The persuasive power of social networks is immense, but not limitless, according to Cornell research published in March in the journal Health Economics. "Social Connections and COVID-19 Vaccination" showed that vaccine preferences, based on the COVID experience in the United States, proved quite insensitive to persuasion, even through friendship networks.
"In this paper, our goal was to ascertain if social networks can help raise the uptake of a novel vaccine in a national emergency," said co-author Nancy Chau, a professor of applied economics and policy in the Cornell SC Johnson College of Business. The other co-authors include Arnab Basu, professor of applied economics and policy in the SC Johnson College and Oleg Firsin, assistant professor of economics at the University of Maryland, Baltimore County.
Basu, Chau and Firsin looked for evidence of two types of network effects - whether social media-based friendship networks could facilitate vaccine uptake by mitigating access barriers, particularly at the beginning of the pandemic when vaccines were hard to come by; and whether these networks spread information about vaccine effectiveness based on firsthand experiences, thus influencing vaccination intentions.
While multiple studies have demonstrated the important role of social networks in a pandemic, this study did not find evidence consistent with a sustained effect linking vaccination uptake to exposure to friends who are vaccinated, suggesting that vaccination preferences are quite rigid and hard to change.
"Vaccination intentions proved insensitive to persuasion, even through friendship networks that have been shown to influence social distancing and a whole host of other health-seeking behavior," Chau said.
The National Institutes of Health has cancelled research into vaccine hesitancy and recently the Centers for Disease Control and Prevention was criticized for burying their experts' assessment that predicted the risk of catching measles was high in areas near outbreaks. With more than 650 measles cases reported in 22 states as of April 8, and slipping vaccination rates in West Texas linked to the state's largest measles outbreak in more than 30 years, what increases vaccine uptake is a major question for public health experts.
The researchers unpack the effects of social networks on both the access and information dimensions of the COVID-19 vaccination campaign.
The rollout of the COVID-19 vaccines created unprecedented public policy challenges in at least two regards. From viral sampling to approval, the COVID-19 vaccines handily beat out what was previously the fastest vaccine to go from development to deployment, the mumps vaccine in the 1960s, which took about four years. Meanwhile, the rollout of the newly approved COVID-19 vaccines took place via completely novel channels such as first-come-first-served online reservations and pop-up vaccination sites, Chau said.
The researchers wondered: How does public trust in a brand-new vaccine spread and take hold? What measures have helped individuals overcome vaccine access challenges?
"We found that friendship exposure to counties with high vaccination rates had a significant short-run impact on vaccine uptake and that these effects are more salient in counties with low pre-COVID flu vaccination rates," Basu said, adding that the COVID pandemic witnessed a surge in vaccine-hunter Facebook groups. These types of social connections can improve vaccine uptake by helping friends locate vaccine clinics or make reservations, he said, particularly at a time when vaccine supplies were scarce.
Employing weekly vaccination data at the county level in the U.S., and a wide selection of network proxies including Facebook county-to-county links, they found that exposure to vaccinated friends alone did not change vaccination behavior beyond the very short term. This suggests, Chau said, that without active life-saving public efforts to raise awareness about the importance of vaccination, a more laissez-faire approach can find vaccination uptake to be lacking even in the face of an acute outbreak.
