Since April, health care providers in France have routinely
given a third dose of a two-dose vaccine to people with certain immune conditions. The number of organ transplant recipients who had antibodies increased to 68 percent four weeks after the third dose from 40 percent after the second dose, one team of French
researchers recently reported.
But in the United States, there is no concerted effort by federal agencies or vaccine manufacturers to test this approach, leaving people with low immunity with more questions than answers.
The Centers for Disease Control and Prevention, the Food and Drug Administration, and the National Institutes of Health in fact
recommend even
against testing to find out who is protected. And academic scientists are stymied by the rules that limit access to the vaccines.
“There should be already a national study looking at post-transplant patients getting booster shots,” said Dr. Balazs Halmos, an oncologist at the Montefiore Medical Center in the Bronx, who led a study showing that some cancer patients did not respond to the vaccines. “It shouldn’t be our little team here in the Bronx trying to figure this out.”
An estimated 5 percent of the population is considered to be immunocompromised. The list of causes is long:
some cancers,
organ transplants, chronic liver disease, kidney failure and
dialysis, and drugs like Rituxan,
steroids and
methotrexate, which are taken by roughly
five million people for disorders from rheumatoid arthritis and psoriasis to some forms of cancer.
“These are the people being left behind,” said Dr. Jose U. Scher, a rheumatologist at NYU Langone Health who led a study of
methotrexate’s effect on the vaccines.
The third-dose approach has widespread support among researchers because there is clear precedent. Immunocompromised people are given booster doses of vaccines for hepatitis B and influenza, for example.
Several studies have
indicated that a third coronavirus vaccine dose
might succeed in patients who did not have
detectable antibodies after the first or second dose. But research has lagged.
Moderna is
gearing up to test a third dose in 120 organ transplant recipients, and Pfizer — which produces some immunosuppressant medications — is
planning a study of 180 adults and 180 children with an immune condition.
The N.I.H. is
recruiting 400 immunocompromised people for a trial that would track their levels of antibodies and immune cells for up to 24 months, but has no trials looking at a third dose.
“It takes time, unfortunately, especially as a government agency,” said Emily Ricotta, an epidemiologist at the National Institute of Allergy and Infectious Diseases. “We have to go through a lot of regulatory and approval processes to do these sorts of projects.”
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