(C) Our World in Data This story was originally published by Our World in Data and is unaltered. . . . . . . . . . . When less is more: how many doses of PCV are enough? [1] ["Katherine L O'Brien", 'Klobrien Jhu.Edu', 'Johns Hopkins Bloomberg School Of Public Health', 'Baltimore', 'Md', 'Goldblatt D', 'Southern J', 'Andrews Nj'] Date: 2022-11 1 Advisory Committee on Immunization Practices Preventing pneumococcal disease among infants and young children. Recommendations of the Advisory Committee on Immunization Practices (ACIP). 2 WHO Pneumococcal conjugate vaccine for childhood immunization. WHO position paper. 3 WHO Pneumococcal vaccines. WHO position paper 2012. , 4 Wahl B, O'Brien KL, Greenbaum A, et al. Global burden of Streptococcus pneumoniae in children younger than 5 years in the era of pneumococcal conjugate vaccines (PCV): 2000–2015. 10th International Symposium on Pneumococci and Pneumococcal Disease. Glasgow, Scotland. June 27–30, 2016. 67. 5 Centers for Disease Control and Prevention Pediatric/VFC vaccine price list. Pneumococcal conjugate vaccine (PCV) is an incredibly important, lifesaving vaccine, first licensed in 2000,and recommended for infant routine use in the UK in 2006.Since 2007 WHO has recommended it for inclusion in the routine infant immunisation schedule of all countries.Up to now, it has been rolled out in the national immunisation programmes of 141 countries ( figure ), has saved hundreds of thousands of lives,and is projected to save millions in the decades to come as country introductions continue and coverage increases. Figure Countries that have introduced pneumococcal conjugate vaccine into their routine immunisation programme Show full caption PCV=pneumococcal conjugate vaccine. NIP=national immunisation programme. Figure reproduced with permission from VIEW-Hub.org on Nov 10, 2017. 6 UNICEF Product menu for vaccines supplied by UNICEF for Gavi, the Vaccine Alliance. 7 Pan American Health Organization Expanded program of immunization vaccine prices for year 2017. However, PCV cost threatens this progress. In 2017 prices range from a low of US$3·05 per dose for the poorest countries of the world, supported by Gavi, the Vaccine Alliance,to $169 per dose in the US private sector.Many middle-income countries, too wealthy for Gavi support, but unable to afford market driven prices, are left out. Furthermore, Gavi countries are starting to transition out of full support as their economies strengthen and may face harsh economic realities of PCV affordability into the future. Strategies to reduce PCV programme costs, without compromising disease protection need to be pursued. 8 Goldblatt D Southern J Andrews NJ et al. Pneumococcal conjugate vaccine 13 delivered as one primary and one booster dose (1+1) compared with two primary doses and a booster (2+1) in UK infants: a multicentre, parallel group randomised controlled trial. In The Lancet Infectious Disease, David Goldblatt and colleagues report much anticipated immunogenicity results of a novel two-dose PCV infant vaccination schedule compared with a standard infant three-dose schedule.As expected, immunogenicity of a single priming dose (1p) was inferior to two doses (2p). However, serotype-specific immunity following the booster dose of both schedules (1p + 1 and 2p + 1) was equivalent for most serotypes, showing that immunogenicity of the PCV booster dose is relatively independent of the number of priming doses received. This is why we care so much about the results of this immunogenicity trial, designed to answer a rather simple scientific question, but a pivotal policy question. We could be at the beginning of a clever “less is more” approach to pneumococcal disease control. The rationale for a reduced-dose PCV schedule centres on the observation that when three-dose or four-dose PCV infant schedules achieve prolonged, high coverage, vaccine serotype pneumococcal disease is virtually eliminated, as is vaccine serotype nasopharyngeal carriage in the community. The subsequent a priori risk for vaccine serotype pneumococcal disease in infants becomes extremely low because the organisms are no longer in widespread circulation. As long as community-wide immunity is sustained, there is limited rationale for inducing high immunity in the youngest infants, which requires using multiple PCV doses. Instead, immunising new birth cohorts with a single dose of PCV in the second year of life should succeed in maintaining high population immunity; adding a single PCV priming dose in early infancy, as was done in this study, not only enhances toddler immunity but is intended to also confer early, direct, albeit imperfect, immunity to these youngest infants in the event that they have exposure to vaccine serotype pneumococci before receiving their booster dose. This approach is a intended as a belt-and-braces strategy. The findings of this UK-based immunogenicity study have the potential to initiate a sequence of events that could reduce the number of PCV doses needed by programmes, provide enhanced global PCV access, and save billions of dollars in the process. But, much still needs to be assessed before that could happen. 9 WHO/UNICEF WHO/UNICEF estimates of national immunization coverage. Progress and challenges with achieving universal immunization coverage: 2016 estimates of immunization coverage (data as of July, 2017). The effect of a 1p + 1 PCV maintenance programme would require careful monitoring through sustained, high quality pneumococcal disease surveillance as exists in the UK. However, questions about generalisability remain, especially for high disease burden settings. It is crucial to assess whether a 1p + 1 PCV schedule can prevent the acquisition of vaccine serotype pneumococcal colonisation among those immunised; this can only be established through studies in which vaccine serotype pneumococci are still in circulation. High, sustained coverage of the PCV booster dose is essential; worldwide, coverage with second dose measles vaccine, given in the second year of life, is only 60%.The epidemiological settings in which a PCV reduced dose approach might work are those in which adults contribute little to sustaining pneumococcal transmission; however, for high disease burden settings, this is often not the case. Finally, the effect of a reduced dose PCV schedule on vaccine serotype nasopharyngeal colonisation must be resilient to fluctuations in coverage or delays in dosing, which occur often in settings with fragile supply chains and frequent vaccine stock-outs. Studies to assess some of these issues are underway. 10 Gong W, Knoll MD, Hammitt L, et al. Reduced pneumococcal conjugate vaccine (PCV) dosing schedules for maintenance of impact: a review of the technical evidence and a policy analysis. 10th International Symposium on Pneumococci and Pneumococcal Disease, Glasgow, Scotland. June 27-30, 2016. 088. If future evidence concludes that three PCV doses are not likely necessary for the maintenance of the public health and individual protection gains already achieved, vaccine policy makers should be fully willing to consider sustaining disease protection with the fewest possible doses. In spite of all the constraints on which countries might meet epidemiological conditions that would allow a switch to a 1p + 1 schedule, it is estimated that savings of roughly $1·5 billion could be accrued over a 10-year time period in Gavi eligible countries alone.That would be a compelling “less is more” proposition. Copyright © 2018 Mike_Kiev KLOB reports grants from Pfizer, GSK, Gavi, and BMGF, and other from Merck, outside the submitted work; and service on WHO SAGE. [END] --- [1] Url: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(17)30684-9/fulltext?elsca1=etoc Published and (C) by Our World in Data Content appears here under this condition or license: Creative Commons BY. via Magical.Fish Gopher News Feeds: gopher://magical.fish/1/feeds/news/ourworldindata/