As the COVID-19 vaccination rate slows down in the U.S. — according to the Centers for Disease Control and Prevention, only about 54 percent of the eligible population was fully vaccinated as of Monday morning — red states are falling behind. The lowest vaccination rates are in deep-red states like Mississippi and Alabama, while deep-blue states like Vermont and Massachusetts have had far more success in vaccinating their residents.

This widening gulf between red and blue states has reignited fears that politics is seriously undermining the nation’s vaccination efforts. And for good reason: There is a stark and growing divide in the vaccination rates in Republican- and Democratic-leaning parts of the country. But the singular focus on politics ignores the critical role that social pressure plays in deciding whether to get the COVID-19 vaccine.

For starters, Republicans are simply less likely to have friends who have been vaccinated. In a May survey conducted by the American Enterprise Institute’s Survey Center on American Life, where I serve as director, less than half of Republicans (46 percent) said that most or all of their friends had received at least a single dose of the vaccine. For Democrats, meanwhile, vaccination is the norm among their peers. Two-thirds said that most or all of their friends had been at least partially vaccinated.

Moreover, Republicans were far less likely than Democrats in this survey to have received any encouragement from friends or family members to get vaccinated (28 percent versus 55 percent, respectively). In fact, one in three Republicans reported that friends or family had advised them not to get the vaccine or that they had received mixed messages about the importance of getting one.

This finding is noteworthy because while partisanship is a factor in influencing our behaviors, social science research consistently shows that our friends exert a profound — and often invisible — influence on us. For instance, if you have friends who smoke or are obese, your chances of smoking or being obese increase significantly.

So it may be for getting the COVID-19 vaccine.

Read the full article about peer pressure by Daniel Cox at FiveThirtyEight.