Vaccinate the 'super-spreaders' first

A committee of the National Academies has proposed a framework for allocating a #covid19 vaccine. Unfortunately, as Matt Kahn, David Conti, and I point out in The Conversation, some of their priorities are wrong.

The #NASEM committee is right to prioritize first responders, health care workers, and older adults in congregate living situations. But then they take a wrong turn. ((Full disclosure: I am a member of the National Academy of Medicine.)

The National Academies prioritize people based on their personal risk of morbidity and mortality. We argue the priority should be transmission risk.

We have seen firsthand at USC the real risks of rapid, asymptomatic spread of COVID-19 among younger adults. And it isn't just our school. Asymptomatic spread is shutting down schools and universities nationwide and threatening surrounding communities. How do we balance personal risk and transmission risk?

Influenza does provide a useful model. The priority to protect the most frail has been public policy since at least the 1957-1958 influenza pandemic. However, the models from past flu pandemics suggest other strategies may work better. There is often a better way to protect older people by controlling spread among the young, which means vaccinating school-age children early. More generally, vaccinating the asymptomatic spreaders can avert multiple infections with others.

This is particularly true with COVID-19. A recent study found that as few as 10% of those infected lead to 80% of the infection cases. What has made it more difficult is that up to 40% of those who carry the virus, often known as superspreaders, show no symptoms at all.

Very few of the COVID-19 superspreaders are elderly. And these models need to account for behavior. It is the younger people who will resume their social lives more quickly when a vaccine emerges--indeed they are doing it already.

Some would argue they have less risk, which is true. But this also means they are more likely to infect others. Cases have been spiking in the 15- to 25-year-old age group, another likely sign that they are propelling the spread of the virus. A recent outbreak on the University of Southern California’s fraternity row infected at least 40 people.

More broadly, younger residents in the virus hot spot of Los Angeles County make up the majority of positive new cases. In California, young people between 18 to 34 years of age account for more than one-third of cases.

With or without a vaccine, the best strategy for older Americans, especially those with underlying medical conditions, is avoiding contact with potential carriers. Optimally, older people will drive down deaths by staying home in large numbers, and younger people will drive down infections by getting vaccinated in even larger numbers. It all works if the vaccine is effective and enough people take it.