© Alex McIntyre / The Greeley Tribune / Reuters
WASHINGTON – US government scientists are battling calls for one-dose regimens for two Covid-19 vaccines designed to be administered with two injections, saying there is insufficient evidence that a single dose provides long-term protection.
“It is essential that these vaccines are used as authorized by the FDA to prevent Covid-19 and related hospitalizations and deaths,” Peter Marks, director of the center that supervises vaccines at the Food and Drug Administration, told The Wall Street Journal.
The FDA approved at the end of last year a two-dose vaccine regimen from Moderna Inc. and a partnership between Pfizer Inc. and BioNTech SE. More recently, it approved the use of a single dose regimen for a Johnson & Johnson vaccine.
Some scientists and lawmakers have called for a switch to a single dose regimen for all vaccines, citing preliminary studies showing that one dose can be effective. They say that switching to a dose will allow the United States to accelerate the pace of vaccinations.
In a March 2 letter to Interim Secretary for Health and Human Services, Norris Cochran, seven Congressional physicians urged the department “to consider issuing a revised emergency use authorization as soon as possible” that could lead to use single dose of Pfizer and Moderna vaccines.
“Last week, the United States passed a worrying milestone of more than 500,000 COVID-19-related deaths,” said the letter, signed by lawmakers including Rep. Andy Harris (R, Md.) And Rep. Gregory F. Murphy, ( R., NC). “These are impressive statistics, and anything we can do to help prevent new tragedies – to further protect the public health and safety of the American people – must be fully employed.”
In interviews, senior scientists from the FDA government and the National Institutes of Health said that such a change is not justified, saying the evidence used to approve the Pfizer and Moderna vaccines was based on two doses.
These scientists said that a dose may offer short-term protection, but long-term protection is a question mark.
“You would be flying blind if you only used one dose,” said a senior scientist and adviser to President Biden. “If you are going to do anything other than follow the studies shown to the FDA, show me that this unique effect is durable.”
Another senior US government doctor said vaccination durability is especially important when more resistant strains of Covid-19, including those from the UK and South Africa, are appearing in the U.S.
“We think it is better to get people to the highest possible level of immunity,” said the doctor.
The doctor added that the pace of vaccinations is accelerating with Merck & Co.’s recent decision to help produce the J&J vaccine.
“We will soon have a good stock of vaccines,” said the doctor.
Asked to comment on Saturday, Moderna in a statement said that “in ongoing clinical studies and real-world evidence assessment, we do and will analyze many secondary issues, potentially including this issue” from a single dose regimen.
Pfizer did not respond to a request for comment. The company said earlier that it has no data for the single-dose approach.
Paul A. Offit of Philadelphia Children’s Hospital, who served on the FDA advisory panel that recommended the use of the Pfizer and Moderna vaccines, said these clinical trials “found a level of neutralizing antibodies [with one dose] this was significantly less than that obtained with two doses ”.
FDA Advisory Panel Chairman Arnold Monto also said that the two-dose regimen is best for the Pfizer and Moderna vaccines. Dr. Monto, a public health doctor at the University of Michigan, emphasized the need for two doses to combat Covid-19 variants.
“We have information about a two-dose strategy,” said Dr. Monto. “We need high levels of antibodies at these doses to deal with the variants.”
Others who hold similar views in the U.S. government are famed infectious physician Anthony Fauci and Andy Slavitt, a senior adviser at the White House to Covid-19’s response. Slavitt said it would be a mistake for the US government to be persuaded by just one study.
University of Minnesota epidemiologist Michael Osterholm said in testimony on Thursday before the Minnesota legislature that the United States should consider postponing second doses so that more people can get their first injections.
“We could vaccinate more people in our group over the age of 65,” he said. “I think the data will prove that, in fact, it is a very effective way of doing this.”
Two weeks ago, researchers in Israel reported that a dose of the Pfizer vaccine was 85% effective in preventing symptomatic diseases 15 to 28 days after inoculation.
In the UK, the government has chosen to stretch the supply of vaccines by delaying a second dose by up to 12 weeks in an attempt to reach more people.
British researchers released preliminary data in the past few days saying that either of the two vaccines – from Pfizer and AstraZeneca PLC – reduced the risk of hospitalization among people over 70 by 80%, compared with people of similar ages without vaccination.
AstraZeneca is still conducting a study in the United States of its vaccine, which has not yet obtained authorization from the FDA.
Write to Thomas M. Burton at [email protected]
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