A surreal illustration representing the changing landscape of adult pneumonia and the role of vaccination.

Adults and Pneumonia: What You Need to Know About the Changing Risks

Lena Kashyap in Health & Wellness December 2025 • 4 min read.

"New research from Japan reveals how childhood vaccinations are impacting adult pneumonia risks, highlighting emerging threats and the importance of adult vaccinations."

Pneumonia poses a significant health threat to adults, especially those over 65 or with underlying health conditions. While effective treatments exist, the bacteria Streptococcus pneumoniae, a major cause of invasive pneumococcal diseases (IPDs), is constantly evolving. This evolution, spurred by factors like antibiotic use and widespread vaccination programs, necessitates continuous monitoring and adaptation of preventative strategies.

In Japan, the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) for children in 2010 marked a turning point in the fight against pneumonia. Subsequent changes in vaccination schedules, including the shift to PCV13, have had a cascading effect on the types of pneumococcal bacteria circulating and their resistance to drugs. Understanding these shifts is critical for protecting adult populations.

Recent research closely examined these changes, analyzing data collected from adult IPD cases in Japan between 2010 and 2013. The findings reveal a complex picture of how childhood vaccination programs are indirectly influencing adult health, with some positive outcomes alongside the emergence of new challenges.

The Impact of Childhood Vaccinations on Adult Pneumonia: A Shifting Landscape

A surreal illustration representing the changing landscape of adult pneumonia and the role of vaccination.

The study revealed a notable decrease in the prevalence of PCV7 serotypes among adults with IPDs, dropping from 43.3% to 23.8%. This decline was most significant for serotype 6B, a strain targeted by the vaccine. Similarly, there was a reduction in serotypes covered by the 23-valent pneumococcal polysaccharide vaccine (PPSV23), which is commonly recommended for older adults.

However, this positive trend was accompanied by a concerning rise in non-PPSV23 serotypes, increasing from 13.8% to 25.1%. These 'non-vaccine' types, not included in the common vaccines, are stepping in to fill the void left by the declining vaccine-targeted strains.

Decreased PCV7 serotypes: Good news, showing the vaccines are working.
Rise of non-PPSV23 serotypes: A concerning trend, demanding attention.
Emergence of drug-resistant strains: Making treatment more difficult.

Parallel to these serotype changes, the study also observed a decrease in genotypic penicillin-resistant S. pneumoniae, falling from 32.4% to 21.1%. Despite this encouraging sign, six non-PPSV23 serotypes (6D, 15A, 15C, 16F, 23A, and 35B) emerged, demonstrating the bacteria's adaptability and potential for developing resistance to multiple drugs.

Protecting Yourself: What These Findings Mean for Adults

The Japanese study underscores the dynamic nature of pneumonia-causing bacteria and the indirect yet significant impact of childhood vaccination programs on adult health. While PCV7 and PCV13 vaccines have proven effective in reducing the overall burden of IPDs, the emergence of non-vaccine serotypes and drug-resistant strains requires a proactive approach to adult health.

Adults, especially those 65 and older or with underlying health conditions, should discuss vaccination options with their healthcare providers. While PPSV23 offers broad coverage against many pneumococcal serotypes, it may not be effective against the emerging non-vaccine types. The potential benefits of PCV13 for adults should also be considered, particularly for those at higher risk of IPDs.

Continued surveillance and research are crucial for monitoring serotype changes and resistance patterns in S. pneumoniae. This information will inform future vaccine development and public health strategies aimed at minimizing the impact of pneumonia on adult populations worldwide.

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This article is based on research published under:

DOI-LINK: 10.3201/eid2111.142029, Alternate LINK

Title: Serotype Changes And Drug Resistance In Invasive Pneumococcal Diseases In Adults After Vaccinations In Children, Japan, 2010–2013

Subject: Infectious Diseases

Journal: Emerging Infectious Diseases

Publisher: Centers for Disease Control and Prevention (CDC)

Authors: Kimiko Ubukata, Naoko Chiba, Shigeo Hanada, Miyuki Morozumi, Takeaki Wajima, Michi Shouji, Satoshi Iwata

Published: 2015-11-01

Everything You Need To Know

How did the introduction of childhood vaccinations impact adult pneumonia risks?

The introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in 2010 in Japan aimed to reduce the prevalence of Streptococcus pneumoniae in children. This had a ripple effect, leading to a decrease in PCV7 serotypes among adults with invasive pneumococcal diseases (IPDs), showcasing the interconnectedness of vaccination efforts across age groups. Subsequent shift to PCV13, have had a cascading effect on the types of pneumococcal bacteria circulating and their resistance to drugs. Understanding these shifts is critical for protecting adult populations.

What are non-PPSV23 serotypes, and why are they a concern for adult pneumonia?

While childhood vaccination programs, particularly using PCV7 and PCV13, have been successful in decreasing the prevalence of vaccine-targeted strains like serotype 6B, there's a concerning trend: the rise of non-PPSV23 serotypes. These are strains not covered by the 23-valent pneumococcal polysaccharide vaccine (PPSV23) commonly recommended for older adults. As vaccine-targeted strains decline, these non-vaccine types are stepping in to fill the void, creating new challenges for adult health.

What did the research reveal about drug-resistant strains of Streptococcus pneumoniae?

The study found a decrease in genotypic penicillin-resistant Streptococcus pneumoniae, which is initially encouraging. However, it also highlighted the emergence of six non-PPSV23 serotypes (6D, 15A, 15C, 16F, 23A, and 35B) that exhibit drug resistance. This adaptability of the bacteria means that treatment options for pneumonia could become more limited, emphasizing the need for ongoing surveillance and development of new treatment strategies.

Why is the 23-valent pneumococcal polysaccharide vaccine (PPSV23) recommended for older adults, and how is its effectiveness changing?

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for older adults because it helps protect against 23 of the most common serotypes of Streptococcus pneumoniae. The study showed a reduction in serotypes covered by PPSV23. Although the prevalence of PCV7 serotypes decreased among adults with IPDs, there has been a rise in non-PPSV23 serotypes, potentially diminishing the overall effectiveness of PPSV23 in preventing pneumonia in adults.

What steps are needed to effectively protect adults from pneumonia, considering the changing risks?

The ongoing evolution of Streptococcus pneumoniae, driven by factors like antibiotic use and vaccination programs, requires a proactive and adaptive approach to prevention and treatment. Continuous monitoring of circulating serotypes and their resistance patterns is crucial. Further research into the effectiveness of current vaccines against emerging strains, as well as the development of new vaccines and treatment strategies, is necessary to safeguard adult populations from the evolving threat of pneumonia. Furthermore, understanding the impact of interventions such as PCV13, is crucial for informing future public health policies.