Meta-analysis pinpoints global vaccination intervention strategies

Vaccines are safe and effective, and help reduce death and illness. But global vaccination rates are suboptimal and have trended downward, leaving humanity more vulnerable to vaccine-preventable diseases such as COVID-19, influenza, measles, polio, and HPV or human papillomavirus.

Identifying interventions that could increase vaccine coverage could help save lives. A new paperfrom a team led by Penn researchers offers the first comprehensive meta-analysis examining what types of vaccination intervention strategies have the greatest effect, and whether different intervention strategies work better in different countries.

"A systematic review and meta-analysis of strategies to promote vaccination uptake," published in Nature Human Behaviour, analyzes the results of 88 eligible randomized-controlled trials testing interventions with 1,628,768 participants from 17 countries. Previous meta-analyses have been more limited to specific vaccines, specific intervention strategies, or specific populations, and therefore have been unable to compare strategies or consider their relative effectiveness across regions.

"Figuring out which approaches help increase immunization, and under what circumstances, could help global public health leaders allocate resources more efficiently and ultimately improve health outcomes," says co-author Dolores Albarracín, the Amy Gutmann Penn Integrates Knowledge University Professor and director of the Communication Science divisionat the Annenberg Public Policy Center(APPC).

The researchers considered seven types of vaccine intervention strategies: increasing access to vaccination, sending vaccination reminders, providing incentives (e.g., money), supplying information, correcting misinformation, promoting active and passive motivation, and teaching behavioral skills.

The researchers found that interventions were associated with an estimated 50% higher chance of vaccination than "control" conditions with no intervention. They also found that two interventions were most promising in improving vaccination uptake. There was a moderate effect of interventions to increase access to vaccines, particularly in countries with low access to vaccines and quality of health care. The research found a small effect from incentives, and nonsignificant effects from the other interventions examined. For example, informational and misinformation-correction interventions had no detectable effects on vaccination rates.

"Public health officials often say that ensuring vaccine access is the first step to promoting immunization," Albarracín says. "Our meta-analysis provides hard evidence in support of this recommendation and indicates that this should be a special priority in under-resourced areas with limited access to health care. By contrast, even though misinformation undermines democracy and can be far-fetched, and thus highly salient, correcting it does not ensure health behaviors like vaccination."

Read more at Annenberg Public Policy Center.