Antibodies Fade Quickly in Patients Recovering From COVID-19

October 17, 2020

Antibody levels in the blood of patients who have recovered from coronavirus disease 2019 (COVID-19) decline rapidly during the weeks after their bodies have cleared the virus and symptoms have subsided.

Andrés Finzi, PhD, University of Montreal, Montreal, Quebec, and colleagues performed repeated analyses at 1-month intervals on 31 convalescent individuals to evaluate how the humoral responses against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike glycoprotein, including neutralisation, evolve over time.

All of the convalescent donors initially tested positive for SARS-CoV-2 by reverse transcriptase-polymerase chain reaction (RT-PCR) on nasopharyngeal specimens, with complete resolution of symptoms for at least 14 days before blood sampling. The average age of the donors (22 males and 9 females) was 46 years. The researchers collected plasma samples from each individual 6 weeks after symptom onset and 4 weeks after.

“We observed that the levels of receptor-binding-domain (RBD)-specific Immunoglobulin (Ig)G and IgA slightly decreased between 6 and 10 weeks after the onset of symptoms but that RBD-specific IgM levels decreased much more abruptly,” the authors wrote. “Similarly, we observed a significant decrease in the capacity of convalescent plasma to neutralise pseudoparticles bearing wild-type SARS-CoV-2 S or its D614G variant. If neutralisation activity proves to be an important factor in the clinical efficacy of convalescent plasma transfer, our results suggest that plasma from convalescent donors should be recovered rapidly after resolution of symptoms.”

Currently, recovering patients can’t donate blood until at least 14 days after symptoms have subsided.

“Our work shows that the capacity of the plasma to neutralise viral particles is going down during those first weeks,” said Dr. Finzi.

“While waiting for an efficient vaccine to protect against SARS-CoV-2 infection, alternative approaches to treat or prevent acute COVID-19 are urgently needed,” the authors wrote. “Transfusion of convalescent plasma to treat COVID-19 patients is currently being explored; neutralising activity in convalescent plasma is thought to play a central role in the efficacy of this treatment. Here, we observed that plasma neutralisation activity decreased a few weeks after the onset of the symptoms. If neutralising activity is required for the efficacy of convalescent plasma transfer, our results suggest that convalescent plasma should be recovered rapidly after the donor recovers from active infection.”


SOURCE: American Society for Microbiology