Superspreading events (SSEs) are associated with a virus’ early stage “explosive” growth and sustained transmission in its later stages. These events are usually major gatherings that contain a substantial population indoors. According to the Centers for Disease Control and Prevention (CDC), COVID-19 has already killed more people than SARS and MERS combined—and these are greatly fueled by SSEs.

Here are some of the world’s SSEs that caused major COVID-19 outbreaks.

A conference in Massachusetts

Seventy-seven of Massachusetts’ confirmed cases last March was believed to have originated from the conference of a Cambridge biotech company in late February.

A wedding in Jordan

A two-hour wedding ceremony led to a massive outbreak of COVID-19 in Northern Jordan last March. Of the 350 guests, 76 caught the virus who then transmitted it to nine more people who weren’t at the wedding but were close contacts. The bride’s father was suspected to have brought the virus after arriving from Spain four days before the wedding.

A leadership conference in Boston

One hundred seventy-five executives from around the world attended a leadership conference in Boston. At least nine people contracted the virus in Massachusetts alone.

A sales conference in Singapore

In February, a man from Sussex traveled to Singapore for a sales conference where 94 out of 109 delegates came from abroad. After the conference, he was suspected to have passed the virus to 11 attendees from three countries. 

Here, the CDC has ranked the risk of COVID-19 spreading at events and gatherings:

Lowest risk: Virtual-only activities, events, and gatherings.”

More risk: Smaller outdoor and in-person gatherings in which individuals from different households remain spaced at least six feet apart, wear cloth face coverings, do not share objects, and come from the same local area (e.g., community, town, city, or county).”

Higher risk: Medium-sized in-person gatherings that are adapted to allow individuals to remain spaced at least six feet apart and with attendees coming from outside the local area.”

Highest risk: Large in-person gatherings where it is difficult for individuals to remain spaced at least six feet apart and attendees travel from outside the local area.”