Researchers at Tel Aviv University in Israel found that the antibody response of symptomatic Covid-19 patients declines over a period of six months after recovery, as per the pre-print version of the paper on the server medRxiv.
The researchers analysed the B cell response — lymphocytes that originate in the bone marrow and help in eliminating free foreign invaders by enhancing immune responses against them — in response to SARS-CoV-2 and noted that it persists only for six months.
According to lead author Yariv Wine and the team, these findings point to the persistence of humoral memory in patients who have recovered from coronavirus disease 2019.
However, the researchers say whether or not the persistence of SARS-CoV-2-specific memory B cells is correlated with future protection in the absence of serological memory still needs to be determined.
The authors suggest that this question should be investigated once samples from patients who have been convalescent for one year become available.
Recent studies reporting on the isolation of RBD-specific B cells tried to elucidate the composition of neutralising antibodies.
Still, information regarding the dynamics of antibodies and their association with RBD-specific B cells in recovered Covid-19 patients is lacking, the researchers mentioned in their study.
The authors said this information would help researchers assess the breadth of humoral memory and whether this contributes to long-lasting serological and cellular memory.
“It is imperative to determine the persistence of humoral memory in Covid-19 recovered patients as it will help to evaluate the susceptibility of recovered patients to re-infection,” said the team.
The team found that the RBD-specific antibody titers declined over six months following symptom onset, pointing to decay in serological memory over time.
By contrast, RBD-specific memory B cells were found to be stable during the six-month period.
“These aspects should be further investigated in follow up temporal studies when samples from recovered patients one year following the onset of symptoms will be available,” concluded the team.