Influenza Vaccination and Pneumonia Risk Among Older Adults

Abstract

Annual influenza epidemics that cause respiratory deaths are common all over the world. As people’s immune system becomes weaker with age, older adults face serious influenza complications more often than younger individuals. Research has shown that vaccination against the virus reduces the severity of illness in people 65 and older. The paper provides an overview of six scientific articles that deal with aspects of immunization’s effect on older adults in the U.S., Australia, and Japan. The research findings have demonstrated the efficacy of several vaccine types, such as a 13-valent pneumococcal conjugate vaccine, a high-dose vaccine, and a recombinant one. Furthermore, older adults with associated chronic conditions are more likely to acquire severe complications, for example, pneumonia. Advanced practice nurses have to rely on scientific evidence to provide older patients with adequate immunization therapy. Their role is to educate and guide individuals, highlighting vaccination benefits.

Introduction

Seasonal influenza is a respiratory infection caused by several types of viruses that are present all over the globe. It is associated with fever, dry cough, muscle pain, and sore throat. Most people tend to recover from these symptoms within a week or two without medical assistance. However, people at high risk can develop severe illnesses, including pneumonia, leading to death. Annual epidemics lead to about 290 000 to 650 000 respiratory deaths worldwide (World Health Organization, 2018). Pregnant women, individuals with chronic diseases, and people older than 65, and individuals with immunosuppressive conditions are at risk (World Health Organization, 2018). People over 65 have a weaker immune system compared with young and healthy adults and are prone to have pneumonia in the absence of vaccination. It is estimated that in the United States, between 70 and 80 percent of influenza-related deaths happen among older adults (Centers for Disease Control and Prevention, 2019). The role of advanced nursing practice is to educate patients on the importance of immunization. Annual vaccination for the elderly is an essential tool to control the spread of the disease and its fatal consequences.

Methodological Approach

The PubMed administered by the U.S. National Institutes of Health’s National Library of Medicine is the core database that contains biomedical research publications. The search, using ‘older adults, risk of pneumonia, vaccine’ keywords, brings ten results for the period from 2015 to 2020. The search with the keywords’ older adults, influenza, vaccine’ brings 59 results for the same period. I have also employed the Science Direct database and Cambridge University online sources to detect relevant papers. I have chosen two RCTs, and one post-hoc analysis that is at the second level of evidence. Furthermore, I have reviewed two prospective cohort studies and one retrospective cohort study, which can be referred to as the fourth level of evidence (Melnyk & Fineout-Overholt, 2011). The articles have been selected based on the credibility of Vaccine, The New England Journal of Medicine, BMC Geriatrics, and Epidemiology and Infection journals. The listed journals are either in the first or second quartile on the topic of infectious disease.

Review of Selected Literature

The paper by Suaya et al. (2018) presents a post-hoc analysis that evaluates the efficacy of the 13-valent pneumococcal conjugate vaccine (PCV13) in adults older than 65 years. The researchers used data from the Community-Acquired Pneumonia Immunization Trial in Adults (CAPiTA). It was a randomized, double-blind clinical study of 84 496 older adults undertaken in the Netherlands. One group of participants received PCV13, another placebo, from September 2008 to January 2010. The purpose of the CAPiTA was to prove the PCV13 efficiency against vaccine-serotype community-acquired pneumonia (VT-CAP). This research corresponds to the second level of evidence because the authors have collected data from CAPiTA RCT.

The authors of the study assessed the PCV13 efficiency, a dependent variable, for at-risk participants who had reported asthma, diabetes, smoking, heart, lung disease, and liver malfunction which are independent variables. Of all the adults in the study, 41 385 or 49.2% were at risk according to the above-mentioned medical conditions. Out of 139 VT-CAP cases, 115 happened to individuals in this group. Vaccine efficacy for those who got PCV13 reached 40.3% during the whole follow-up period of 3.95 years. Overall, this analysis shows a statistically significant measurement of the vaccine potency compared with the placebo. However, the study’s limitation is that participants have not been categorized by risk status before the initial clinical trial.

Efficacy of Recombinant Influenza Vaccine

The clinical trial by Dunkle et al. (2017) provides a comparison between a recombinant influenza vaccine (RIV4) with a standard-dose, inactivated influenza vaccine (IIV4). The research corresponds to the second level of evidence as it is a well-designed RCT. The trial covered the 2014-2015 influenza season, which had demonstrated reduced effectiveness of licensed vaccines for the A/H3N2 virus type. This randomized, double-blind, multicenter trial included 9003 participants who did not have a clinically significant illness and did not receive immunosuppressive therapy. The study considered reverse-transcriptase polymerase-chain-reaction (RT-PCR)-confirmed influenza as a dependent variable. The authors of the study employed computer-generated block randomization to assign the RIV4 or IIV4 vaccine. Participants had to report symptoms as per the protocol, regardless of severity.

The researchers put forward a primary hypothesis that the efficacy of RIV4 would not be inferior in relation to the one of IIV4. During the randomization process, 4498 participants were assigned to RIV4, and 4505 were assigned to IIV4. The study results showed that the influenza attack for both groups was similar; however, the probability of suffering from influenza was 30% lower with the RIV4 vaccine. Therefore, the authors of the study supported the initial hypothesis with evidence. Dunkle et al. (2017) highlight that research results may lack precision due to the limited number of participants. In addition, the variety of influenza types requires continuous investigation of vaccine efficacy.

High-Dose and Standard-Dose Inactivated Influenza Vaccines

Influenza exacerbates pre-existing medical conditions in adults older than 65 years. DiazGranados et al. (2015), referring to the results of the National Hospital Discharge Survey, underline that pneumonia is one of the leading causes of hospitalization in older adults. The team of researchers highlights that it is essential to assess the impact of the influenza vaccine on the number of cardio-respiratory events, taken as a dependent variable. The paper presents the results of an RCT of high-dose and standard-dose inactivated a vaccine that adheres to the second level of evidence. The authors carried out a randomized, double-blind, active-controlled, and multicenter clinical trial. It covered the 2011-2012 and 2012-2013 influenza seasons in 126 research centers across Canada and the United States. The study enrolled 31 989 participants who were divided into two groups (DiazGranados et al., 2015). The first group of 15 991 people received the IIV-HD vaccine, the second one with the remaining 15 998 got an IIV-SD shot. All the participants went through a 6-8 month post-vaccination follow-up to track the influenza occurrence and serious adverse events.

The study has a well-balanced demographic characteristic with a mean age of 73.3 in both groups. There were all-cause 3173 hospitalization events, and 948 cardio-respiratory events possibly related to influenza. Even though the rates of all-cause hospitalization events were similar for two groups during the first season, they were lower for the IIV-HD one during the second year. The IIV-HD group demonstrated significantly lower rates of serious pneumonia and congestive heart failures. Overall, the high-dose vaccine reduced the possibility of cardiorespiratory events in the second year and combined two periods. However, researchers note that the interpretation of results needs to account for the differences in the epidemiology of the two influenza seasons. The first year of the study was marked by very low influenza activity, whereas the second year coincided with a high one.

Community-Acquired Pneumonia Hospitalization: the Case of Australia

Dirmesropian et al. (2019) explore community-acquired pneumonia (CAP) related to the streptococcal infection that is a frequent cause of hospitalization. They underscore that the majority of hospitalized individuals in Australia are 65 years or older. The mortality rate is estimated to be 11.1%, which increases with age and various risk factors, such as diabetes, heart disease, and smoking (Dirmesropian et al., 2019). The purpose of the study is to provide evidence-based recommendations for enhanced prevention measures, including vaccination during the influenza season. The researchers organized a population-based prospective cohort study in New South Wales, Australia which had a third level of evidence. It encompassed 267 000 participants 45 years and older at the moment of enrollment. The participants were selected from the Department of Human Services database, who reported social characteristics and health conditions through a baseline questionnaire.

Dirmesropian et al. (2019) determined the incidence rate of the first CAP hospitalization and associated deaths or case-fatality rate (CFR) as dependent variables. The authors also defined pneumococcal disease risk groups based on the Australian Immunization Handbook. All the participants were first stratified into four age groups and then according to risk factors, referred to as independent variables. The researchers found out that the incidence of CAP and invasive pneumococcal disease (IPD) increased with age and the development of any risk factor. The probability of IPD in the 65-74 age group was three times higher for those with at least one risk factor in comparison with those without any. Consequently, the CFR that followed CAP hospitalization in the same group was 6.6% compared with 5.4% in the ‘no-risk group (Dirmesropian et al., 2019). The study’s limitation is the baseline measurement of risk factors that can create bias in the obtained results.

Inactivated Influenza Vaccine against laboratory-confirmed Influenza

Influenza and pneumonia, as its severe consequence, is one of Japan’s most prominent public health concerns. It is estimated by Suzuki et al. (2018) that the mortality rate among adults 65 and older is 24 per 100,000 persons a year. The benefit of vaccines can reduce because of an age-related decline in adaptive immunity (Suzuki et al., 2018). The researchers explored the effectiveness of the trivalent inactivated influenza vaccine (IIV), an independent variable, against laboratory-confirmed influenza pneumonia in older adults. A single-center prospective cohort study at the fourth level of evidence was conducted at Kameda Medical Center (KMC), Japan. The study enrolled 1494 pneumonia patients who visited KMC from September 2011 to August 2014. It employed a multiplex polymerase chain reaction (PCR) to test patients’ sputum samples for influenza A or B type. A test-negative design determined the influenza vaccine effectiveness (IVE).

The authors of the research managed to obtain 1044 sputum samples and had to exclude 230 patients without influenza vaccination history. Consequently, 42 individuals (5%) out of 814 eligible patients were tested positive for influenza viruses A and B. Among the study sample, 65% or 525 patients had received an influenza vaccine. The researchers detected that vaccinated individuals had been diagnosed with chronic respiratory obstructive disease more frequently than unvaccinated ones. The results of the study revealed that the IVE against laboratory-confirmed influenza pneumonia was 58.3%, and even higher for patients with immunosuppressive conditions – 85.9%. Moreover, Suzuki et al. (2018) found out that IIV could also be used to prevent bacterial pneumonia associated with influenza (49.1%). However, the study is limited by the small sample size as well as a lack of documented influenza vaccination history for 230 patients.

The Relative Burden of Community-Acquired Pneumonia in the U.S.

Although CAP influences morbidity and mortality among older individuals, the burden of illness has not been adequately assessed. Brown, Harnett, Chambers, and Sato (2018) indicate that around 40% of CAP events lead to hospitalization with an annual aggregate economic burden of $13 billion. The researchers claim that myocardial infarction (MI), stroke, and osteoporotic fractures (OF) are the core targets for prevention measures (Brown et al., 2018). The study is to compare CAP hospitalization’s relative burden, as a core dependent variable, to the ones caused by MI, stroke, and OF. Brown et al. (2018) conducted a retrospective cohort study at the fourth level of evidence that extracted data from Optum’s Clinformatics Data Mart (CDM). It included 1 949 352 participants 65-89 years old enrolled in Medicare Advantage with Prescription Drug Plan from January 1, 2014, through December 31, 2015 (Brown et al., 2018). The research divided individuals into five age groups and included hospitalization for CAP and three other causes that occurred during the 2015 calendar year.

The most common morbid conditions were diabetes, chronic pulmonary disease, coronary artery disease, and renal disease (Brown et al., 2018). The authors found out that there were a total of 16 430 CAP hospitalizations during 2015. At the same time, there were 7859 hospitalizations for MI, 5412 hospitalizations for stroke, and 6674 hospitalizations for OF (Brown et al., 2018). As a result, the total cost of the CAP hospitalization was significantly higher than that of MI, stroke, and OF. The authors highlighted that insurers had spent $830 million for MI, stroke, and OF prevention care and only $26.1 million on annual influenza vaccination. Therefore, pneumococcal and influenza vaccination of older adults should be a top priority for cost-efficient prevention care. The study is limited by the quality of data retrieved from a single CDM database, which hinders the generalization of the results.

Conclusion and Recommendations

Literature review on the topic of vaccination and pneumonia risk among older adults allows making a conclusion on vaccines’ efficiency. First of all, the 13-valent pneumococcal conjugate vaccine helps prevent VT-CAP for elderly individuals with high-risk factors. Furthermore, the research results by Dunkle et al. (2017) proved that a recombinant influenza vaccine had reduced the probability of suffering from influenza by 30% compared with an inactivated influenza vaccine. The study by DiazGranados et al. (2015) compares the high-dose and standard-dose inactivated vaccines during two seasons. The high-dose one demonstrated the possibility to eliminate the number of cardiorespiratory events during both seasons. The research paper by Dirmesropian et al. (2019) underscores that diabetes, heart disease, smoking, and alcoholism increase the risk of suffering from CAP and IPD among older Australians. The study conducted in Japan by Suzuki et al. (2018) showed that the IIV vaccine was adequate for the prevention of laboratory-confirmed influenza pneumonia. Finally, Brown et al. (2018) managed to support the claim that pneumococcal and influenza vaccination of older adults could ensure cost-efficient prevention care.

The most common limitations are the quality of data extracted from medical databases, small samples, and baseline measurements of specific factors, such as health conditions. Despite these limitations, it is clear that immunization efforts should target older adults who are prone to suffer from influenza outcomes. Therefore, advanced nursing practitioners must acknowledge the importance of early vaccination. However, since various vaccines’ efficiency differs, it is vital to use up-to-date information to make evidence-based decisions. Knowing the impact of chronic medical disorders, including diabetes, heart failures, or chronic obstructive pulmonary disease, will provide an opportunity to assist adults in risk groups. Nursing professionals need to recommend, prescribe, and administer immunization interventions as part of a health promotion strategy (Weinmayr, Steinhäuser, Gehring & Goetz, 2019). Finally, a constructive dialogue between a nurse and a patient will ensure consistent vaccination and necessary follow-up.

References

Brown, J.D., Harnett, J., Chambers, R., & Sato, R. (2018). The relative burden of community-acquired pneumonia hospitalizations in older adults: A retrospective observational study in the United States. BMC Geriatrics, 18(92).

Centers for Disease Control and Prevention. (2019). People 65 years and older & influenza

DiazGranados, C. A., Robertson, C. A., Talbot, H. K., Landolfi, V., Dunning, A. J., & Greenberg, D. P. (2015). Prevention of serious events in adults 65 years of age or older: A comparison between high-dose and standard-dose inactivated influenza vaccines. Vaccine, 33(38), 4988–4993.

Dirmesropian, S., Liu, B., Wood, J., MacIntyre, C., McIntyre, P., Karki, S., & Newall, A. (2019). Pneumonia hospitalisation and case-fatality rates in older Australians with and without risk factors for pneumococcal disease: Implications for vaccine policy. Epidemiology and Infection, 147(118).

Dunkle, L. M., Izikson, R., Patriarca, P., Goldenthal, K. L., Muse, D., Callahan, J., & PSC12 Study Team (2017). Efficacy of recombinant influenza vaccine in adults 50 years of age or older. The New England journal of medicine, 376(25), 2427–2436.

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Suaya, J. A., Jiang, Q., Scott, D. A., Gruber, W. C., Webber, C., Schmoele-Thoma, B., & Isturiz, R. E. (2018). Post-hoc analysis of the efficacy of the 13-valent pneumococcal conjugate vaccine against vaccine-type community-acquired pneumonia in at-risk older adults. Vaccine, 36(11), 1477–1483.

Suzuki, M., Katsurada, N., NhatLe, M., Kaneko, N., Yaegashi, M., Hosokawa, N., & Morimoto, K. (2018). Effectiveness of inactivated influenza vaccine against laboratory-confirmed influenza pneumonia among adults aged ≥65 years in Japan. Vaccine, 36(21), 2960-2967.

Weinmayr, L. M., Steinhäuser, J., Gehring, S. C., & Goetz, K. (2019). Vaccination management for elderly patients in primary care settings – documentation and responsibilities during a vaccination campaign. Patient preference and adherence, 13, 1295–1302.

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