Almost two months after the start of the Covid-19 vaccination effort, US public health officials have another challenge on their hands: ensuring that the people who gave the first vaccine return to the second.
The initial data shows that most people are returning for the second attempt. Data from the Texas Department of Health Services showed that only 0.3 percent of the 1.9 million people vaccinated so far were late for their second injection – although another 7.5 percent are due.
In Oregon, 5 percent of people who received their first dose of the Pfizer-BioNTech vaccination are late for their second injection, according to state public health data.
But the researchers have cause for concern. Vaccines for other types of diseases can give a clue to the challenge that public health officials face. For the Shingrix shingles vaccine, about 25 percent of people taking the first dose do not show up for the second dose, according to Dr. Paul Offit, a vaccine researcher at the Children’s Hospital in Philadelphia.
“You must be chased for having to take your second dose,” he said.
It is not certain that everyone will be diligent in completing the vaccination process on schedule, despite scientific evidence that a booster injection makes coronavirus vaccines more than 90% effective in preventing symptomatic diseases.
“The vast majority of people who should receive their second doses have received them, but there are some who have not received them and have now passed the six-week mark in which it is recommended,” said Chris Van Deusen, spokesman for the Department of Health Texas State Services said in an email.
“We definitely want people to get their booster doses in time because they are important for boosting immunity,” he said.
And as more vaccines are launched in addition to frontline healthcare professionals and older Americans, there is concern that these numbers may grow. Offit said states, counties and health care providers will need to rely on a combination of newer technologies, such as smartphone notifications, along with older tactics, such as calls to make sure they get people’s attention.
“God only knows that retail pharmacies are good at this. The minute your prescription arrives, you receive the message and receive it again and again, ”he said.
The push is taking place in a public debate about whether to delay the second photos and focus on getting the first photos to as many people as possible. Congressman Ro Khanna, D-Calif., Sent a letter this week to Biden government officials urging them to consider switching to a single-dose strategy, an idea that many experts, including Offit, say are poorly designed because it is not as soon as Covid- 19 vaccines were tested. The immunization is weaker and may not last as long with a dose, said Offit.
The guidance of the administration and the Biden states is to complete the two-dose regimen.
The second dose is scheduled for about three weeks after the first dose of the Pfizer-BioNTech vaccine, and about four weeks for the Modern vaccine, according to guidance published last month by the Centers for Disease Control and Prevention. But the CDC also said that reinforcements could be administered up to six weeks later, if it were not feasible to obtain them beforehand.
The first doses of the Pfizer vaccine were administered on December 14, meaning that the recommended interval has recently ended for the second injection for these patients.
There may be a number of reasons why people did not receive the second injection, experts say, and there is still no good evidence on the main reasons. They can include limited offers, canceled appointments, fear of side effects, forgetfulness or difficulty navigating the appointment schedule.
Politics can also be a factor. Offit said he was concerned that some state governors were quietly lessening the emphasis on second doses. He said he spoke to public health officials who felt pressured to prioritize first doses, at least in part because these numbers are often highlighted in the media. He refused to identify the states.
“There is pressure to vaccinate as many people as possible so that their condition does not look as bad as others,” said Offit.
Not all states report data on how many people are late for the second dose, making it difficult for public health and medical experts to assess the amount of recovery states and healthcare providers need to make.
Florida reported the number of doses overdue in January, indicating that tens of thousands of people were late at the time. But the label may not have been meaningful under the eventual guidance of the CDC because that was before six weeks had passed since the first 14 December doses. In any case, Florida has finally stopped reporting the number.
Jason Salemi, an epidemiologist at the University of South Florida, said it is still difficult to know whether states are struggling or worrying. He said he was excited by the fact that, in recent days, Florida has administered more second doses than first.
“A little more thorough investigation would be needed to see if we should be concerned about this,” he said. “I hope they are at least collecting this information, analyzing it and following up.”
The Florida Department of Health did not respond to a request for comment.
Vaccine experts are concerned that people may not realize that a dose of Pfizer or Moderna injections will not be enough to fully protect them from the virus. Offit is specifically concerned that receiving just one dose of the mRNA vaccines, or waiting many months between doses, may facilitate the coronavirus mutation.
“One dose can make it easier to create variants, because the virus is injured with a lower immune response, not killed,” he said by email. “And when injured, he has a chance to escape.”