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Here’s why it matters. The risk for pneumococcal disease rises with age, with the highest risk among those aged 65 or older and younger adults with chronic medical or immunocompromised conditions. These groups carry more than 90% of the burden of invasive pneumococcal disease in adults.
Invasive pneumococcal disease (IPD) includes meningitis, bacteremia, and bacteremic pneumonia. In 2019, an estimated 30,000 cases of IPD resulted in 3000 deaths. Nonbacteremic pneumonia is classified as noninvasive disease. In 2017, more than 100,000 adults aged 19 or older were hospitalized with pneumococcal pneumonia.
The previous pneumococcal vaccine recommendation was complicated and confusing. The new recommendations are much more straightforward, with only two options to choose from:
- A two-vaccine sequence of PCV15 (brand name Vaxneuvance), followed by PPSV23, a polysaccharide vaccine (brand name Pneumovax 23), or
- A single dose of the new PCV20 vaccine (brand name Prevnar 20).
If you choose the dual vaccine option, give PCV15 first. But no matter the order, the recommended interval between PCV15 and PPSV23 is at least 1 year. However, for those with immunocompromising conditions, cochlear implants, or cerebrospinal fluid leaks, a minimum of 8 weeks can be considered.
PPSV23 is a pneumococcal polysaccharide vaccine that is made from capsular polysaccharide antigens. It does not produce memory B cells, and it is T-cell independent. Capsular polysaccharides found in pneumococcal conjugate vaccines are conjugated to a nontoxic diphtheria protein carrier called CRM197, thereby inducing higher levels of immunologic memory.
However, there is some concern that starting with the polysaccharide vaccine can blunt the immune response to the conjugate vaccine. That’s why PCV15 should ideally be given first.
PCV15 includes the same strains as PCV13, plus protection from two additional serotypes. PCV20 expands protection to five more. PPSV23 protects from serotypes covered by PCV20, with one exception: type 6A. It also covers four additional serotypes that are not included in the PCV20 repertoire.
Here is the background on why there are two pneumococcal vaccine options. ACIP looks at available data. No head-to-head safety and efficacy studies have compared PCV20 with PCV15. A study comparing PCV20 with PCV13 showed that PCV20 triggered a lower immune response for 12-13 of 13 shared serotypes. However, the clinical relevance of this lower immunogenicity for PCV20 vs PCV13 is unknown. PCV20 is likely to provide improved protection against the five serotypes included in PPSV23, but not in PCV15. If you give PCV20 alone, you lose protection against the serotypes unique to PPSV23. Hence the two options.
Both options are included in the new ACIP adult schedule (Table 1 shows vaccines by age and Table 2 shows vaccine recommendations based on medical conditions and other indications). The new recommendation is simpler, but it may not stay that way. Some workgroup members favored a universal, age-based recommendation, starting at age 50 years rather than 65. This would provide more opportunities to vaccinate adults but could lead to waning immunity later in life when risk for disease is higher.
Administering PCV15 in series with the PPSV23 combo presents more logistical challenges, thus more controversy. Some workgroup members favor giving a dose of a higher-valent PCV to those who already had received PCV13 with or without PCV23. This did not happen. ACIP did not make this concession or recommendation. ACIP makes evidence-based decisions, and the incremental benefit of giving a higher valent PCV to those who had already received a dose of lower-valent PCV13 has not been studied.
Créditos: Comité científico Covid