A study in Vaccine presents a comparison of the impact and cost-effectiveness (CE) of vaccination against pneumococcal disease in England. Pneumococcal disease, which presents as invasive pneumococcal disease (IPD) or community-acquired pneumonia (CAP) is an “important cause of illness and hospitalisation” in the elderly. In 2003 a 23-valent pneumococcal polysaccharide vaccine (PPV23) became available to 65-year-olds in England. The study investigates how it compares with new 15- and 20-valent pneumococcal conjugate vaccines (PCV15 and PCV20) for adults aged 65 or 75.
Pneumococcal disease
The authors state that Streptococcus pneumoniae is an “important cause of serious infection”, with highest rates observed in infants, the elderly, and patients with chronic respiratory disease or who are immunocompromised. The burden of pneumococcal disease in England is “significant”.
“Over the period of 2010-2019, there were 400-600 annual cases of vaccine-type IPD and 1,200-2,200 cases of non-vaccine-type annual IPD in people over 65 years old.”
Before COVID-19, between 0.5% to 1% of adults in the UK experienced community-acquired pneumonia (CAP) each year. However, vaccination against pneumococcal disease can “reduce the burden” of both IPD and CAP.
Pneumococcal vaccines
There currently two types of pneumococcal vaccines available: the polysaccharide vaccine and the conjugate vaccines. The 23-valent polysaccharide vaccine (PPV23) covers 23 out of more than 100 known pneumococcal serotypes; it was recommended for risk groups in England in 1992 and was expanded to include all adults over 65 in 2003. While it offers protection against vaccine-type IPD, it has “limited effectiveness” against CAP.
The 7-valent pneumococcal conjugate vaccine (PCV7) was licensed in the UK in 2006 for use in children before its replacement by PCV13 in 2010. Conjugate vaccines have demonstrated protection against vaccine-type IPD and vaccine-type CAP. However, since 2013/14, an increase in overall incidence of IPD has been observed, which the authors attribute to increases in non-PCV13 vaccine serotypes.
Two new, higher-valent conjugate vaccines were recently approved by the Medicines and Healthcare products Regulatory Agency (MHRA): PCV15 and PCV20. They cover the 13 serotypes included in PCV13 with additional serotypes.
“In light of the observed epidemiology and availability of higher-valency vaccines there is a need to re-evaluate the current pneumococcal immunisation programme in England.”
The authors evaluated the impact and cost-effectiveness of differently elderly immunisation strategies against pneumococcal disease in England. They developed a static Markov model comprising two parts: an epidemiological model to estimate disease burden, and an economic model to calculate the costs incurred from disease burden. 5 immunisation strategies were modelled: 3 individual vaccine strategies with PPV23, PCV15, or PCV20 and targeting a naïve population, and 2 combined strategies where PCV15 or PCV20 were administered to a population already vaccinated with PPV23. In each strategy the vaccination ages considered were 65 and 75.
What does the study find?
The results indicated that, of the individual strategies, across both IPD and CAP cases averted, vaccination with PCV20 was the “most effective strategy when vaccinating at either 65 or 75 years of age”. Both PCV20 and PPV23 “could be cost-effective”, but this depends on the effectiveness/waning scenario.
“Our findings highlighted that both PCV20 and PPV23 can be cost-effective vaccines that would effectively reduce the pneumococcal burden in the elderly in England.”
Therefore, the authors encourage consideration of both vaccines within the national elderly pneumococcal immunisation programme in England. However, there are “other considerations”, such as “equity issues” and delayed immunisation.
“Policy decision makers need to take into consideration the wider implications of amending or changing the national pneumococcal immunisation strategy for elderly in England.”
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