Cost-Effectiveness of Pneumococcal Vaccines for Adults Aged 65 Years and Older in Argentina

Cost-Effectiveness of 20-Valent Pneumococcal Conjugate Vaccine in Argentinean Adults

INTRODUCTION

In Argentina, vaccination with 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23; PCV13 → PPSV23) has been recommended for all adults aged ≥ 65 years and younger adults with chronic medical ("moderate-risk") or immunocompromising ("high-risk") conditions since 2017. With the approval of a 20-valent PCV (PCV20), we evaluated the cost-effectiveness of PCV20 versus current recommendations for moderate-/high-risk adults aged 18-64 years and all adults 65-99 years.

METHODS

A probabilistic cohort model was used to project lifetime outcomes and costs associated with invasive pneumococcal disease (IPD) and all-cause non-bacteremic pneumonia (NBP), and the expected impact of vaccination. Clinical outcomes were projected annually based on Argentinean data. Economic costs were estimated based on cases and corresponding medical costs (adjusted to 2023 USD) and costs of vaccine and administration. Cost-effectiveness of PCV20 was evaluated versus the current strategy, PCV13 → PPSV23, and alternatively, versus sequentially administered 15-valent PCV and PPSV23 (PCV15 →  PPSV23), and presented as cost per quality-adjusted life year gained; a healthcare system perspective was used. Costs and benefits were discounted at 3%/year.

RESULTS

PCV20 in lieu of PCV13 → PPSV23 among moderate-/high-risk adults aged 18-64 years and all adults 65-99 years (N = 13.4M) prevented 3838 IPD, 4377 inpatient NBP, and 6003 outpatient NBP cases, and 1865 disease-related deaths; relative to PCV15 → PPSV23 the corresponding reductions were 2775, 3285, 4518, and 1348. PCV20 was projected to be the dominant strategy versus PCV13 → PPSV23 and PCV15 → PPSV23 as overall costs were lower by $87.6M and $80.8M, respectively. In probabilistic sensitivity analyses, PCV20 was dominant (i.e., more effective, less costly) in 100% of 1000 simulations.

CONCLUSIONS

Analyses suggest implementing a PCV20 vaccination program in moderate-/high-risk adults aged 18-64 years and all adults ≥ 65 years-in lieu of PCV13 → PPSV23-would yield substantial reductions in pneumococcal disease and would be cost saving to the Argentinean healthcare system.

Herd immunity in older adults from a middle-income country: A time-series trend analysis of community-acquired pneumonia mortality 2003-2017

Background and Aims

Community-acquired pneumonia is responsible for substantial mortality, and pneumococcus is commonly accepted as a major cause of pneumonia, regardless of laboratory confirmation. Child immunization programs have reported success in decreasing pneumonia mortality: directly in young children and indirectly (herd immunity) in unvaccinated adult populations in some countries. We assess changes in mortality trends for all-cause pneumonia in older adults associated with the introduction of pneumococcal vaccination for children in Peru.

Methods

This is a secondary analysis on administrative data collected periodically by the Peruvian Ministry of Health. An observational retrospective time series analysis was conducted using longitudinal population-based data from death certificates in Peru between 2003 and 2017. The time series includes 6 years before and 9 years after the introduction of the pneumococcal-conjugated vaccines in the national child immunization program in 2009. Monthly frequencies and annual rates for all-cause pneumonia deaths in children under 5 years of age and adults over 65 years of age are presented. Linear and quadratic trends are analyzed.

Results

Deaths among older adults accounted for 75.6% of all-cause pneumonia mortality in Peru, with 94.4% of these reporting "pneumonia due to unspecified organism" as the underlying cause of death. Comparing pre- and post-child immunization program periods, annual average mortality rates from unspecified pneumonia decreased by 22.7% in young children but increased by 19.6% in older adults. A linear trend model supports this overall tendency, but a quadratic curve explains the data better.

Conclusion

Pneumococcal-conjugated vaccines are developed using serotypes prevalent in selected countries from less common (invasive) pneumococcal disease and expected to prevent mortality worldwide from widespread (noninvasive) pneumonia. Our results do not support the presence of herd immunity from pneumococcal vaccination of children for community-acquired pneumonia in the increasingly ageing population of Peru. This should direct future research and could influence public health policy.

A Lower Level of Post-Vaccinal Antibody Titer against Influenza Virus A H1N1 May Protect Patients with Autoimmune Rheumatic Diseases from Respiratory Viral Infections

Background and Objectives: The concentration of antibodies against virus influenza A H1N1 in the titer (≥1:32) positively correlates with resistance to flu in healthy persons. In elderly and immune-compromised patients, an influenza vaccine may be less immunogenic. Hypothesis: A lower post-vaccinal antibody titer (≥1:16) may be sero-protective against respiratory viral infections in patients with autoimmune rheumatic diseases. Materials and Methods: Fifty patients with autoimmune rheumatic diseases (Systemic Lupus Erythematosus—24; Rheumatoid Arthritis—15; and Sjögren’s Syndrome—11), who were at least 65 years old or whose relative disease duration (disease duration/age) was greater than 1/8, were examined. Thirty-four of them were vaccinated with a trivalent inactivated non-adjuvant influenza vaccine. The antibody concentration against influenza virus A H1N1 was measured using the standardized hemagglutination inhibition test and patients who got any respiratory viral infection were registered. To test the hypothesis, a correlative analysis was applied, followed by a binary logistic regression that included potential confounding variables, such as age, disease duration and therapy (personal/health-related conditions). Results: Vaccinated patients were significantly less affected by respiratory viral infections (21% vs. 75%). The lower titer considered (≥1:16) was significantly present more often among vaccinated patients (68% vs. 6%). The correlation between its presence/absence and that of respiratory viral infections was –0.34 (p < 0.05). The binary logistic regression evidenced the relevance of this correlation, confirming the hypothesis. Vaccination was associated with the 87.3% reduction in the likelihood of getting respiratory viral infections, whereas the lower antibody titer (≥1:16) was associated with the 77.6% reduction in the likelihood of getting respiratory viral infections. The vaccine was well tolerated by all patients and after vaccination no exacerbation of the underlying disease was observed. Conclusions: A lower antibody titer (≥1:16) against influenza virus A H1N1 could be protective against respiratory viral infections for certain autoimmune rheumatic diseases patients, which confirms the clinical effectiveness of influenza vaccination.