Although considered nonserious, adverse events (AEs) following pneumococcal vaccination occurred predominantly during the first 30 days after administration, according to a study published in Frontiers in Cellular and Infection Microbiology.1 The main safety concerns identified included injection site reactions, erythema, crying, swelling, skin warmth, and cellulitis.
“The rising incidence of antimicrobial-resistant bacterial variants has led to significant reductions in the clinical effectiveness of existing antibiotic regimens, necessitating the development of novel treatment approaches,” wrote the authors of the study. “Concurrently, large-scale implementation of vaccination programs has been identified as an essential component in addressing this global health challenge.”
Streptococcus pneumoniae remains a leading cause of mortality across all countries and age groups throughout the globe.1 Despite these mortality risks and the annual rates of S. pneumoniae reaching nearly 1 million adults, the National Foundation for Infectious Diseases reports that 46% of high-risk patients are unaware of pneumococcal disease.2
Researchers focused on adverse events from vaccination, a specific aspect of pneumococcal vaccine uptake and the reasons in which patients may be hesitant to receive one. | image credit: Kamitana / stock.adobe.com
On top of this prominent lack of awareness regarding the virus, patients with antimicrobial resistance have led researchers to further develop pneumococcal vaccines with higher valencies than before. Furthermore, with the S. pneumoniae pathogen accounting for significantly increased risks among pediatric patients as well as adults, the structured development of pneumococcal vaccines has been a must in various patient populations requiring different needs.1
READ MORE: Capvaxive Shows Immune Responses to All 21 Serotypes for Children, Adolescents
“PCVs have been integrated into national childhood immunization programs worldwide,” wrote the authors of a study published in Pneumonia.3 “Nevertheless, despite the success of PCVs [pneumococcal conjugate vaccines] in reducing pneumococcal carriage and invasive disease, particularly in children, as well as in high-risk adults, acquisition of a broadly serotype-independent vaccine remains the ‘holy grail’ of pneumococcal vaccine development, albeit a challenging and difficult endeavor.”
Pneumococcal conjugate vaccines, or PCVs, are 1 of 2 types of pneumococcal vaccines available for patients in the US, along with pneumococcal polysaccharide vaccines (PPSVs). While the 13-valent PCV (PCV13) has shown significantly successful results in protecting children and older adults against pneumococcal disease, researchers have been developing PCV15, PCV20, and PCV21 as the need for higher valencies and protection against various serotypes arises.4
Researchers conducting the current study, however, wanted to focus on a specific aspect of pneumococcal vaccine uptake and the reasons why patients may be hesitant to receive one: potential AEs.
“Our study employs comprehensive data mining of [vaccine adverse event reporting system] (VAERS) reports across multiple pneumococcal vaccine formulations to systematically characterize post-vaccination safety profiles, thereby establishing evidence-based risk stratification to inform clinical vaccination strategies,” they wrote.1
As part of the study, researchers explored the VAERS database for all AEs in conjunction with reports of pneumococcal vaccines from January 1990 to March 2025. To further understand the severity and prominence of pneumococcal AEs, researchers also used the European Medicines Agency’s 62 preferred term codes to categorize designated medical events (DMEs) throughout the study period.
Among a total of 157,244 patients (54.29% women, 38.2% under the age of 18) receiving the pneumococcal vaccine included in the study, there were 632,481 AEs detected. For all study participants with documented clinical outcomes, the most common were complete recovery (44.2%) and hospitalization due to AEs (14.94%).
Furthermore, highlighting researchers’ key study finding, 77.11% of participants experienced AEs during the first 30 days after receiving a pneumococcal vaccine. The mean time it took for patients to develop AEs was 4.2 days, with a median onset of 0 days.
“To our knowledge, this pharmacovigilance study is the first to comprehensively integrate safety signals across multiple pneumococcal vaccines using the US VAERS database,” continued the authors.1 “This study assessed post-licensure pneumococcal vaccines’ safety using VAERS database disproportionality assessments and DME list monitoring. It is noteworthy that this study observed 77.11% of AE reports clustering within the 0- to 30-day window following pneumococcal vaccination.”
As researchers have previously mentioned, the development of pneumococcal vaccines has presented a variety of challenges and complexities due to the sheer variance in patient populations that require protection against the disease. While the “holy grail” of pneumococcal vaccines has yet to be identified, studies like this will continue to inform the development of these vaccines and the necessary pharmacovigilance of future investigations.
“The majority of AEs occurred within the initial 30-day post-vaccination period,” they concluded.1 “These findings offer critical insights for clinical safety surveillance of pneumococcal vaccines and inform decision-making by regulatory agencies and health care professionals regarding risk mitigation strategies.”
READ MORE: Pneumococcal Resource Center
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