“What’s important to understand is that all of these things add up,” said Marc Lipsitch, a professor of epidemiology at Harvard’s T. H. Chan School of Public Health. “A modest amount of help from herd immunity combined with partially effective control measures, combined with the fact that it’s summer.”

But he also cautioned that the slow, downward slope of new cases in South Florida isn’t a reason to abandon any safeguards at all. The safeguards are one of the main reasons for the declines.

“Each of those is making a contribution to the trajectory in Miami and elsewhere. … Herd immunity alone would not be enough to get us out of this pandemic at the current levels,” he said.

At Jackson Health System, Miami-Dade’s public hospital network, CEO Carlos Migoya told the Miami Herald this week that the downward trend in new cases and hospitalizations could be reflective of partial herd immunity but like Lipsitch, he emphasized that personal protective measures are a major piece of the equation.