NEW DELHI: A majority of individuals recovering from mild or moderate Covid-19 develop a robustantibodyresponse that lasts for at least five months, according to a study published in the journal Science.
While most studies so far have found that antibodies to the novel coronavirus go away quickly, this new study conducted at the Icahn School of Medicine at Mount Sinai in New York found the opposite.
“The strength and duration of immunity after viral infection is important for informing decisions on public health preventive measures, for judging the effectivity of convalescent plasma for treating sick individuals and for predicting the efficacy of vaccines. A single study should not trigger a premature celebration — we need to watch carefully as more data helps us understand the natural history of Covid-19,” said SP Kalantri, professor of medicine at the Mahatma Gandhi Institute of Medical Sciences in Sevagram, Maharashtra.
The Mount Sinai study revealed that more than 90% of the people who were mildly or moderately ill produced an antibody response that’s strong enough to neutralise the virus for several months.
“Our data suggests that more than 90% of seroconverters make detectible neutralising antibody responses. These titers (levels) remain relatively stable for several months after infection,” the authors of the study said. A seroconverter is one that has or is undergoing production of antibodies.
The findings were based on the data of 30,082 individuals, who were screened within the Mount Sinai Health System from March to October.
The scientists used an antibody test called enzyme-linked immunosorbent assay (ELISA) to detect the tell-tale spike protein that enables the virus to attach itself to human cells and gain entry. The test detects the presence or absence of antibodies to SARS-CoV-2, the virus that causes Covid-19, and measures the level of antibodies.
The study found that of the 30,082 positive samples, the vast majority had moderate-to-high levels of anti-spike antibodies. The levels ranged from 1:80 for 690 individuals (2.29%) to 1:2,880 for 11,610 individuals (38.6%).
According to the researchers, this indicated that a moderate level of antibodies is retained by most people five months after the onset of symptoms.
The study has come as a breather after earlier research showed that antibodies decline rapidly. A recent study from Imperial College London also found that antibodies against Covid-19 declined rapidly in hundreds of thousands of people across England.
“The (Mount Sinai) study findings differ from a previous study from China that showed that a large number of individuals who recovered from SARS-CoV-2 infection had waning titers of antibodies within eight weeks of infection. That study also showed that in as many as 40% of asymptomatic individuals, antibodies disappeared after 8 weeks of infection,” said Kalantri.
A public health expert said that an elaborate study is needed to substantiate the findings of the Mount Sinai study.