Pneumococcal Disease Concerns Remain Despite Successful Vaccine Introduction
Researchers wanted to understand the distribution of pneumococcal conjugate vaccine serotypes and how they have potential to impact pneumococcal disease severity and burden.
Concerns remain surrounding the burden of pneumococcal diseases despite the introduction of pneumococcal conjugate vaccines (PCVs) within national immunization programs, according to data published in Human Vaccines & Immunotherapeutics.1
“Streptococcus pneumoniae is one of the major pathogens of human diseases,” wrote authors of the study. “It causes both invasive pneumococcal disease (IPD), such as bacteremia and meningitis, and non-invasive pneumococcal disease (NIPD), such as non-bacteremic pneumonia. The global pneumococcal disease burden is the most marked in children aged <5 years and adults aged ≥65 years. IPD is associated with a higher mortality rate than NIPD, while the incidence of non-bacteremic pneumonia exceeds that of IPD in adults.”
According to authors of the study, streptococcus pneumoniae is known to cause both IPD and NIPD. | image credit: frinz / stock.adobe.com
The public’s defense against pneumococcal diseases originally existed in the form of the 23-valent pneumococcal polysaccharide vaccine (PPSV23), which was introduced in 1983.1 It wasn’t until the year 2000 where pneumococcal conjugate vaccines (PCVs) were first introduced to the marketplace, with the first being the 7-valent vaccine, or PCV7.2
READ MORE: Knowledge Gaps Limit Pneumococcal Vaccination in Community Pharmacies
“PCVs, which elicit a T-cell-dependent immune response, were developed, promoted by the success of Haemophilus influenzae type b vaccine,” continued the authors.1 “The first PCV, a 7-valent pneumococcal conjugate vaccine (PCV7), including serotype 4, 6 B, 9 V, 14, 18C, 19F, and 23F, was introduced in 2000 and demonstrated high-level effectiveness in children.”
Since the introduction of PCVs, higher valency has been added to previous formulations, with versions of the vaccine arising such as PCV10 and PCV13. Now, there are currently 3 PCV options for keeping patients protected against pneumococcal diseases and 1 polysaccharide alternative. The 3 PCV options include PCV21 (Capvaxive), PCV20 (Prevnar20), and PCV15 (Vaxneuvance), according to the CDC.2
Amid the development of PCVs with new serotypes, as well as variability in serotypes based on region, researchers aimed for a better grasp on serotype distribution and pneumococcal disease severity across multiple countries.1
“Herein, we discuss the serotype distribution of pneumococcal diseases in adults, including IPD and pneumococcal pneumonia, among both high-income and non-high-income countries based on the World Bank classification, and the severity of diseases caused by individual serotypes, aiming to better understand the epidemiology of pneumococcal diseases in adults and develop and implement future pneumococcal vaccines.”
Researchers conducted an exploration of PCV serotypes, which are simply groupings of cells with bacteria or viruses that cause pneumococcal diseases.3 With previous extensive knowledge into which serotypes cause which types of pneumococcal diseases, their focus was dedicated to the location of serotype surveillance across various countries.
“Although pediatric PCV immunization programs are well-established and indirect effects have been observed among adults in high-income countries, pneumococcal diseases caused by PCV13 serotypes persist among adults. Serotype 3 is one of the most common serotypes, and serotype 4 has reemerged in the Western US and Canada in specific populations,” they wrote.1
In high-income countries where PCVs were introduced across multiple immunization programs, serotypes 3 and 4 were still significantly present with the ability of increasing pneumococcal disease burden. Results in non-high-income countries were similar, with serotype 3 significantly present in both children and adults.
The key takeaway from these results, according to researchers, is to further encourage increased uptake of the PCV, especially in countries where serotype 3 is prominent.
“Pneumococcal vaccine is essential for addressing the burdens of pneumococcal disease. However, several challenges require attention,” continued the authors. “It is necessary to increase vaccination uptake among adults, particularly older adults and individuals with a high pneumococcal disease risk. Efforts should prioritize raising awareness and improving accessibility, especially for high-risk groups of people and vulnerable populations.”
While PCVs are a relatively new development in treating pneumococcal diseases, a significant amount of research has been conducted so that experts and providers can better understand the intricacies of serotypes for conjugate vaccines. With further developments in PCVs inevitable, the researchers believe better approaches to increasing vaccine uptake are crucial to protecting patients against diseases like IPD.
“The incidence of IPD cases by vaccine-covered serotypes and the serotype distribution in adults differs by country and has been changing over time, even within countries,” they concluded.1 “To determine the optimal pneumococcal vaccination strategy for adults, the latest epidemiological information on the local serotype distribution in adult pneumococcal diseases is essential. Thus, ongoing surveillance to investigate the incidence and proportion of pneumococcal diseases by serotype should be maintained, and the development of surveillance is an urgent issue in countries where surveillance systems have yet to be established.”
READ MORE: Pneumococcal Resource Center
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