US closely watching Covid surge for clues

Covid-19 cases are spiking in South Africa, and public health experts in the United States are following the data closely, waiting to see wh...

Covid-19 cases are spiking in South Africa, and public health experts in the United States are following the data closely, waiting to see what it might reveal about how immunity from previous infections behaves over time.

https://ift.tt/rIUMqWg