Pandemic Perspective #36   December 12, 2020

Superspreaders: today’s Typhoid Marys

            Mary Mallon was an unfortunate carrier of Salmonella typhi, the bacterium that causes typhoid fever. In the early 20th century she worked as a cook for several wealthy families in the New York City area where over two decades she infected 53 people, three of whom died of typhoid fever.

            More than a century later she would be outperformed – by a country mile – by COVID-19 superspreaders, persons who shed enormous numbers of virus particles. One of these was identified in the state of Washington where a singer infected 53 members of her choir, accomplishing in about two hours what it took Typhoid Mary to wreak over several years. A few other superspreaders have been identified in other parts of the world. They make for dramatic headlines but the illnesses that they ignite are few relative to the enormous number of cases, now exceeding 71 million throughout the world with more than 1 ½ million deaths.

            Superspreader events are more common and they have been observed in prior coronavirus pandemics, SARS and MERS. COVID-19 cases have erupted where large numbers of people congregate, especially when they mingle closely and ignore reasonable guidelines. These range from a church wedding to a swingers’ convention to a conference of biotechnology workers. The fallout from that gathering of scientists may have led at least indirectly, according to one study, to as many as 20,000 cases! Several events were initiated by persons who were in attendance in spite of having symptoms of COVID-19.

            As we enter the second year of the COVID-19 pandemic we all feel coronavirus fatigue and frustration but we need to face the reality that the current surge has not yet peaked. Some of the draconian restrictions imposed by politicians are ill-conceived and are not rooted in science – we should encourage, not restrict, outdoor activities and get our kids back in school. On the other hand we need to continue the practices that are effective, including avoiding crowded venues, maintaining social distancing outside the household and being tested if you are aware of having been exposed to a positive contact. Wearing an effective mask and wearing it properly does help, but only to a limited degree, and should not make us complacent about the other guidelines.

            Today’s dismal numbers will improve in the coming year as the most susceptible and the most at-risk persons receive a vaccine.