Pneumococcal Serotype Can Determine Clinical Disease Outcomes
Invasive pneumococcal disease is a cause of morbidity and mortality in the US, despite the availability of vaccination against the disease.
Patients with invasive pneumococcal disease (IPD) serotypes 3, 6A, 11A, 15A, 19F, and 31 were most likely to die, with serotype 31 having the highest case fatality rate, according to results of a study published in Frontiers in Medicine.1
Invasive pneumococcal disease is a cause of morbidity and mortality in the US, despite the availability of vaccination against the disease. | Image Credit: kittisak - stock.adobe.com
“We found that the risk of death varied by serotype in IPD. Several S. pneumoniae serotypes for both vaccine and non-vaccine types are associated with an increased risk of fatal outcomes however, vaccine serotypes significantly associate the risk of death more compared to non-vaccine serotypes,” the authors of the study wrote.1
IPD is a cause of morbidity and mortality in the US, despite the availability of vaccination against the disease. In 2000, the 7-valent pneumococcal conjugate vaccine was introduced, reducing rates by 64% to 77% for adults and older children and to less than 1 case per 100000 children under 5. In 2010, after the introduction of the 13-valent pneumococcal conjugate vaccine, the rates of IPD decreased further. However, the CDC reported more than 35000 cases and 4200 deaths from IPD in 2011.2
Currently, there are 2 types of pneumococcal vaccines in the US, including conjugate vaccines and polysaccharide vaccines. The CDC suggests that vaccination is important for older adults specifically because they are at the greatest risk of serious illness or death, and vaccination can help to protect against invasive infections. Vaccination is recommended for children younger than 5 years or children 5 through 18 with certain risk factors, as well as for adults 50 years and older and adults aged 19 through 49 with certain risk factors, according to the CDC.3
Investigators of the current study aimed to determine if the risk of death or mortality associated with specific serotypes could help predict IPD outcomes and inform better treatment decisions. In the systemic review and meta-analysis, investigators assessed the serotype-specific risk of death due to IPD and confirmed if the risk of death is a stable serotype-associated property. The authors included available studies on IPD and pneumococcal serotype case fatalities from 2010 to date. A literary search between October 17 and October 28, 2024, was conducted.1
A total of 45 studies from 5 geographical regions were analyzed, with 23 being from Europe, 8 from Asia, and 7 from North America. There were only 4 studies from Africa and 3 from South and Central America. Of those, 16 were included in the meta-analysis, with 8 representing adults and 2 representing pediatrics. The other 6 studies focused on all age groups.
Investigators identified the serotypes more likely to cause mortality, which included 3, 6A, 11A, 15A, 19F, and 31. Further, they identified serotypes 1, 5, 7F, and 8 as least likely to cause mortality.1
The case fatality rates were highest for serotypes 31 at 31.4% and 11A at 30.1%. Serotypes 6A and 19F had case fatality rates of 29.7% and 28.6%, respectively. As for the lowest serotypes, 33F, 5, 7F, and 1 had the lowest at 12.8%, 12.7%, 12.4%, and 9.9%, respectively. The pooled relative risk for vaccine serotypes was 1.36 compared with nonvaccine serotypes at 1.019, which indicated a higher risk of death with the vaccine serotypes, according to the investigators.1
“Expanding vaccine coverage to include additional serotypes could further reduce the overall burden of pneumococcal disease. Our crucial finding about risk of death for some NVTs [nonvaccine serotype] is vital to inform their inclusion recent higher-valent formulations,” the study authors said.1 “Acknowledging that epidemiological data is key in selecting vaccine serotypes, our results, as well as the individual studies included provide enough evidence to consider incorporating serotype 31, and 15A into vaccine formulations.”
READ MORE: Pneumococcal Resource Center
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