Friday the family has no idea how the recent sixth-grader contracted the illness. She was admitted to a Wausau hospital early June 12 for what appeared to be a case of pneumonia and the rapid test for swine flu was negative, the father said. Her condition worsened by June 13 and she was transferred to the Marshfield hospital, where more testing discovered swine flu.

His daughter was particularly vulnerable to the H1N1 virus because she suffered from episodic immune deficiency since birth and she had a mild form of autism, he said.


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Hmmmmmm........episodic immune deficiency with autism........ ?? connection???

Actually I've never heard of "episodic" immune deficiency other than that which has been documented during stressful, sleep deprived, and post illness/surgical situations and extreme physical exertion, when any of us could be described that way.

Autistic persons are more stressed, could be sleep deprived due to frequent nightmare-like brain activity during sleep; and they often exhibit long periods of extreme activity. When I worked a summer with developmentally disabled teens at a high school, we were able to slow down an autistic 17 year old's repeatedly injurious (to herself and others) behavior, by placing her in a cozy ceiling suspended "individual hammock" swing.

That might calm many of us down. I must try that when I get upset by some of the posts I see (not in this thread, of course).


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Quick question - what are the early signs and symptoms of H1N1? I work occasionally in a small community hospital ER, and am very interested in the information you're posting. Thank you, Indigo Girl and others.

indigo girl

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Swine flu looks like any other flu although with this flu there can be GI symptoms as well, and not just in kids. There may be fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. Not everyone presents with fever either. Most cases will be mild, but if the patient says that they feel really bad, and the family dragged them to the ER, I would be more concerned. Yes, I know that some will overreact also...

Some docs are going to err on the side of caution and prescribe Tamiflu to those people with s/s whether or not the rapid tests come back positive if the patient has any obvious risk factor such as a reactive airway disease (asthma, COPD), or is diabetic, or pregnant. They will also have to look at the clinical picture. Is the patient fragile in some way such as a child with autism, Down's syndrome, an elderly person, or someone with immune problems? But, are they going to consider smokers at risk also? Probably not, although they most likely are. The obese? They are also. It's a tough call. How obese does someone have to be? I hope that there are some very good clinicians out there to make these tough calls.

And then there are those that have no risk factors...It is not going to always be clear, and you are going to lose some of these people. That is the hardest thing to accept, and it is already happening now even though it is summer. With the expected increase of cases during our regular flu season, there are likely to be many more deaths.

We do not have unlimited supplies of Tamiflu, and test kits, so not everybody that comes in to a doctor's office, urgent care or the ER is going to be tested or given this drug. Yet, it must be given within 48 hours of getting sick for it to be most effective.

I do not envy anyone who works in the ER especially not this coming fall/winter. Your job is hard enough already. It is going to get harder.


The debate over relying on laboratory tests vs. going with a doctor's clinical assessment (or `sense') is an old one, and not restricted to this flu outbreak. Most doctors recognize the importance of treating the patient, not the lab report.

Unfortunately, there are a plethora of pathogens that can produce influenza-like symptoms in a patient. Parainfluenza, respiratory syncytial virus, metapneumovirus, influenza B, and adenovirus are just a few, and differentiating between them is nearly impossible.

Luckily, this time of year in the northern hemisphere, most of these viruses are near their low ebb for the year. During the winter, when these viruses abound, it becomes much more difficult discerning which are influenza `A'.

Swine Flu Warning Signs That Someone Is Going Sour


In children, signs that need urgent medical attention include fast breathing or trouble breathing; blueish or gray skin color; not drinking enough fluids; severe, persistent vomiting; not waking up or not interacting.; being so irritable that the child doesn't want to be held; and flu-like symptoms improve, but then return later with a fever and a worse cough. Those are warning signs we physicians think about all the time, with respiratory infections. And they're good to have in mind with this new influenza-like illness caused by the novel H1N1 strain. Just good things for parents to have in the back of their mind.

In adults, we look at another set of warning signs that suggest the need for urgent medical attention: difficulty breathing or shortness of breath; pain or pressure in the chest or abdomen; sudden dizziness, confusion, persistent or severe vomiting that doesn't go away; and flu-like symptoms that improve, but then come back again with a fever or worsening of cough. (Statement by Dr. Anne Schuchat, CDC Press Briefing, May 28, 2009)


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Thank you, Indigo! This is very helpful information :)

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