Moderna's vaccine against covid-19 generated antibodies that persisted 90 days after inoculation, according to a study of 34 participants from the start of clinical trials and published on Thursday in the New England Journal of Medicine.
The duration of protection could be longer, but these are the first data in a period of several months validated independently.
Participants will be followed for 13 months to verify longer-term protection, the authors say.
Researchers from the National Institutes of Health evaluated the level of two types of antibodies against the coronavirus 90 days after the second dose of the vaccine, which in turn was administered 28 days after the first.
They observed an expected slight decrease in antibody level in vaccinated participants, but to a degree that remained higher and above the natural immunity revealed in patients who were infected with COVID
-19 and recovered.
No serious side effects were seen in the test subjects in the so-called phase 1 trial, which began in March.
Antibodies are just one component of the immune response, along with B (immune memory, antibody production) and T (which kill infected cells) lymphocytes.
The researchers note that the data on immune memory cells is not yet known.
Anthony Fauci, director of the Institute of Infectious Diseases, recently told AFP that he was "sure" that the immune memory created by the vaccine would last for some time.
"We do not know if it will be one, two, three or five years, we do not know," he said. Only time will tell.
"It's pretty positive news overall," Benjamin Neuman, a professor at Texas A&M University, told AFP on Thursday, referring to the new study, noting that even in the elderly the immune response remained "reasonably strong."
The topic of vaccination divides opinions. Some believe that it is the path back the normality before covid
-19, others are highly skeptical that the vaccines have been developed in such rush, and doubt that the testing and trials would be sufficient to provide their safety to humans.