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Preventing the Flu

Wednesday, March 6, 2013 // Uncategorized

Here is an article from JAMA on addressing the prevention of the fly and answers all the arguments put forth by those who don’t want to be immunized.  Following it is an interesting report from ProMed digest that suggests that maybe the response to the flu vaccine is not as robust in people who have received it the previous year!
 
Viewpoint | March 6, 2013 ONLINE FIRST
Thomas R. Talbot, MD, MPH; H. Keipp Talbot, MD, MPH

Author Affiliations: Departments of Medicine (Drs T. R. Talbot and H. K. Talbot) and Preventive Medicine (Dr T. R. Talbot), Vanderbilt University School of Medicine, Nashville, Tennessee.

 

Following last year’s season of low activity, influenza is surging across the country and as of January 5 has claimed the lives of 20 children.1 With influenza intensifying, it is important to review essential interventions that prevent influenza transmission at home, at work, and in health care facilities.

 

Several important actions should be performed by everyone to prevent the spread of this potentially deadly pathogen. Basic infection control practices such as regularly performing hand hygiene, observing respiratory hygiene and cough etiquette (“cover your cough”), and avoiding others and crowded areas when ill (social distancing) are important prevention methods for any contagious respiratory tract infection. Additional measures to limit transmission of influenza in health care settings are also essential. These include screening patients on arrival to assess for respiratory symptoms, placing a surgical mask on potentially infected individuals, using isolation precautions for those suspected of having or confirmed to have a respiratory tract infection, keeping infected patients away from other patients, and ensuring that visitors and health care personnel (HCP) do not visit or work while ill (ie, “presenteeism”).2

 

Influenza, however, is unique among respiratory viral pathogens in that another effective intervention to prevent transmission exists: vaccination. Annual influenza vaccination has been available in the United States since 1945 and has been recommended for persons at high risk of influenza complications since 1960. Unlike many pathogens, the predominant circulating influenza strains vary from year to year, affecting the intensity and severity of the influenza season as well as vaccine effectiveness. According to a recent systematic review and meta-analysis of influenza vaccine protection, there was 59% effectiveness of the trivalent influenza vaccine in adults aged 18 to 65 years and a higher effectiveness (83%) of the live-attenuated vaccine (LAIV) in children.3 Although not at levels of other vaccines, influenza vaccination provides some protection and may prevent complications due to influenza such as pneumonia, hospitalizations, and death. Recent studies in children have demonstrated that the inactivated influenza vaccine is 55% effective against any illness due to laboratory-confirmed influenza but 73% effective against any moderate or severe disease due to influenza.4 Hence, vaccinated patients may still develop influenza infection but are likely to be at lower risk for its associated complications.

 

However, vaccination rates, particularly for individuals of high risk (eg, due to comorbid conditions) and high transmission risk (eg, HCP who have frequent contact with high-risk patients), remain unacceptably low. For the 2008-2009 influenza season, only 28.2% of all adults aged 18 to 64 years and 41.4% of those with a high-risk condition received an influenza vaccine.5 While rates among HCP are increasing (in part due to policies whereby vaccination is a condition of employment and credentials), one-third of HCP were not vaccinated last year, potentially increasing the risk of transmission to their patients, coworkers, families, and friends.6 Assessments of why people refuse influenza vaccination often reveal similar themes. We provide perspectives to some of the reasons.

 

“The vaccine does not work.” Even though influenza vaccine is not as effective as other common vaccines, “not as effective” does not mean “not effective.” The Centers for Disease Control and Prevention’s midyear assessment of this season’s influenza vaccine’s effectiveness is 62% (95% CI, 51%-71%) for the prevention of medically attended acute respiratory illness.7 There also is a relatively good match between circulating and vaccine strains and, as a result, some mitigation of influenza morbidity. A prevention measure that reduced the risk of a serious outcome by 60% in most instances would be a noted achievement; yet for influenza vaccine, it is seen as a “failure.” Clearly, a better influenza vaccine, particularly a universal antigen vaccine that protects over several seasons, is needed, but this should not be a reason to neglect the current vaccine.

 

“The vaccine causes the flu.” The currently licensed influenza vaccines are LAIV and the inactivated vaccine. Neither vaccine can cause influenza infection. The LAIV is an attenuated live viral vaccine with a temperature-sensitive adaptation that precludes replication of the virus at human core body temperatures. Secondary transmission from a person recently vaccinated with LAIV resulting in clinically important illness has not been reported.8 The inactivated vaccine contains only killed virus and viral antigens and also cannot cause influenza infection. Placebo-controlled randomized trials have not noted a higher frequency of systemic reactions in vaccine recipients when compared with those receiving placebo. Undoubtedly, people may develop an influenza-like illness or even laboratory-confirmed influenza after vaccination. This does not mean the illness was vaccine induced but rather was likely due to a noninfluenza viral infection (as other viruses, such as respiratory syncytial virus, also circulate during influenza season), exposure to influenza before immunity from the vaccine had time to develop, or the fact that the vaccine is not 100% effective.

 

“I have an allergy to eggs.” For many years, egg allergy was a contraindication to influenza vaccination, and those with severe allergic reactions (ie, anaphylaxis) should still avoid influenza vaccination. However, recent evidence-based guidance advises that all other egg-allergic patients should receive influenza vaccination based on the rationale that the risks of not vaccinating outweigh the risks of vaccinating these individuals as long as basic precautions are followed. Specifically, the Advisory Committee on Immunization Practices advises that those with an egg allergy who have only experienced hives after egg exposure should receive influenza vaccine with postvaccination observation for 30 mintues.9 However, egg-allergic patients with a history of angioedema, respiratory distress, nausea, vomiting, or a reaction that required epinephrine or emergency medical attention after egg exposure should be referred to an allergist for further evaluation.

 

“I cannot get the vaccine because I am pregnant or have an underlying medical condition or because I live with an immunocompromised person.” Refusing vaccination because of underlying conditions such as pregnancy or history of organ transplantation may actually harm those at greatest risk of complications from influenza. For years, these groups have been specifically recommended for influenza vaccination because the vaccine is safe in these persons and can prevent serious morbidity and mortality. In such instances, it is important for clinicians to recognize the individual’s desire to prevent harm in close contacts but to redirect this good intention by emphasizing the morbidity due to transmitted influenza.

 

“I never get the flu/I am healthy.” This rationale neglects one of the major reasons vaccination is recommended. While some people, such as healthy adults, may not develop a classic, severe influenza-like illness when infected (and a substantial proportion may have minimal to no symptoms),10 they likely still can transmit the virus to others. Refusing vaccination because of a perceived low risk ignores the potential risk to close contacts, especially those who cannot get vaccinated or who will not mount a strong immune response to the vaccine and rely on herd immunity for protection. This risk has driven many health care facilities to require influenza vaccination for their HCP as a professional and ethical intervention to protect patient safety and promote a safe workplace.

 

The increasing incidence of influenza across the United States should remind all clinicians about the key methods for transmission prevention, including vaccination. Misperceptions about influenza vaccine are common and often deeply rooted; for the protection of patients, colleagues, and loved ones, these perceptions must continue to be addressed, and the approach should be to immunize, immunize, immunize!

AUTHOR INFORMATION

 

Corresponding Author: Thomas R. Talbot, MD, MPH, Vanderbilt University Medical Center, A-2200 Medical Center N, 1161 21st Ave S, Nashville, TN 37232 ([email protected]).

Published Online: January 18, 2013. doi:10.1001/jama.2013.453

Conflict of Interest Disclosures: Both authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr T. R. Talbot reported having served in an advisory/consultant role for Joint Commission Resources. Dr H. K. Talbot reported having received grants from Sanofi Pasteur and MedImmune; having received travel support from Sanofi Pasteur; having received fees for participation in review activities from INC Research and Teva Pharmaceuticals; and having served on a board for the National Foundation for Infections Diseases.

REFERENCES

 

1 +
 Situation update: summary of weekly FluView. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/weekly/summary.htm. Accessed January 14, 2013
2 +
 Prevention strategies for seasonal influenza in healthcare settings. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/professionals/infectioncontrol/healthcaresettings.htm. Accessed January 14, 2013
3 +
Osterholm MT, Kelley NS, Sommer A, Belongia EA. Efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis.  Lancet Infect Dis. 2012;12(1):36-44
PubMed   |  Link to Article
4 +
Jain VK, Rivera L, Chandrasekaran V,  et al.  Efficacy of an inactivated quadrivalent influenza vaccine candidate in children 3-8 years of age [abstract 1793].  Presented at IDWeek Scientific Meeting; October 17-21, 2012; San Diego, CA
5 +
Williams WW, Lu PJ, Lindley MC, Kennedy ED, Singleton JA.Centers for Disease Control and Prevention.  Influenza vaccination coverage among adults: National Health Interview Survey, United States, 2008-09 influenza season.  MMWR Morb Mortal Wkly Rep. 2012;61(suppl)  65-72
PubMed
6 +
Centers for Disease Control and Prevention.  Influenza vaccination coverage among health-care personnel: 2011-12 influenza season, United States.  MMWR Morb Mortal Wkly Rep. 2012;61(38):753-757
PubMed
7 +
Jackson L, Jackson ML, Phillips CH,  et al.  Early estimates of seasonal influenza vaccine effectiveness: United States, January 2013.  MMWR Morb Mortal Wkly Rep. 2013;62(2):32-35
PubMed
8 +
Talbot TR, Babcock H, Cotton D,  et al.  The use of live attenuated influenza vaccine (LAIV) in healthcare personnel (HCP): guidance from the Society for Healthcare Epidemiology of America (SHEA).  Infect Control Hosp Epidemiol. 2012;33(10):981-983
PubMed   |  Link to Article
9 +
Centers for Disease Control and Prevention.  Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP): United States, 2012-13 influenza season.  MMWR Morb Mortal Wkly Rep. 2012;61(32):613-618
PubMed
10 +
Lau LL, Cowling BJ, Fang VJ,  et al.  Viral shedding and clinical illness in naturally acquired influenza virus infections.  J Infect Dis. 2010;201(10):1509-1516
PubMed   |  Link to Article
 
 
INFLUENZA (24): USA, VACCINE EFFECTIVENESS
******************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: Fri 1 Mar 2013
Source: CIDRAP (Center for Infectious Disease Research & Policy) News
[edited]
<http://www.cidrap.umn.edu/cidrap/content/influenza/general/news/mar0113vestudy.html>

Vaccination and protection: Getting flu shot 2 years in a row may
lower protection
– ———————————————————————-
Experts are puzzled by a new study in which influenza vaccination
seemed to provide little or no protection against flu in the 2010-11
season and in which the only participants who seemed to benefit from
the vaccine were those who hadn’t been vaccinated the season before.
[See: Ohmit SE, Petrie JG, Malosh RE, et al: Influenza vaccine
effectiveness in the community and the household. Clin Infect Dis 2013
Feb 14
<http://cid.oxfordjournals.org/content/early/2013/02/14/cid.cit060.abstract?sid=3Dab39e70b-bd2e-476b-b7ff-8b2be85ef28c>].
The investigators recruited 328 households in Michigan before the flu
season started and followed them through the season. Overall, they
found that the infection risk was nearly the same in vaccinated and
unvaccinated participants, indicating no significant vaccine-induced
protection. That contrasted sharply with several other observational
studies that found the vaccine to yield about 60 percent protection
during the same season.

In trying to figure out why the effectiveness was so low, the
researchers sifted their data in different ways, said Arnold S Monto,
MD, of the University of Michigan, senior author of the study. “We
discovered that if you separated out those that had not been
vaccinated the previous year, you got percentages close to what were
seen in the major vaccine effectiveness studies. “We felt it had to be
separated out.” The vaccine was found to be 62 percent effective in
those who hadn’t been vaccinated the previous year. That was similar
to findings in the other observational studies and also to the results
of a recent, rigorous meta-analysis of randomized controlled trials.
In contrast, those who had been vaccinated 2 years in a row (before
both the 2009-10 and 2010-11 seasons) got no significant protection.
An additional finding was that the vaccine did not seem to protect
participants who were exposed to flu in their own household, though
the numbers in that arm of the study were small.

The findings come amid a growing number of studies that raise
questions about flu vaccine effectiveness (VE). They include, among
others, a CDC report that this year’s vaccine has worked poorly in
elderly people and 3 recent European studies showing that
vaccine-induced immunity in the 2011-12 season waned after 3 to 4
months [see ProMED-mail post: Influenza (21): vaccine effectiveness in
seniors 20130222.1555338. Other studies have cast doubt on the
long-standing belief that a close match between the vaccine virus
strains and circulating strains improves VE. Edward Belongia, MD, a
Wisconsin clinician-researcher and member of the CDC’s Influenza
Vaccine Effectiveness Network, said he was perplexed by the low
overall VE in the study, given the approximate 60 percent protection
levels found in studies by the network the same season.

The researchers used a prospective cohort design in an effort to
detect all flu cases in the study group, regardless of whether or not
participants were sick enough to seek medical attention. The team
sought to recruit households that had at least four members with at
least two children and that received medical care through the
University of Michigan Health System, based in Ann Arbor. Out of a
target group of 4511 households, the authors recruited 328, with 1441
members. Participants were instructed to report any acute respiratory
illnesses throughout the flu season. Individuals with symptoms went to
a study site for collection of a throat swab for flu testing. The
researchers followed the illnesses to collect data on disease course,
including whether the volunteers sought medical attention. Specimens
were tested using polymerase chain reaction (PCR). Among the 1441
participants, 866 (60 percent) had documentation of receiving a flu
shot for the 2010-11 season, with coverage lower among younger adults
and higher in those with high-risk health conditions. Of those
vaccinated, 88 percent received an inactivated vaccine and 12 percent
the live-attenuated vaccine. During the season, 624 individuals
reported 1028 acute respiratory illnesses, leading to the collection
of 983 specimens. Of those, 130 specimens from 125 participants (13
percent) were positive for influenza virus. By subtype, 45 percent
were influenza A/H3N2, 34 percent were type B, and 20 percent were
2009 H1N1. 32 percent of the cases led to medical attention. Among the
125 people who tested positive for flu, 59 percent had been vaccinated
at least 14 days before their illness onset, long enough for an immune
response. The infection risk in the vaccinated people was 8.5 percent
(74 of 866), versus 8.9 percent (51 of 575) in the unvaccinated
individuals.

The researchers estimated VE separately for community and household
exposures. 97 flu cases were classified as community-acquired and
included in the analysis. After adjustments for age and high-risk
medical conditions, the all-ages VE was estimated at a nonsignificant
31 percent, (95 percent confidence interval [CI], = 967 percent to 55
percent). VE estimates by age-group were similar and likewise
nonsignificant. The result was very different when the team stratified
the participants according to whether they’d had a flu immunization
the previous season. As noted above, estimated VE in those with no
prior-year immunization was 62 percent overall (95 percent CI, 17
percent to 82 percent), whereas VE in those who did get vaccinated the
year before was low in all age-groups and came out to 45 percent
overall (95 percent CI, 26 percent to 35 percent). The team defined a
household-acquired case as one that occurred within a week after
another case of the same subtype in the same household. On this basis
they determined that 30 flu cases were household-acquired. The
estimated VE for this group was 51 percent overall (95 percent CI, 54
to 36 percent), and the age-group estimates were all low.

“Adults were at particular risk of infection despite vaccination,” the
report says. “In fact, 9 of 11 (82 percent) adults with household
acquired influenza were vaccinated, compared with 11 of 19 (58
percent) children.” In this group the team found no major differences
related to prior-season vaccination. The authors found that the flu
risks were similar for adults who were vaccinated in both years and
those who weren’t vaccinated in either year. The pattern was slightly
different in children under 9 years old, in that those with no
vaccination either year had the highest risk of infection.

Summing up, the report notes that VE estimates against
community-acquired flu of all severities were all less than 40 percent
and “not statistically different than zero” (because of confidence
intervals that overlapped zero). “This unexpected finding was seen in
a season with circulation of influenza strains that were considered
matched to vaccine strains, and where evaluation of vaccine
effectiveness using case-control designs indicated significant
reductions of 52 to 60 percent in medically attended influenza
outcomes in vaccinated patients of all ages.”

Arnold Monto said possible explanations for the low VE within
households include that the vaccine may be “overwhelmed” by continual
exposure to an infected family member, particularly since children
shed more virus than adults. He said his team is working on further
studies of flu VE in the community and households and is collecting
blood samples to examine immune responses to vaccination and
infection, a step that was not possible in the current study. That may
help shed some light on the unexpected findings, he said. For now, “We
can only speculate about what’s really going on from an immunology
standpoint.” Monto commented that the study raises tough questions.
“We recommend vaccination every year because we know the duration of
protection is relatively short. What are we to do if we know that
being vaccinated every year is perhaps not the best way to get good
vaccine effectiveness?” he said.

Angus Nicoll, MB, director of the influenza program at the European
Centre for Disease Prevention and Control in Stockholm, praised the
study and said the question of prior-year vaccination clearly needs
more investigation. “Our bottom line is that immunization is the most
effective single thing you can do to protect yourself [from flu], and
this isn’t going to change what we say,” Nicoll said. But he added,
“It’s an important finding, and this does now need to be looked at in
the longer term and a larger cohort.” He commented that the question
calls for study in a stable community where the turnover of residents
is not too high.

The study also won praise from Belongia, who has studied flu VE
extensively at the Marshfield Clinic Research Foundation in Wisconsin.
“I think they did a fine job with the study,” he said. “I applaud them
for trying to do a community-based study, which is hard to do these
days.” He agreed that the finding of an effect of prior-year
vaccination is important. “It needs to be looked at in other
populations and seasons,” he said. “The numbers are relatively small
in this study. As the authors note, the majority of people who get the
vaccine get it year after year, so there may be important differences
between those who get vaccinated repeatedly and those who just
recently chose to do it.” As noted above, Belongia was particularly
puzzled that the overall adjusted VE in the Ohmit study, at 31
percent, was only about half what was found in case-control studies
the same season. “I think a key message is that we need more
community-based studies, with PCR-confirmed outcomes,” he said.

Another flu vaccine researcher, Heath Kelly, of the Victoria
Infectious Diseases Reference Laboratory in Melbourne, Australia, said
the suggestion that prior-year vaccination affects flu VE is not new,
pointing to a study of British children in 1979. He noted that another
research group developed a model suggesting that this effect is
related to the antigenic distance between the current and previous
vaccines and the circulating viruses. Kelly said he found it
“intriguing” that the Michigan study failed to find a significant
protective effect of vaccination, “given that many observational
studies in Europe, Canada, and the US found moderate protection
against medically attended, PCR-confirmed influenza in the 2010-11
season.” He remarked that the 62 percent effectiveness seen in those
who were not vaccinated the previous year is similar to other
published estimates, mainly from sentinel surveillance programs.
“Although it seems unlikely, could it be that the sentinel schemes
include a majority of people who were not previously vaccinated?” he
asked.

Another flu expert, Michael T Osteholm, PhD, MPH, said the findings
further complicate the already difficult challenge of framing flu
vaccination recommendations. “We’re at a major crossroads in
integrating our current influenza vaccine science with our current flu
vaccine recommendations,” he said. “The issues of vaccine efficacy by
age and by vaccine [formulation] as well as the concept of waning
immunity in a given season, the lack of correlation between vaccine
virus match with circulating viruses and protection, and the potential
for repeated annual vaccination to lower one’s protection, versus not
being repeatedly vaccinated, are all immense challenges for us today.
“If we don’t go back and revisit our current vaccine recommendations,
I think we stand to lose a great deal of credibility with both the
medical community and even the general public as to the
trustworthiness of what public health concludes and promotes,” he
said. “This is exactly why we need game-changing influenza vaccines.”

[Byline: Robert Roos]

– —
Communicated by:
ProMED-mail Rapporteur Mary Marshall

[Irrespective of these data influenza vaccines remain the best tool
currently available for preventing or moderating influenza-like
illness. The report above highlights the need to develop more
effective vaccines and vaccination strategies. Influenza is a seasonal
illness and more effort may need to be directed towards identifying
the roles of the many other respiratory viruses which accompany
seasonal influenza epidemics and may modify the disease response. –
Mod.CP]

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