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Pneumococcal Diseases
New Data on Pneumococcal Diseases and Vaccines From ESCMID Global 2024 and ISPPD-13

Released: June 14, 2024

Expiration: June 13, 2025

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Key Takeaways
  • Pneumococcal infection rates among adults remain high and may be affected by transmission from children.
  • Pneumococcal vaccines that cover updated and expanded serotypes are key to pneumococcal disease prevention.

The burden related to pneumococcal infections among adults remains very high despite availability of pneumococcal vaccines. At the 2024 European Society of Clinical Microbiology and Infectious Diseases global congress (ESCMID Global 2024), several new studies shed light on reasons for this persistent burden as well as vaccines in development to reduce it.

At the 13th Meeting of the International Society of Pneumonia and Pneumococcal Diseases (ISPPD-13), additional data were presented on pneumococcal vaccines as well as new data that highlight strategies to increase pneumococcus vaccine coverage of children around the globe.

Low Pneumococcal Vaccine Coverage in Adults
The persistent high burden of pneumococcal infections may be related to low pneumococcal vaccine coverage in adults. In France, for instance, pneumococcal vaccine coverage is particularly low in at-risk people. Because of this, each opportunity to vaccinate should be used.

To evaluate the prevalence of missed opportunities for pneumococcal vaccination in at-risk people in France, Botelho-Nevers and colleagues conducted a retrospective review using data on at-risk adults in 2020 from the French National Health Data System. A missed opportunity to vaccinate was defined as any contact of a person eligible to be vaccinated with healthcare services that does not result in the person receiving the vaccine(s) for which they are eligible.

Of the 7,336,769 at-risk people identified, 84% had a chronic underlying disease predisposing them to pneumococcal infection and 24% were people with immunocompromise. Among this at-risk population, 6,340,958 eligible patients had received no 13-valent pneumococcal conjugate vaccine (PCV13) since 2009. Only 13.6% of all at-risk patients had received at least 1 dose of PCV13 between 2009 and 2020.

At least 1 missed opportunity for vaccination was present in 93.8% of patients with no PCV13 administered. The median number (IQR) of missed opportunities for vaccination for people with no PCV13 administered was 8 (4;13), and of those, 5 (2;8) were related to a general practitioner’s (GP’s) visit.

People with chronic underlying diseases had a higher proportion of visits with GPs compared with most other types of healthcare contact. By contrast, visits to GPs did not account for the majority of missed opportunities for vaccination for people with immunocompromise.

All healthcare professionals—whether community- or hospital-based—should be concerned with these large numbers of missed opportunities for vaccination, and action should be taken to improve vaccination when the opportunity presents itself. Further, prospective studies need to be conducted to explain the high number of missed opportunities for vaccination in France.

Dynamics of Pneumococcus Carriage Among Adults 60 Years or Older
Obtaining a better understanding of the pneumococcus transmission sources to community-dwelling older adults is crucial to reduce the burden of pneumococcal infection in this population. To evaluate the dynamics of pneumococcus acquisition in adults aged 60 years or older, a longitudinal study was conducted in New Haven, Connecticut (United States) to examine carriage household pairs (eg, married couples) in this age range, all of whom had no younger individuals living in the household.

Dr Wyllie and colleagues enrolled 183 adults (average age 70 years; 51% female; 85% White) living in 93 households over the course of autumn/winter 2020/2021 and 2021/2022. Saliva samples and data from questionnaires about social behaviors and health were collected from participants every 2 weeks over 6 visits for 10 weeks. Samples were tested by quantitative PCR for the presence of pneumococcus DNA and for the diversity of pneumococcal strains. They found that pneumococcal carriage at any sampled time was 6 times higher among older adults who had contact with children daily or every few days compared to older adults who had no contact with children (10% vs 1.6%).

The researchers found no clear evidence of adult-to-adult pneumococcus transmission even though there were households in which 1 individual was positive for pneumococcus on multiple samples. Pneumococcus transmission was highest in older adults who had frequent contact with children.

Based on these findings, researchers concluded that pneumococcus vaccination of adults aged 60 years or older may be needed to protect them, even in countries like the United States where childhood pneumococcal vaccination rates are high.

Increasing Global Pneumococcal Vaccination in Children
The high cost of pneumococcal conjugate vaccines (PCV) results in only 6 out of 10 children being protected against pneumococcal disease. To improve this coverage, Gavi, the Vaccine Alliance, supports low-income countries in being able to afford the vaccine. However, not every country is eligible for this support, and many that do not qualify still cite cost as a barrier to providing this vaccine.

A dose-reduction strategy has been tested in high-, middle-, and low-income countries. Evidence on the effectiveness of reducing the dosing schedule from 3 or 4 doses to 2 doses holds much promise. Data from the United Kingdom, South Africa, India, and Vietnam found that the 1+1 dosing schedule was equivalent or superior to the 2+1 dosing schedule with regards to pneumococcal disease incidence and pneumococcal carriage in children.

Other trials are evaluating the efficacy of a fractional dose of PCV (1/5 or 2/5 dose) compared to a full dose.

Although the 1+1 dosing schedule seems appealing, it is necessary to evaluate this schedule among children with immunocompromise and to carefully monitor pneumococcus disease and serotype epidemiology in countries that are using this schedule.

V116 Data

STRIDE-10
Since pneumococcal serotypes change, companies developing pneumococcal vaccines are constantly working to include different serotypes. This is the case for a 21-valent conjugate vaccine (V116) that is in phase III clinical trials. This vaccine includes 8 serotypes not available in any of the currently approved pneumococcal vaccines, and it is under priority review by the European Medicines Agency (EMA) and the US Food and Drug Administration). Recently, a 20-valent pneumococcal conjugate vaccine (PCV20) was approved by the EMA in February 2022 for use in adults.  

Centers for Disease Control (CDC) surveillance data for invasive pneumococcal disease (IPD) from 2018-2021 showed the serotypes responsible for approximately 83% of invasive pneumococcal disease will be covered by V116, including the 8 serotypes unique to V116 that are responsible for approximately 30% of invasive pneumococcal disease in people aged 65 years or older in the United States.

Investigators in the phase III STRIDE-10 trial evaluated the immunogenicity, tolerability, and safety of a single dose of V116 compared to a single dose of 23-valent pneumococcal vaccine, polyvalent (PPSV23), in 1484 adults aged 50 years or older who were pneumococcal vaccine–naive. For the 12 pneumococcal serotypes common to both vaccines, immune responses to V116 were noninferior at Day 30 to responses to PPSV23. For the 9 serotypes included in V116 but not PPSV23 and for 8 of those 9 serotypes, immune responses to V116 were superior compared to PPSV23, as measured by the proportions of participants with at least a 4-fold rise in immune responses. V116 had a safety profile comparable to PPSV23.

In addition, health and economic burdens of IPD and nonbacteremic pneumococcal pneumonia among adults attributable to serotypes in V116 were modeled using data from France, Sweden, Spain, and the Netherlands. Across these 4 modeling studies, the serotypes included in V116 were associated with substantially more pneumococcal cases and higher economic burden when compared to the serotypes contained in PCV20. This suggests that V116 could be beneficial at reducing pneumococcal disease in these countries. 

STRIDE-6
In adults aged 50 years or older previously vaccinated against pneumococcus, V116 elicited comparable immune responses for the serotypes shared with pneumococcal 15-valent conjugate vaccine (PCV15) or PPSV23, and it elicited higher immune responses for the serotypes covered by V116 only, regardless of the previous pneumococcal vaccine received or time since prior pneumococcal vaccination.

STRIDE-7
In adults aged 18 years or older living with HIV, V116 elicited comparable immune responses to PCV15 + PPSV23 for all 13 shared serotypes, and it elicited higher immune responses for the 8 serotypes covered by V116 only.

Conclusions
Pneumococcal disease continues to be a global public health issue, and effective vaccines are one of our best preventative measures.

What pneumococcal disease or pneumococcal vaccine data from ESCMID 2024 and ISPPD-13 are most exciting to you? Join the conversation by posting a comment.