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Vaccines slowed, possibly degraded by obsolete delivery systems
Inadequate delivery systems are holding up and possibly dulling the effects of vaccines globally, according to a study and a literature review.
Numerous stockouts and the freezing of vaccines are among the problems researchers pointed out in the journal Vaccine.
“There are too many places in the world where vaccines are still not reaching the people who need them most,” said Steve Davis, president and CEO of the health nonprofit PATH, in a news release.
“We need to apply the same ambitious investments to vaccine delivery as we apply to vaccine development.”
PATH coordinated the publication of the study and the literature review as a supplement to Vaccine. In the study on stockouts, Patrick Lydon, MD, of the WHO Expanded Program of Immunization Plus, and colleagues found that an average of one-third of WHO member countries yearly has at least one stockout of at least vaccine for a minimum of 1 month.
Lydon and his team analyzed data from the WHO-UNICEF Joint Reporting Form and the UNICEF Vaccine Forecasting Tool in 194 WHO countries.
Stockouts plague sub-Saharan Africa the most. There, 38% of countries report stockouts on the national level, researchers found.
They also found that a national stockout yields an 89% chance that one will occur on the district level. In turn, a district-level stockout causes interruption of vaccination in 96% of cases.
The diphtheria-tetanus-pertussis (DTP) vaccine was the one most affected. During the first half of the Global Vaccine Action Plan (GVAP) — a framework to prevent millions of deaths that started in 2011 and will continue to 2020 — DTP vaccines accounted for 43% of stockouts.
The Bacillus Calmette-Guérin (BCG) vaccine for tuberculosis was the second most affected, accounting for 31% of stockouts.
Intranational, as opposed to outside, factors caused 80% of stockouts in the first half of GVAP. Of those, 39% resulted from government funding delays. Forecasting errors caused 23%, and stock management caused 18%.
In the literature review, researchers analyzed 45 studies concerning temperature variations in the cold chain. They focused on the impact of temperatures wandering outside the recommended range of 2°C to 8°C because that may make vaccines less effective.
Celine M. Hanson, PharmD, MPH, of UNICEF, and colleagues found that 33.3% of vaccine storage units in wealthier countries had seen temperatures below the recommended range, as compared with 37.1% in low income countries.
They also found that 38% of vaccine shipments in wealthier countries dipped below the recommended temperature range during transport, as opposed to 19.3% in low income countries.
The researchers stressed that unnoticed freezing, which may reduce the efficacy of freeze-sensitive vaccines, poses the threat of outbreaks. In particular, they noted a 2014 measles outbreak in Micronesia, a jump in hepatitis B during winter in Mongolia and a rise in pertussis rates in certain U.S. regions — all of which were associated with lower freezing temperatures in refrigerators used to store the vaccines.
“Expanding the use of freeze alarms and rigorous temperature monitoring is critical to ensuring that all children have access to potent, life-saving vaccines,” UNICEF principal advisor and chief of immunization Robin Nandy, MD, said in the release.
“In the long term, we must work toward the development of products that can better withstand temperature variations.” – by Joe Green
Disclosure: The researchers report no relevant financial disclosures.
Abstracts
Vaccine exposure to temperatures below recommended ranges in the cold chain may decrease vaccine potency of freeze-sensitive vaccines leading to a loss of vaccine investments and potentially places children at risk of contracting vaccine preventable illnesses …
As countries rise to the challenge of implementing the priorities of this “Decade of Vaccine” and their commitments delineated in the Global Vaccine Action Plan (GVAP), many continue to face important challenges of securing a continuous supply of essential vaccine for their national immunization programme …
Authors
Hanson CM, George AM, Sawadogo A, Schreiber B
Lydon P, Schreiber B, Gasca A, Dumolard L, Urfer D, Senouci K.