Above: Photo by Charlie Forgham-Bailey, Save the Children. Democratic Republic of Congo (DRC). Vaccinations are given at various points during the child's development, and helps prevent numerous ailments, including pneumonia.
by Cynthia Whitney, IHRC, Inc. and Emory Global Health Institute
To those of you who do not spend your day thinking about infant vaccines, it may come as a surprise that the timing of vaccine doses can have a big effect on how well they work. Sometimes giving doses too close together, at the same time as other types of vaccines, or too early in life can reduce the immune system’s response to a vaccine. A poor immune response means a vaccine may not prevent disease.
Vaccines are a key weapon in the fight against pneumonia. Over the last decade, most infant immunization programs around the world have starting using pneumococcal conjugate vaccines (PCVs), and the data from countries using PCVs have shown a promising drop in the burden of pneumonia. More work is needed to make sure PCVs are available to all children, however. Of the 15 countries with the largest numbers of pneumonia deaths in children, 4 still do not include PCV in their immunization programs, and, of the 11 that do, only 3 have coverage levels for 3 doses above the 90% mark.
Over the last few years, the question of whether the timing of PCV doses can be adjusted to improve pneumonia control has been a hot topic in the scientific community. Many experts believe that spreading out the three doses that are typically given in the first few months of life to give the third dose at 9 months or later will result in more long-lasting protection for children receiving the vaccine. This type of schedule, known as “2+1,” may also better prevent spread of pneumococcal bacteria, protecting those who are too young or too old to receive the vaccine themselves. The 2+1 schedule is used in many European countries and in South Africa; in 2018, Australia changed to a 2+1 schedule in response to cases of severe pneumococcal disease that were occurring in older children.
In most African countries, however, long-standing practice has been to give immunizations including PCV doses during routine visits at about 6, 10 and 14 weeks of age, a schedule designed to provide protection from vaccine-preventable diseases as early in life as possible. Over the past few years, deadly pneumococcal meningitis epidemics have occurred in Ghana, in spite of a successful infant immunization program that has achieved high coverage with 3 early doses. These outbreaks, along with other data suggesting that pneumococcal disease and transmission are not completely controlled in countries using 3 early PCV doses, is encouraging policy makers to reconsider their national PCV immunization schedules.
A new statement from the World Health Organization’s (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization now strongly supports use of the 2+1 schedule for PCV, in an effort to improve control of pneumococcal pneumonia and meningitis. The SAGE statement, released in February 2019, encourages use of the 2+1 schedule even for countries that have for years been providing three early doses. Changing the timing of vaccine delivery will require planning, training, new materials such as immunization cards, and follow-up to ensure that vaccine delivery is good – substantial commitments of time and resources from immunization programs. Going forward, however, this investment in changing to an innovative vaccine schedule will result in better control of pneumonia and other types of severe pneumococcal disease, and lives saved.
 International Vaccine Access Center (IVAC), Johns Hopkins Bloomberg School of Public Health. (2018). Pneumonia and Diarrhea Progress Report 2018. https://www.jhsph.edu/ivac/resources/
2 Bozio CH, Abdul-Karim A, Abenyeri J, et al. (2018) Continued occurrence of serotype 1 pneumococcal meningitis in two regions located in the meningitis belt in Ghana five years after introduction of 13-valent pneumococcal conjugate vaccine. PLoS ONE 13(9): e0203205. https://doi.org/10.1371/journal.pone.0203205
3World Health Organization. Pneumococcal conjugate vaccine in infants and children under 5 years of age: WHO position paper – February 2019. Weekly Epidemiological Record 2019; 94 (8):85-104. https://apps.who.int/iris/bitstream/handle/10665/310968/WER9408.pdf?ua=1
About the author: Cynthia G. Whitney, MD, MPH is a physician and epidemiologist who retired in 2018 after 25 years with the U.S. Centers for Disease Control and Prevention, where she served as Chief of the bacterial Respiratory Diseases Branch, among other roles. She is now a consultant for IHRC, Inc. and Emory Global Health Institute.