There are no efficacy studies comparing PCV20 and PCV21.
Direct protection through vaccination of adults has been shown to reduce pneumococcal disease burden prior to the launch of PCV20.11-15§ The risk of not providing direct protection against the 9 serotypes in PCV20 and not in PCV21 is unknown.1,16‡
Disease severity
Antibiotic resistance
High prevalence
¶Based on a population-based study examining 5402 adults hospitalized for community-acquired pneumonia over a 2-year period from 2014 to 2016 in Louisville, Kentucky. One of the study limitations includes reliance on the UAD-24 platform for serotyping that can detect 24 of ~100 Streptococcus pneumoniae serotypes (1, 2, 3, 4, 5, 6A, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F), potentially underestimating S. pneumoniae cases and serotype distribution and the prepandemic time frame which may not reflect current epidemiology.17,18
- Before 2000, 7 serotypes (6A, 6B, 9V, 14, 19A, 19F, and 23F) caused most antibiotic-resistant IPD cases in the United States. Rates for all but 19A declined after the introduction of PCV719
- Between 2000 and 2010, antibiotic-resistant IPD caused by 19A rose but has since fallen sharply after the introduction of PCV13. No new serotype causing most antibiotic-resistant IPD has been found to have emerged in its place in the United States19
The impact Prevnar 20 will have on antibiotic-resistant pneumococcal serotypes is yet to be determined.
In certain adult populations in the Western US with data (Alaska, Colorado, New Mexico, Navajo Nation, and Oregon), serotype 4 has caused high percentages (ie, ≥30%) of IPD. Typically, adults who develop serotype 4 IPD are aged <65 years with specific underlying conditions or risk factors such as alcoholism, chronic lung disease, cigarette smoking, homelessness, and injection drug use.2
The most frequent causes of adult nonbacteremic pneumococcal pneumonia from 2015 to 2019 were serotypes 3, 22F, 20B, 19A, 35B, 9N, 19F, and 23A in 1 model-estimated study.20#
#Based on a model-estimated study where serotype-specific counts from 2015-2019 CDC ABCs data were used to parameterize IPD serotype distributions detectable among 101 serotypes. Serotype-specific counts from the Pneumococcal pNeumonia Epidemiology, Urine serotyping, and Mental Outcomes (PNEUMO) study supplemented with ABCs data were used to parameterize serotype distributions in adult nonbacteremic pneumococcal pneumonia. Study limitations include reliance on the SSUAD assay in the PNEUMO study to identify 30 of ~100 serotypes (1, 3, 4, 5, 6A/C, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15A, 15C, 16F, 17F, 18C, 19A, 19F, 20A, 22F, 23A, 23B, 23F, 24F, 31, 33F, and 35B), potentially underestimating S. pneumoniae cases and serotype distribution and the prepandemic time frame, which may not reflect current epidemiology. Additionally, adult nonbacteremic pneumonia serotype distribution data were collected from adults hospitalized in 2 major health systems in the southeastern United States, which may not be nationally representative nor reflective of outpatient-managed pneumonia or geographic variation. For nonbacteremic pneumococcal pneumonia caused by non-SSUAD serotypes, it was assumed their distribution resembled that in adult IPD due to non-SSUAD serotypes. Both SSUAD and non-SSUAD serotype distribution estimates were used to calculate an estimate of overall serotype-specific prevalence for nonbacteremic pneumococcal pneumonia.20
*Prevnar 20 will only help protect against the 20 Streptococcus pneumoniae serotypes in the vaccine.1
†PCV21 covers serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15B, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F, and 35B.16
‡The 9 serotypes in PCV20 and not in PCV21 are serotypes 1, 4, 5, 6B, 9V, 14, 18C, 19F, and 23F.2
§In the US, Prevnar 20 has been available for adults since 2021, and PCV21 has been available for adults since 2024.1,16
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