The outbreak of Middle East respiratory syndrome (MERS) in South Korean hospitals is effectively over, with no new cases since 2 July. Since it began on 11 May, a total of just 186 people were infected by the coronavirus, 36 of whom have died. The episode was tragic, but its economic and social impact was disproportionate. If the world is to respond effectively to infectious-disease outbreaks, then the authorities, the media and communities must pay more attention to risk communication.

The only people at real risk of infection in South Korea were those who had shared a hospital area with someone who had MERS. Yet at the outbreak’s peak in early June, thousands of schools were needlessly closed and public events were cancelled. Tourist numbers dropped by 41% compared with the same month last year: a US$10-billion loss that is expected to knock 0.1% off the country’s gross domestic product growth this year. The only winners were those selling the ubiquitous and superfluous face masks.

One important question — and lesson to learn — is how the authorities failed both to convey the limited threat posed by MERS, and to persuade the media and public that they had the outbreak under control.

Public trust in Korean officials was already low after a perceived bungled response to the sinking of the ferry MV Sewol last year, which killed more than 300 people, many of them secondary-school pupils. When MERS struck, the authorities foolishly declined to identify the affected hospitals publicly, allowing rumours — amplified by social media — to fill the space. This faltering start was unfortunate because the government did get its act together soon after. Its transparency in reporting new cases became exemplary, as did its public-health response — including the massive task of tracing and isolating the more than 16,500 people who had been in contact with infected patients. The last contact was released from isolation this week.

Disease outbreaks are frightening, and overreaction to a virus that can kill is an understandable human response. It is one that needs to be understood and managed, not dismissed as irrational.

This puts great responsibility on the shoulders of the press and politicians, and often we see that some are not up to the job. When a handful of Ebola cases occurred on US soil last year, it sparked what President Barack Obama has described as “hysteria”. Many media reports were balanced and excellent, but too much of the reporting was excessive and sensationalist. Complicating matters further, right-wing political opportunists and pundits used the Ebola cases to take partisan shots at the Obama administration. Combined with the 24/7 news cycle, and again amplified by social media, coverage of what was a legitimate news story became a shambolic and sorry mess, utterly detached from the reality — that the United States faced no threat of an Ebola epidemic.

This had real consequences. Several politicians, including Chris Christie, the governor of New Jersey, implemented unnecessary and counterproductive measures, such as forced quarantine of US health-care workers returning from West Africa. Republican presidential hopeful Donald Trump showed a troubling grasp of the issue, and called for US borders to be sealed to those arriving from the region, including health-care workers. If this was the US response to a non-existent disease threat, what would its reaction be to a serious epidemic threat? Some outbreak-response officials think that the trend towards instantaneous news, compounded by social media, could interfere with effective public-health interventions and result in societal chaos.

Overreactions to outbreaks that pose no large threat can distract from those that do, and the priority is to eliminate the threats at source. Ebola must be stamped out in West Africa, and MERS must not be allowed to fester in the Middle East, where it is endemic in camels. Researchers need to identify and close the routes by which the MERS virus spreads to people. Social-science researchers can help to unravel complex factors affecting public reactions to outbreaks, and how authorities can build trust, so that risks can be better communicated. They might also ask how European countries managed to respond coolly to the arrival of both MERS and Ebola cases.