More than 70% of Massachusetts residents over 16, and more than 55% of adults nationwide, have now been at least partially vaccinated against coronavirus, showing significant progress in the months-long campaign to get large swaths of the population inoculated. Some states are getting creative, offering cash or even free beer to entice their residents to get the vaccine.

But with demand for shots beginning to slow, many medical experts are warning that the United States will not reach the herd immunity that public health officials have emphasized for so long. Dr. Cassandra Pierre, acting hospital epidemiologist and medical director of public health programs at Boston Medical Center, and Dr. Michael Mina, an assistant professor of epidemiology at Harvard’s T.H. Chan School of Public Health and associate medical director in the department of pathology at Brigham & Women’s Hospital, joined Jim Braude on Greater Boston to discuss.

WATCH: Epidemiologists on herd immunity and getting populations vaccinated