The messages members of the US Congress posted on Twitter about Covid-19 revealed rapid politicization of the pandemic, says a study.

Overall, Democrats were more likely to discuss public health and safety, as well as American workers, while Republicans emphasised a general need for national unity, discussed China and business, and framed the pandemic as a war, according to the study published in the journal Science Advances.

"It is remarkable that we could identify partisanship even when members have only 280 characters to send their messages in Twitter," said study co-author Skyler Cranmer, Professor of Political Science at the Ohio State University in the US.

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Twitter Kacper Pempel/Reuters

Twitter Reveals It All

Using Artificial Intelligence (AI) and resources from the Ohio Supercomputer Center, researchers conducted an analysis that covered all 30,887 tweets that members sent about Covid-19 from the first one on January 17 through March 31.

The algorithm they created could correctly classify the political party of the member who sent each tweet 76 percent of the time, based only on the text of the tweet and the date it was sent.

"We found that once the parties started to figure out the political implications of the issue, polarisation was evident in the tweets pretty quickly," said Jon Green, co-author of the study and doctoral student in political science at Ohio State.

Democrats sent out significantly more tweets (19,803) about COVID-19 than did Republicans (11,084), the study showed.

The gap in the number of tweets sent by Democratic versus Republican politicians widened after the first case of community spread was identified in California and grew further following the declaration of a national emergency.

"This suggests Democratic members were sending earlier and stronger signals to their constituents that they should be concerned about the crisis," Cranmer said.

What Democrats and Republicans tweeted about concerning the pandemic was different, too, results showed.

For example, the word "health" was used in 26 per cent of Democratic tweets, but only 15 per cent of Republican tweets.

Polarisation was not constant over time.

In the first full week after the first mention of Covid-19, the algorithm developed by the researchers had relatively low accuracy when trying to determine whether a Democrat or a Republican wrote a particular tweet. That indicates there was little polarisation.

However, polarisation quickly rose, peaking during the week beginning February 9. It then declined slightly in early-to-mid March before rising again in late March as the parties debated economic relief packages.

The findings suggest that Congress missed an opportunity early in the pandemic to develop a consensus that could have helped the United States respond to the crisis, Cranmer said.