New data resource lists research on infection prevention from COVID-19 vaccines

About Tara Haelle

Tara Haelle (@TaraHaelle) is AHCJ's medical studies core topic leader, guiding journalists through the jargon-filled shorthand of science and research and enabling them to translate the evidence into accurate information.

Coronavirus CG Illustration

Photo: Yuri Samoilov via Flickr

Since the COVID-19 vaccines were authorized by the FDA, one of the big questions has been how well they prevent transmission of the COVID-19 even among those who have been vaccinated. The clinical trials used disease — an infection with symptoms — as the endpoint because stopping severe disease and death was the most important priority. In addition, it’s very difficult to develop a vaccine that creates sterilizing immunity, the type of immunity that prevents infection — the virus’s ability to enter cells and begin replicating.

A handful of vaccines can prevent infection, but most only prevent disease. If the COVID-19 vaccines do not prevent infection, that means a person who is vaccinated can theoretically pick up the virus, which will then replicate for a short time before the immune response takes care of it.

During that time, the vaccinated person would potentially be infectious to others, though less so than a symptomatic person since the vaccinated person would not have much virus (viral load) in their body. If, however, the vaccines can prevent infection entirely, then most vaccinated people would not be likely to pick up the virus and risk passing it on to others.

For journalists writing about these vaccination angles, a new data section at the AHCJ Medical Studies and COVID-19 Core Topics includes a list of the studies through April 20 which look at how well the vaccines prevent transmission. The list is not necessarily exhaustive, but it includes the studies I was able to track down so far.

The list includes the following studies (see the Data section for complete citations):

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