Feb 16 2014, 10:44am CST | by Forbes
A Duke University Medical Center study released this past week shows that among this season’s influenza patients sick enough to end up in their intensive care unit, 91% had failed to receive this year’s seasonal flu vaccine.
And for those admitted to the hospital, but with less severe disease not requiring an ICU stay, 67% weren’t vaccinated.
(Disclosure: I’ve held an unpaid, adjunct faculty appointment in Duke University’s Department of Medicine since 2002.).
The study was published online Monday in the American Journal of Respiratory and Critical Care Medicine.
The Duke study examined only the 55 patients admitted to this tertiary-care hospital between November 1, 2013 and January 8, 2014. But the cases were very well-characterized and represented substantial racial diversity, with the patients self-identifying as 47% Caucasian, 42% African-American and 6% Hispanic.
The median age of the patients in the study was 28.5, with 49% of them aged 18 to 49. Another 33% were in the 50 to 64 age group.
These numbers – 8 out of 10 seriously ill patients being young- or middle-aged adults – are consistent with the national trend observed with this year’s most prevalent circulating flu strain, called 2009 pH1N1*. This distribution stands in contrast to most years where infants, toddlers, and seniors are most at risk, although these groups are always at high risk every year.
The researchers also looked closely at the hospitalized patients who received the flu vaccine within two weeks of their hospitalization in hopes of determining how they still ended up sick. The two vaccinated patients of 22 that still ended up in the ICU had disorders that likely rendered them immunocompromised and less likely to mount a sufficient, protective response to the vaccine. Similar confounding situations that would likely suppress immune function were also observed almost all of the non-ICU, hospitalized patients who were vaccinated.
In a telephone interview, Duke infectious disease physician and study co-author, Cameron R. Wolfe, M.D. suggested that public health education efforts might better focus on the major preventive effect the vaccines have on disease incidence and severity.
Wolfe said, “We often talk about the vaccine preventing mortality because that’s the hard, easy-to-measure outcome. But a major point of the paper is that we should also be talking about the vaccines having a separate benefit in terms of morbidity.”
The major, take-home point, Wolfe explains, is that, “Even you get influenza, the vaccine reduces the likelihood of truly serious disease.”
Being admitted to an ICU with respiratory complications of influenza presents a far more convoluted hospital experience than for those who only required three or four days of treatment on the general medicine service.
“These people on the intensive care unit are very sick. If you end up there, you’re going to be battling a month or more of hospitalization,” says Wolfe.
“Some of the people we report on in the paper are still in the hospital. And if you survive, you’re looking at many weeks of rehabilitation.”
In fact, five of the 22 ICU patients had died by the time the paper was accepted for publication.
Across North Carolina, where Duke is located, public health officials said Friday that seven more influenza-related deaths were reported for the week ending February 8th, bringing the state’s total influenza death count to 64 for this season.
Don’t withhold antiviral drugs
Wolfe and colleagues also raised a serious concern regarding the effectiveness of the rapid influenza diagnostic test (RIDT) used both in doctor’s offices in the community and hospitals. About a third of the patients in the ICU had previously received a negative influenza test result. Unfortunately, this high false negative rate appears to have delayed many of the patients from getting antiviral drug therapy, most commonly oseltamvir phosphate (Tamiflu; Genentech) or, to a lesser extent, zanamivir (Relenza; GlaxoSmithKline).
In citing a large, meta-analysis that concluded that the RIDT is only about 63% accurate, the authors stated that:
“The CDC recommends that the decision regarding antiviral treatment of influenza should not await laboratory confirmation and that indications for antiviral treatment include hospitalization, severe complicated and progressive illness, and presence of risk factors for influenza complications, independent of the duration of symptoms.”
Dr. Wolfe added, “The physiological cost of the drug is small [in terms of side effects], the financial cost of the drug is small – so we argue to put the patient on the drug immediately.”
If subsequent testing is negative by the more accurate polymerase chain reaction (PCR) test of samples obtained from deeper in the lung, Wolfe says the drug can always be discontinued.
Yes, you can (and should) still get your vaccine
We’ve all heard public health officials urge us to get one of the vaccines for influenza. True influenza-related illnesses, not just those colds that we call “the flu,” cause between 3,000 and 49,000 deaths in the U.S. each year.
But in support of the protective effect of the vaccine on morbidity, as alluded to by Dr. Wolfe, the CDC estimates that last year’s vaccine prevented 79,000 influenza-related hospitalizations and 6.6 million illnesses. The remarkable success of the vaccine isn’t always at the forefront of public perception because, as with all public health measures, we don’t see the disease cases that were prevented.
As shown in this study, this year’s vaccine was very likely to protect a representative subset of flu patients from serious, potentially fatal respiratory illness. Moreover, the results from Wolfe and colleagues strongly argue the need for people 18 to 64 to be vigilant every year and get their seasonal influenza vaccine. This is especially true in individuals with an underlying predisposition to respiratory diseases such as asthma or other conditions such as diabetes and cardiovascular disease.
Even now in mid-February, it’s not too late to get your vaccine, as 29 states are still reporting widespread flu activity as of February 1st.
Since the vaccine takes 10 to 14 days to elicit a protective immune response, Dr. Wolfe says that getting it in the next two weeks is critical. And for people with allergies to eggs, the production system for most flu vaccines, an egg-free vaccine called Flublok is now available from Protein Sciences.
Influenza-like illness, the type reported from outpatient clinics, is especially high in Texas, Oklahoma, Kansas, and Arkansas. See the CDC’s interactive Fluview page for the latest information.
*The precise strain is A/California/7/2009/(H1N1)pdm09-like virus. The other influenza A hemagglutinin antigen in the 2013-2014 vaccines was from an A/(H3N2) that’s antigenically-similar to the cell propagated virus, A/Victoria/361/2011. The HA protein of an influenza B strain, B/Massachusetts/2/2012-like (B/Yamagata lineage) virus, was also included in this season’s vaccines. The two influenza A strains are the same as those in the 2012-2013 vaccines.
Source: Forbes Business
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