How Unvaccinated States Are Feeling Brunt of Delta Variant Uptick – The New York Times

Coronavirus cases and hospitalizations in the United States remain low but are slowly rising again, driven by outbreaks in patches of the country’s center, south and west, and by tiny increases almost everywhere else.

The highly contagious Delta variant, which now makes up a majority of new U.S. cases, has spread rapidly, fueling the national uptick. But because vaccines are effective against the variant — especially against serious disease — new cases and hospitalizations are primarily climbing in places with low vaccination rates.

Public health experts expect this trend to continue, putting the country’s vaccinated and unvaccinated on very different paths in the next phase of the pandemic. While nearly half of the entire population is fully vaccinated, the level of protection varies widely across and within states.

Covid-19 hospitalization rates, an indicator of serious illness, have increased more drastically over the past two weeks in many states where vaccination levels are comparatively low and where the Delta variant is driving a surge in cases, including Arkansas, Mississippi and Missouri.

“Please know if you are not vaccinated, you remain susceptible, especially from the transmissible Delta variant, and are particularly at risk for severe illness and death,” Dr. Rochelle P. Walensky, director of the Centers for Disease Control and Prevention, said at a recent news conference.

In Mississippi, where just 34 percent of the population is fully vaccinated, cases, outbreaks and hospitalizations are all on the rise. Officials there have recommended that older adults and those with chronic medical conditions avoid large indoor gatherings through July 26.

“We did predict a few weeks ago that the Delta variant would be the predominant strain circulating in the state of Mississippi,” Dr. Thomas Dobbs, the state health officer, said at a news conference last week. “Unfortunately, those predictions are becoming reality, and we’re starting to pay the price for it,” he said, pointing to outbreaks among youth from summer gatherings and among older populations in nursing homes.

He added: “Our collective undervaccination in the state has put us all at risk, especially the most vulnerable.”

Identifying the variant responsible for a coronavirus case requires sending a positive sample to a lab to be sequenced, a process that often takes a few weeks after a person tests positive. And only a small share of cases are eventually sequenced.

That delay means that up-to-date data on variants is nonexistent, and the most recent data comes from particularly small sample sizes and is most likely to adjust downward or upward as more sequences come in. But researchers’ best estimates show that in recent weeks, states with the highest vaccination rates have seen significantly lower increases in the absolute number of cases compared to places where fewer people are vaccinated.

And even as Delta becomes the predominant variant in all states, that trend is likely to continue, according to scientists at Scripps Research. Researchers there developed and maintain outbreak.info, a project that tracks and visualizes Covid-19 genomic data.

In considering Delta’s continued trajectory in the United States, scientists point to the variant’s rise to dominance in other countries where it has been circulating longer. Those countries’ varying levels of vaccination have led to very different outcomes.

In India, where the variant was first detected, Delta fueled an immense surge, with case and death rates that experts say were vastly undercounted. India’s rise in cases began before even 1 percent of the population was fully vaccinated. Swamped hospitals turned away patients by the thousands, oxygen supplies ran out, and fires burned all night at cremation grounds as the death toll soared.

In the United Kingdom, however, Delta became dominant when a large share of the population had already been protected by vaccination. Cases have surged, but hospitalizations and deaths have remained low relative to previous peaks — including one driven by a variant that previously became dominant there, Alpha — because of vaccinations. In particular, Britain prioritized immunizing its older adults and others at high risk.

When the Delta variant became predominant in Britain several weeks ago, a lower share of all adults were fully vaccinated there than are fully vaccinated in the U.S. now. Covid-19 related deaths remain low and are expected to stay well below previous peaks in the U.S. because of relatively higher vaccination rates across the country.

But the slowdown of the U.S. vaccination campaign has prompted some concerns. It has been tough to persuade young people to get a shot, but the Biden administration is making a renewed push to sway them, recruiting YouTube stars and celebrities — most recently Olivia Rodrigo, the 18-year-old pop star with the nation’s No. 1 album — to share pro-vaccine messages with their followers.

Researchers aren’t sure yet how much hospitalizations in the U.S. will rise, in part because older and more vulnerable populations tend to be more vaccinated — nearly 80 percent of those 65 and older are fully vaccinated — and younger people, though more likely to be unvaccinated, tend to have less severe infections.

“Based on what we’ve seen in the U.K., we would expect the rate of hospitalizations to be lower than what we had seen in the previous waves,” said Karthik Gangavarapu, a computational scientist at Scripps Research, “but it’s still expected to be significant, unless we curb transmission.”