Many of the most vaccinated states in the U.S. are currently experiencing a surge in COVID-19 cases and hospitalizations, while the least vaccinated states are seeing their number of cases and hospitalizations trending downward.

The puzzling revelation comes at a time when the Biden administration is urging all Americans over the age of 50 to receive booster shots of the vaccine.

What are the details?

The seven most vaccinated states in the country — Vermont, Rhode Island, Maine, Connecticut, Massachusetts, New York, and New Jersey — have been hit hard over the past two weeks, according to New York Times tracking data.

In five of the seven states, both cases and hospitalizations are up by double digits. The only two outliers are Vermont and Maine. And in those states, while cases are down over the last 14 days ending on Nov. 29., hospitalizations are up 24% and 19%, respectively.

The reason may be that Vermont and Maine are still in the thick of an outbreak but experiencing a slight let-up in the virus' spread relative to where things were last week.

In each of the other states, the virus is showing no signs of dissipating. In Rhode Island and Connecticut, where 72% of the eligible population is fully vaccinated, cases are up 44% and hospitalizations are up 30% and 10% respectively.

In Massachusetts, where 71% of the eligible population is vaccinated, cases are up 32% and hospitalizations are up 44%. Finally, in New York and New Jersey, where 68% of the eligible population is vaccinated, cases are up 13% and 39% and hospitalizations are up 18% and 28%, respectively.

What else?

The inverse is true for the least vaccinated states in the country.

According to the Times data, each of the seven states with the lowest vaccination rates — West Virginia, Idaho, Wyoming, Alabama, Mississippi, North Dakota, and Louisiana — are reporting significant declines in the number of COVID-19 cases and hospitalizations over the last 14 days.

Of course, there are outliers to the apparent inverse relationship. In Washington state, where residents are 65% vaccinated, both cases and hospitalizations are down by double digits. Conversely, in both Missouri and Indiana, where just 51% of the population is vaccinated, both cases and hospitalizations are up by double digits.

It could be that the virus is plaguing certain regions of the U.S., such as the Northeast and the Midwest, to a greater degree than the Southeast without regard to the level of vaccination in those areas.

Though if that were true, it would indicate that the vaccine is relatively ineffective at stopping the spread of the virus and bringing down the number of hospitalizations, both of which have been touted as reasons to get the vaccine by public health experts.

The issue of vaccination could face another hurdle in the coming months amid the potential rise of the Omicron variant, which some fear may be resistant to current vaccines.