Adults who are recovering from a mild infection with the novel coronavirus have their antibody levels against the COVID-19 decline in the space of a few weeks, according to a recent study.
The researchers from the university of California at Los Angeles have followed for nearly three months for 34 individuals who have contracted the coronavirus, taking samples of their blood two or three times during this period.
The analysis of the samples indicates that the antibody levels drop by half in 73 days on average, barely two and a half months, according to a correspondence published in the medical journal New England Journal of Medicine.
Most of the patients studied have suffered only mild symptoms ; only two had to be given supplemental oxygen and none were placed on an artificial respirator.
Participants were between 21 and 68 years of age, and an average age of 43 years.
Concerns for vaccines
“These results raise a number of concerns, namely that humoral immunity against the SARS-CoV-2 may not be long-term in people with a mild form of the disease, which represent the majority of cases,” write the authors of the study.
Antibodies are proteins secreted by the immune system in response to an infection. Their function is to recognize and neutralize the pathogen. But their ability to fight the virus SARS-CoV-2, responsible for the disease COVID-19, has not yet been demonstrated.
However, the immune response of the organism is not measured only with the antibodies.
Immune cells, called T cells, could also play a protective role important against the COVID-19.
Despite this, the californian researchers believe that their findings ” call for caution “, particularly concerning the concept of herd immunity.
The decrease in antibody levels after a few weeks could “maybe” even put in question the sustainability of the vaccines, suggest experts.
The case of Sweden
At the end of April, the world health Organization has warned that there is currently “no evidence” that persons who have contracted for the first time the COVID-19, and which heal, are protected from a second infection.
It did not prevent the health authorities from Sweden, recently, to say that the people who have caught the COVID-19 are probably immune for at least six months, even if they do not develop antibodies.
Let’s remember that this country of ten million inhabitants is unusual in the world since the beginning of the pandemic, with the rules of containment are less strict than elsewhere.
The COVID-19 has done 5667 dead in Sweden so far, according to the count of the Johns Hopkins university.