17 Mar The promise of reduced dose pneumococcal vaccination for children
Pneumonia is the leading infectious cause of death in children under five and, as a result, the pneumococcal conjugate vaccine, or PCV, is one of the most lifesaving vaccines. However, less than seven in every ten children are protected with PCV, well below the global target of 90%, according to official UN estimates. Further, many of countries with the largest numbers of child pneumonia deaths have among the lowest PCV coverage rates (e.g., India, Nigeria, Indonesia, Chad, Somalia, South Sudan). Of great concern, the PCV has not even been introduced in countries like Guinea, Egypt, Syria, China, Thailand, and Viet Nam where collectively 22,500 children die each year from pneumonia, according to the Global Burden of Disease.
One of the reasons for such low coverage of a lifesaving vaccine is its high cost. The PCV is the most expensive childhood vaccine and helping low-income countries afford it cost Gavi, the Vaccine Alliance $US4 billion between 2009 to 2020, more than any other vaccine. As countries grow and graduate from Gavi support there are concerns about their ability to sustain the high costs of their PCV programs, while countries who are ineligible for Gavi support continue to cite high cost as a barrier to PCV introduction.
A recent World Health Organization (WHO) Global Vaccine Market Report highlights the PCV as an example of a vaccine with “poor market health,” citing as evidence the market dominance (80%) of just two vaccines (Pfizer and GSK), the wide variation (18-fold) in PCV prices across countries, and the sharp increase (%) in price in recent years. Concerns about high PCV prices have even motivated the World Society for Pediatric Infectious Diseases (WSPID) to launch a Call to Action for Fair Vaccine Prices, with more than 500 organizations signing on.
What is PCV 1+1?
In the context of high and rising PCV prices, new evidence on the effectiveness of reducing the dosing schedule from three or four doses to two holds much promise, because it would reduce the cost of PCV programs by one third. A new group of studies has measured what happens to two different groups of children vaccinated with the same PCVs at different times. The first group of children typically receive a PCV three times a year (at 2, 4 and 6 months, or 2, 4, and 12 months) in what is called a 3+0 or 2+1 dosing schedule. The other group of children get a PCV just twice (at 2 and 12 months, or 6 weeks and 9 months) in what is called a 1+1 schedule. The first dose/s are called “primary” doses, while the final dose is called the “booster” dose.
After vaccination, both groups of children are tested to see if there are differences in “immunogenicity” and “nasopharyngeal carriage.” Did two PCV doses provoke a weaker immune response in the children with less impact on pneumococcal bacteria in the nasopharynx, the upper part of the throat behind the nose? If two PCV doses are not as effective as three at stimulating the immune system to produce antibodies and at reducing the presence of pneumococcal types in the children’s throats, three doses are clearly needed. The vaccines used in these studies typically include Pfizer’s PCV13 (Prevenar) and GSK’s PCV10 (Synflorix), with one study using Serum Institute of India’s PCV10 (PNEUMOSIL).
What are the PCV 1+1 studies finding?
The studies that have either already reported or are underway include three in high-income countries (UK and Canada), five in middle-income countries (South Africa, India, Vietnam, Thailand), and one in a low-income country (The Gambia). In 2018, the UK study found that the 1+1 schedule was equivalent or superior to the 2 + 1 schedule and concluded that, “introducing a 1 + 1 schedule in countries with a mature PCV programme and established herd immunity is likely to maintain population control of vaccine-type pneumococcal disease.” As a result, the UK introduced a 1+1 schedule in 2020 and a recent assessment found that pneumococcal disease incidence was lower in 2022 than in 2019. The Canadian study is comparing 2+1 and 1+1 and has not yet reported results.
The studies in South Africa, India, and Viet Nam have all reported comparable immunogenicity in both the 2+1 and 1+1 groups. The South African study concluded, “the non-inferiority in post-booster immune responses following a single-dose compared with a two-doses of PCV13 or PCV10 indicates the potential for reducing PCV dosing schedules from a 2 + 1 to 1 + 1 series in low-income and middle-income settings with well established PCV immunisation programmes.” A subsequent analysis found that the serotype-specific colonization data also support transitioning to a 1 + 1 schedule in South Africa and recommended ongoing monitoring of colonization immediately before and after transitioning.
The India study concluded that immune protection from 1 + 1 schedules is comparable to WHO-recommended 3-dose schedules, and the first Viet Nam study in Ho Chi Minh City found that a 1 + 1 PCV schedule, “greatly reduces vaccine-type carriage and is likely to generate substantial herd protection and provide some degree of individual protection during the first year of life.” The second Nha Trang study is currently testing the 1+1 schedule compared to the standard 2+1 and 3+0 schedules, and exploring the impact of a single dose schedule. The Thai trial is testing two doses of PNEUMOSIL, the only trial to use the more affordable PCV10.
Importantly, The Gambia trial, the only 1+1 trial in a low-income, African setting, has found no differences in pneumonia incidence among the children in the PCV 1+1 group relative to the 3+0 group (publication in process). Another study from Burkina Faso, tested multiple PCV schedules across different age-groups (<1, 1-2 years, 2-4 years) and found that one or two doses produced good immune responses in 1 to 4 year olds.
What about one-dose and fractional PCV doses in humanitarian settings?
In addition to these routine vaccination trials, there are others looking at the impact of just one dose or a fraction of a dose of PCV for children living in fragile settings in Niger, Kenya, and Somaliland. In the Epicentre/MSF study in Niger, some children aged one to nine years got one full PCV dose while others got a fractional dose (20% of a single dose). The results showed that fractional-dose campaigns met non-inferiority criteria and the authors recommended they should be considered in low-coverage settings, including humanitarian emergencies, to accelerate population protection. The fractional dose trial in Kenya found a 3-dose schedule using 40% of the standard dose of PCV13 was non-inferior to the standard dose.
In the Somaliland study, children under five living in the Digaale camp for Internally Displaced Persons (IDP) received a single PCV dose, preventing 27% of severe pneumococcal disease with the authors concluding that, “single-dose PCV mass-vaccination campaigns offer crisis-affected populations an effective, pragmatic immunization strategy.”
Unlike the routine vaccination studies, two of the humanitarian studies are using the Serum Institute of India’s PCV10. The results of these studies will be extremely important to the implementation of Gavi’s 6.0 Strategy with its focus on how to deliver vaccines when government service provision is compromised or non-existent.
What else can be done to reduce the costs of PCV programs?
Reducing PCV dosing schedules is not the only way to improve the financial sustainability of PCV programs. Countries can elect to switch to the Serum Institute of India’s PCV10; with a Gavi price of $US2.00 per dose it can cut costs by one third, but so far too few have. The Serum Institute has recently offered Latin American countries who are members of the Pan-American Health Organization (PAHO) the Gavi price. Gavi could go further and extend its PCV price to currently ineligible countries, or subnational populations, with large numbers of childhood pneumonia deaths.
Increased efforts to improve market competition by supporting companies to develop more cost-effective PCVs is also needed. The Gates Foundation is currently supporting a new low-cost 25-valent PCV (IVT PCV-25) from US company Inventprise is currently in clinical trials, and Australian company GPN Vaccines is also working on a new pneumococcal vaccine.
Which countries should switch to two PCV doses?
WHO commissioned a review of the trial evidence and published a Position Paper in September 2025 recommending that strong contenders for a 1+1 switch would include countries with, a) well-established pneumococcal immunity among children <5 years (i.e., ≥80% PCV coverage for five preceding years, or ≥80% PCV coverage following PCV campaign among children <5 years, or low levels of vaccine-type carriage or disease), and b) evidence of capacity to administer vaccination between the ages of 9 and 18 months (i.e., average coverage of ≥80% in preceding five years for the PCV booster, measles-containing vaccine, yellow fever vaccine, or meningococcal conjugate vaccine).
Currently, 21 Gavi-eligible countries meet these requirements including Malawi, Sierra Leone, Kenya, Lesotho, Rwanda, Sao Tome, Tanzania, Zimbabwe, Mauritania, Burundi, Eritrea, Ghana, Burkina Faso Senegal, Uganda, Zambia, Cambodia, Pakistan, Bangladesh, Kyrgyzstan, and Nepal.
But so far, the UK is the only country to switch to two PCV doses. While an academic consensus is emerging that the majority of the infant population will have good protection from a two-dose PCV schedule, concerns remain that immuno-compromised children (e.g., malnourished, HIV positive, etc.) could still benefit from additional PCV doses. Experts also caution that low compliance with the booster dose could undermine impact, and that governments will need robust disease surveillance to monitor cases of serious disease between primary and booster doses.
With new vaccines for malaria, HPV, and Respiratory Syncytial Virus (RSV) on their doorsteps, the vaccine pipeline growing every year, and global health aid declining, the fiscal space for new vaccines is shrinking. And with the 2030 Sustainable Development Goal deadline fast approaching, governments need to find ways to simultaneously reduce the cost of their childhood vaccine programs and accelerate child mortality reductions. Reducing the PCV schedule could be one of them, especially if the cost savings from a 1+1 schedule were used to increase vaccine coverage of PCV or other lifesaving vaccines, like the maternal vaccine that prevents RSV, the leading cause of hospitalization in infants.
Download a summary of current studies on one simple table with clicks to research here
World Pneumonia Day, 12 November 2025