We all know that more thoroughly and frequently washing our hands is among the most effective measures we can take to curb the spread of COVID-19.

Hand-washing also happens to be relatively costless and generally beneficial. Yet polling from Reuters/Ipsos in the first week of March showed that in the US, more than half of Republicans had not altered their hygienic routines in response to the COVID-19 pandemic. By contrast, most Democrats had altered their habits and were twice as likely as Republicans to regard the virus as a threat.

In the US, more than half of Republicans had not altered their hygienic routines in response to the COVID-19 pandemic.

I hope that reactions among Republicans have since shifted, though follow-up polling by Ipsos and USA Today and by NBC News and the Wall Street Journal, both in the second week of March, show similar trends. There is some comfort in the fact that President Trump has recently pivoted from suggesting the pandemic is “the new hoax” driven by a WHO “false number” to referring to it as a “foreign virus” that has occasioned a national emergency. In any case, and assuming that the polling data gives an accurate snapshot of initial responses to the pandemic in the United States, the partisan divide is not surprising. Here’s why.