THE ASSOCIATED PRESS — The number of newly confirmed coronavirus cases in the United States has reversed course over the past two weeks, according to new data from Johns Hopkins University. Average cases have spiked from about 12,000 a day to around 19,500, according to the data.

"It is reasonable for us to start to become a little bit more cautious, to start to talk about re-implementing some measures to start to curb the spread," Dr. David Dowdy, associate professor of epidemiology at Johns Hopkins University, told The Associated Press.

Dowdy expects to see hospitalizations rise, but doesn't believe the United States will reach the incredibly high death rates it did one year ago.

"We'll probably see deaths go up, although, not to the same extent because we have more people who are vaccinated," he said.

The rise in many places across the U.S. has been blamed on too many unvaccinated people and the highly contagious delta variant.

But Dowdy thinks it's too soon to decide if a booster vaccine is needed to combat the new strain.

"There's no evidence that we have that the current vaccines that are at least being used in the U.S. are any less effective against the delta variant," he said.

On Monday, The Food and Drug Administration added a new warning to Johnson & Johnson's COVID-19 vaccine, potentially linking it to a rare neurological reaction.

Guillian-Barre syndrome is an immune system disorder that can cause muscle weakness and occasionally paralysis.

"I hope that people will look at this and realize this is the vaccine community doing its job. We are looking for side effects that are so rare that they are really close to one in a million," Dowdy said.

The number of cases reported in connection with J&J's vaccine represents a tiny fraction of the nearly 13 million Americans who have received the one-dose shot.