Infection Spotlight

Data Show Poor Vaccine Efficacy in Elders With Influenza Virus H3N2

The 2012-2013 influenza season in the United States started early and was more severe than previous years. The Centers for Disease Control and Prevention calculated that the rate of laboratory-confirmed influenza-associated hospitalizations for the season was 40.6 per 100,000 persons. Of these hospitalizations, 51% occurred in adults aged 65 years and older. Older adults are typically in the highest risk group of flu-related hospitalization and death every year; however, incoming data are showing that vaccine efficacy in older persons with H3N2 virus was significantly low.

According to a new study in the Journal of Infection in Developing Countries by David Kelvin and Amber Farooqui, Shantou University Medical College, China, this year’s flu vaccine displayed extremely low effectiveness against the influenza A virus (H3N2) in elders (www.ncbi.nlm.nih.gov/pubmed/23493013). The other two viruses included in this year’s flu vaccine were influenza A virus (H1N1-like virus) and an influenza B virus (2010-like virus). Across all age groups, the effectiveness of the vaccine to protect against all influenza viruses and against the H3N2 virus in particular was 56% and 47%, respectively. The vaccine was effective in only 9% of adults aged 65 years and older with the H3N2 virus, compared with 50% in adults between the ages of 50 and 64 years.

Kelvin and Farooqui speculated that the low efficacy may be attributed to antigenic changes identified in the HA1 gene of the H3N2 virus. “A simple interpretation of this data is that the elderly generate a narrow antibody response to the vaccine strain of H3N2, which is not capable of protecting against a H3N2 virus with shifted antigenicity,” they reported. Further antigenic studies may shed light on this possibility, but until these fundamental studies in the elderly are conducted, they added, these data underscore the need for vigilant real-time surveillance for shifting influenza viruses and proactive treatment of elders during influenza outbreaks.

Infection Predicts Disability in Activities of Daily Living

Adults in the oldest-old age group (>85 years) are more predisposed to infectious disease as a result of age-related physical deterioration and comorbidities. The prevalence of infection in long-term care settings is high, but little is known about the co-occurrence of incident infection and impairment in activities of daily living (ADLs). Monique Caljouw, Department of Public Health and Primary Care, Leiden University Medical Center, Netherlands, and associates recently published the results of the Leiden 85-Plus Study, a population-based prospective follow-up study that examined the link between incident infection and ADL disability in a cohort of 473 adults aged 86 years (www.ncbi.nlm.nih.gov/pubmed/23482352).

From face-to-face interviews with the study participants and medical records, the researchers compiled baseline data regarding incident urinary tract infection and incident lower respiratory tract infection; cognitive status; comorbidities; and ADL ability as measured by the Groningen Activity Restriction Scale (GARS). Information on patients’ background and ADL performance was obtained annually for 4 years. In participants with ADL disability at baseline, the researchers observed there were no differences in ADL increase between participants with and without an infection (-0.32 extra GARS points per year; P=.230). However, participants without ADL disability at baseline (n=194) had an accelerated increase in ADL disability of 1.07 extra GARS points per year (P<.001). For urinary tract infections, there was an increase of 1.25 GARS points per year (P<.001); for lower respiratory tract infection, there was an increase of 0.70 points per year (P=.041). Based on the results of their statistical analysis, the researchers concluded that in older persons without ADL disability at 86 years, clinical infection can predict the development of ADL disability from age 86 onward (hazard ratio, 1.63; 95% confidence interval, 1.04-2.55).

The study also has clinical implications for long-term care providers. The researchers concluded that healthcare providers “should be vigilant when older persons without ADL disability get infections and [should] start active functional rehabilitation to maintain independence in ADLs.” Future studies should assess whether prevention of infection, quick recovery, and functional rehabilitation can
assist the oldest-old in maintaining ADL independence and avoiding adverse health outcomes.

Study Finds Atypical Pathogens Are Not a Significant Cause of Nursing Home–Acquired Pneumonia

Atypical pathogens (APs), such as Mycoplasma pneumonia, Chlamydia pneumonia, and Legionella pneumophila have been implicated in up to 40% of cases of community-acquired pneumonia (www.aafp.org/afp/2004/0401/p1699.html). Guidelines advise empiric antibiotics to treat atypical pneumonia; however, until recently, these guidelines have not thoroughly addressed prevalence and treatment of atypical nursing home–acquired pneumonia (NHAP).

Diagnosis and management of NHAP is complex because of the high prevalence of frailty, cognitive impairment, and polypharmacy in nursing home residents. In a new study, specialists at the Division of Geriatric Medicine, Chinese University of Hong Kong, sought to investigate the prevalence and clinical characteristics of AP infections and the need for empirical antibiotics in NHAP. Ma Hon-ming and colleagues conducted a prospective cohort study involving a total of 127 nursing home residents (aged ≥65 years) who had been hospitalized for NHAP. Annals of Long-Term Care^® (ALTC) had the opportunity to interview Ma about the findings of the study, which were recently published in the Journal of the American Medical Directors Association (www.ncbi.nlm.nih.gov/pubmed/23206723).

ALTC: There is a lack of consensus data regarding empiric antibiotic therapy in patients with NHAP caused by an AP. What does your study add to the medical literature and the clinical understanding of treating NHAP?

Dr. Ma: Our study adds to the literature that APs are not an important cause of NHAP, as evidenced by the low prevalence (10.2%) and the lack of antibiotic treatment not resulting in mortality. Therefore, NHAP does not need to be treated routinely with antibiotics covering APs. Furthermore, Legionella pneumophila was not detected in our cohort, confirming its rarity in NHAP, as found in previous studies.

In your study, 12 APs were detected in 11 patients, the most common of which were Mycoplasma pneumonia and Chlamydia pneumonia. None of the 11 patients received antibiotics indicated for atypical infection; however, you noted that AP infections did not result in mortality. Were you and your colleagues surprised by this finding?

It is intriguing that NHAP caused by APs does not lead to any mortality even in the absence of appropriate antibiotic treatment. We believe that APs, like the majority of respiratory viruses, cause influenza-like illness and pneumonia of milder severity. Their clinical courses are usually self-limiting. Antibiotics with atypical coverage should be added empirically if patients do not respond to beta-lactam antibiotics or develop severe pneumonia.

What is the next step of research in the area of preventing and treating NHAP?

The importance of dental hygiene and mouth care is the focus of future research in preventing NHAP. Besides, it is controversial if NHAP should be treated according to the community-acquired pneumonia or healthcare-associated pneumonia guidelines because of the increasing prevalence of drug-resistant pathogens. We believe that risk stratification is the best approach to guide clinicians in choosing appropriate empirical antibiotics for NHAP. Future work is directed at identifying the most significant risk factors for resistant organisms in NHAP.

New App Allows Year-Round Influenza Monitoring

Although the influenza season tends to peak in January and February, flu activity can begin as early as October and linger well into May. To help clinicians stay up-to-date with national flu activity year-round, the Centers for Disease Control and Prevention (CDC) has created a new application for the iPad, iPhone, and iPod Touch. The app enables instant access to vaccination recommendations from the CDC and the Advisory Committee on Immunization Practices for healthcare providers working in any care setting. The app’s database includes information on diagnosis and treatment of influenza, including laboratory testing and antiviral treatment recommendations. Users can individualize the app to their needs with features such as highlighting, notes, and bookmarks. Free resources can be downloaded from the app for office use or distribution to patients. The app is available for free from the iTunes App Store. Download it at https://itunes.apple.com/us/app/cdc-influenza-flu/id577782055.