The willingness of the American public to get a Covid vaccine is reaching a saturation point, according to a new national poll. This is yet another indication that achieving widespread immunity in the United States is becoming increasingly difficult.

Only 9 percent of respondents said they hadn’t received the shot yet, but they intended to, according to the poll published in the April issue of the Kaiser Family Foundation’s Vaccine Monitor. And with federal approval of the Pfizer vaccine for teens 12-15 years old imminent, parents’ willingness to get their children vaccinated is also limited, the survey found.

Overall, just over half of respondents said they had received at least one dose of the vaccine, which is in line with data from the Centers for Disease Control and Prevention.

“We are in a new phase of vaccine demand,” said Mollyann Brodie, executive vice president of Kaiser’s Public Opinion and Survey Research Program. “There won’t be a single strategy to drive demand from all of the remaining people. There will have to be a lot of individually targeted efforts. The people who are still on the fence have logistical barriers, information needs and many do not yet know whether they are authorized. Any strategy could get a small number of people to get vaccinated, but all in all, it could be very important. “

As more scientists and public health experts conclude that the country is unlikely to reach the herd immunity threshold, the Biden government has stepped up efforts to reach those who still hesitate. On Tuesday, the government announced steps to encourage more pop-up and mobile vaccination clinics, and to distribute the recordings to general practitioners and pediatricians, as well as local pharmacies.

The survey also found that confidence in the Johnson & Johnson vaccine had taken a significant blow after the 10-day hiatus, while authorities investigated rare cases of life-threatening blood clots in people who took it. While 69 percent of respondents said they had confidence in the safety of the vaccines manufactured by Pfizer and Moderna, only 46 percent believed the vaccine from Johnson & Johnson was safe. Among adults who were not vaccinated, one in five said the news of the Johnson & Johnson shot had caused them to change their minds about a Covid-19 vaccine.

The poll found that some of the most prominent Republicans were making some progress. In this group, 55 percent said they had or intended to get a shot, up from 46 percent in March. The percentage who will “definitely not” receive the vaccine also drops from 29 percent in March to 20 percent.

The results were based on telephone surveys of a nationally representative sample of 2,097 adults from April 15 to 29.

The so-called “wait and see” group – people looking for more information before making a decision – was within 15 percent, constant from 17 percent in March. The proportion of people who said they were only vaccinated when required by employers or schools was 6 percent, compared with 7 percent in March.

The Pfizer vaccine is expected to be approved within a few days for children ages 12-15. Among parents surveyed, three in ten said they would vaccinate their children immediately, and 26 percent said they wanted to see how the vaccine works. These numbers largely reflected the zeal with which these parents themselves sought vaccination.

Updated

May 6, 2021, 9:42 a.m. ET

Similarly, 18 percent said they would only do this if a child’s school required it, and 23 percent said they would definitely not have their children vaccinated.

A consortium of universities that includes Harvard, Northeastern and Rutgers conducted online surveys during the pandemic and recently focused on parents. The group’s most recent poll, conducted in April and reaching 21,733 adults in 50 states, found that the gap between mothers and fathers when it comes to the vaccine for children had widened.

The resistance of fathers seems to be weakening somewhat and has fallen from 14 percent since February to 11 percent. But more than a quarter of mothers, the researchers say, still say they are “extremely unlikely” to vaccinate their children. Both sexes are more resistant to the vaccine in younger children than in teenagers. Other research shows that mothers tend to have more influence on the final decision than fathers.

Parents’ answers could change over time, experts say. Just as adults were far less hesitant last summer, when the vaccine was still a concept, parents who were interviewed a few weeks ago when the upcoming approval for children under 16 had not been fully discussed could possibly be more likely to point to a hypothetical situation than responding to a reality.

However, pediatricians and others who are believed to be trusted sources of information are already aware that there is still much work to be done to increase the confidence of vaccines in this newest cohort.

Dr. Sean O’Leary, a Denver pediatrician who is vice chairman of the American Academy of Pediatrics’ infectious diseases committee, predicted that just as adults had flooded Covid vaccine providers in the first few weeks of distribution, parents and pent-up teenagers would too pounce on it at the beginning.

Dr. However, O’Leary, who often speaks to pediatricians about how to motivate patients to accept vaccinations, fears the slowdown will inevitably occur. To convince reluctant parents, he said, “We need to have the vaccine available in as many places as possible.”

He added, “When parents and patients are in the pediatrician’s office and the doctor can say, ‘Hey, I have it,’ it can kick start saying, ‘Let’s go ahead and do this.” ”