U.S. Vaccinations Are Slowing. What’s to Blame?

As the country approaches 150 million vaccinated people, the pace of the rollout has been slowing, signaling a new phase of the campaign in which supply in many areas exceeds demand. The average number of people getting a first or single dose each day has fallen by about 50 percent from the peak on April 13.

Average share of United States population receiving a first dose per day, by manufacturer

Pfizer or Moderna
Johnson & Johnson
0 0.25 0.5%March 22May 3Johnson & Johnson paused
Source: Centers for Disease Control and Prevention | Note: Figures show a 7-day average based on the date shots were reported, rather than the date shots were given, so the pause announced on April 13 did not affect the data from that date. Johnson & Johnson vaccinations also appear in the data throughout the pause because vaccinations may be reported multiple days after they are given. Estimates for Pfizer and Moderna vaccinations include a small share of vaccinations with an unknown manufacturer.

Vaccinations fell sharply in the days after April 13, when health officials announced a pause on the Johnson & Johnson vaccine to investigate reports of rare side effects, and they have not fully recovered. Experts say the 11-day pause is partly responsible, but the data also shows a slowing uptake of the Pfizer and Moderna vaccines.

“It’s a factor, but not the major factor,” Dr. Cyrus Shahpar, the White House’s Covid-19 data director, said of the Johnson & Johnson pause.

The Johnson & Johnson vaccine has started to return across the country, but it’s too soon to say how much its use will rebound. A Survey Monkey poll by Boston Children’s Hospital shows that willingness to take Johnson & Johnson fell during and after the pause, especially among women, but that interest in getting the one-dose shot is slowly returning.

Health officials say the national deceleration was an inevitable part of the rollout, after reaching the people most eager to get their shots in most states. The decline is visible in the data for those seeking their first or second shots, but also for total doses administered, which peaked at slightly above three million shots a day, just before the pause took effect.

“The idea that this would be a linear increase and we would hit a million shots a day, two million shots a day, three million shots a day, four, four and a half, and then keep rising at that rate, we never really anticipated that,” said Ben Wakana, deputy communications director for the White House’s Covid-19 response team. “We believe we will continue vaccinating millions of people a day.”

A New York Times analysis of data from the Centers for Disease Control and Prevention shows more than a dozen states with flattening or falling Pfizer and Moderna first-dose vaccinations in early April.

These states include some that had opened up vaccination to all adults earlier in the year, such as Arkansas, Kansas and Oklahoma; Southern states with large rural populations like Louisiana and Mississippi; and places that were notably efficient early in their campaigns, like North Dakota and West Virginia.

Average share of state population receiving a first dose per day, by manufacturer

In some states, Pfizer and Moderna vaccinations were already declining before the pause on Johnson & Johnson began on April 13.

Source: Centers for Disease Control and Prevention | Note: Figures show a 7-day average based on the date shots were reported, rather than the date shots were given. As a result, Johnson & Johnson vaccinations appear in the data throughout the pause. Estimates for Pfizer and Moderna vaccinations include a small share of vaccinations with an unknown manufacturer.

In contrast, some states that opened up to all adults on April 15 or later, including California, Hawaii, Massachusetts, Rhode Island and Vermont, show a rising use of Pfizer and Moderna in the days after the Johnson & Johnson pause, indicating remaining demand. Most of these states have seen a subsequent decline.

In Connecticut, where the Johnson & Johnson vaccine had become popular, especially in mobile clinics, all three brands of vaccine were rising in use and then dropped off after the pause on Johnson & Johnson.

It’s hard to know with any certainty what role the pause played in the decline, said Josh Geballe, the state’s chief operating officer. “It surely didn’t help.”

“But we had always anticipated we would start to see a deceleration around late April,” he added, noting that more than two-thirds of the state’s eligible population had gotten a first shot.

“You start running out of people to vaccinate,” he said. “It would naturally start to slow down.”

Average share of the population receiving a first dose per day, by age group

Source: Centers for Disease Control and Prevention | Note: Figures show the date shots were given. The last five days of data are excluded because not all vaccinations on these dates have been reported yet.

C.D.C. data reveals that the declines since mid-April have been sharpest for those aged 18 to 64, who became eligible for a vaccine in most states last month. Just over 50 percent of this age group remains unvaccinated.

Health experts and officials say there’s lots of work to be done to reach those adults who haven’t yet gotten the vaccine.

Some who have not yet been vaccinated will refuse to ever get a shot, but others might have had trouble finding time to make an appointment, or have questions about safety or vaccine efficacy, said Dr. Nirav Shah, the director of the Maine Center for Disease Control and Prevention.

Officials across the country say they believe that there’s still a substantial portion of the population who will get a vaccine if given more support and more information from trusted messengers, like personal doctors.

“We need to be in the community, asking the community what works for them and keeping that presence,” said Dr. Karen Landers, Alabama’s assistant state health officer. “We are not giving up,” she added.

And this work to make vaccinations more convenient, to answer questions and get the message just right will take some time, Dr. Shah said.

“In no project in human history is the second half as fast as the first,” he said.