COVID Antibodies Remain Stable – or Even Increase – 7 Months After Infection

The SEROCOV study also provides evidence that pre-existing antibodies against the common cold coronavirus may be protective.

Levels of IgG antibodies to SARS-CoV-2 Spike protein remain stable or even increase seven months after infection, according to a follow-up study in a cohort of health professionals coordinated by the Barcelona Institute for Global Health (ISGlobal), an institution supported by the “la Caixa” Foundation, in collaboration with the Hospital Clinic of Barcelona. The results, published in Nature Communications, also support the idea that pre-existing antibodies against the common cold could protect against COVID-19.

To predict the evolution of the pandemic and develop effective strategies, it is critical to better understand the dynamics and duration of immunity against SARS-CoV-2, as well as the possible role of pre-existing antibodies against the coronaviruses that cause a cold. With this goal in mind, the team led by ISGlobal researcher Carlota Dobaño followed a cohort of health professionals at the hospital clinic (SEROCOV study) from the start of the pandemic, to monitor the levels of antibodies to various SARS-CoV-2 antigens over time. . “This is the first study to evaluate antibodies to such a large panel of SARS-CoV-2 antibodies over 7 months,” Dobaño says.

The research team analyzed blood samples from 578 participants taken at four different times between March and October 2020. They used Luminex technology to measure the level and type of IgA, IgM or IgG antibodies against 6 different SARS-CoV-2 in the same sample. antigens and the presence of antibodies to the four coronaviruses that cause the common cold in humans. They also analyzed the neutralizing activity of antibodies in collaboration with researchers from the University of Barcelona. The research was funded by the European innovation network EIT Health.

The results show that most infections among health professionals occurred during the first wave of the pandemic (the percentage of participants with SARS-CoV-2 antibodies increased only slightly between March and October – from 13.5% to 16.4%). With the exception of IgM and IgG antibodies to the nucleocapsid (N), the rest of the IgG antibodies (including those with neutralizing activity) remained stable over time, confirming the results of other recent studies.

“Surprisingly, we even saw an increase in IgG anti-Spike antibodies in 75% of participants from month five, without any evidence of re-exposure to the virus,” said Gemma Moncunill, co-senior author of the study. No reinfections were observed in the cohort.

As for antibodies to human common cold coronaviruses (HCoV), the results suggest they could provide cross-protection against COVID-19 infection or disease. People infected with SARS-CoV-2 had lower levels of HCoV antibodies. In addition, asymptomatic subjects had higher levels of anti-HCoV IgG and IgA than those with symptomatic infections. “While cross-protection by pre-existing immunity to cold coronaviruses has yet to be confirmed, this could help explain the wide disparities in susceptibility to the disease within the population,” Dobaño said.

Reference: “Seven-month kinetics of SARS-CoV-2 antibodies and protective role of preexisting antibodies against seasonal human coronaviruses on COVID-19” by Ortega N, Ribes M, Vidal M, et al, Aug 6, 2021, Nature Communication.
DOI: 10.1038/s41467-021-24979-9