COVID-19 Vaccination Can Clear this Coronavirus

CanSinoBio Biologics Inc. recently announced an article titled "Successful clearance of persistent SARS-CoV-2 asymptomatic infection following a single dose of Ad5-nCoV (Convidecia™) vaccine," published in the medical journal Signal Transduction and Targeted Therapy, revealed for the first time the role of vaccination in clearing the coronavirus infections.

The prevalence of asymptomatic COVID-19 infection accounts for 40%-45% of cases.

On April 7, 2023, CanSinoBio reported in a media release in cases of long-term asymptomatic infection, Ad5-nCoV vaccination can generate a rapid and robust antibody response and coordinate B-cell and cTfh cell immune responses to facilitate subsequent virus clearance.

In addition, vaccination-induced antibodies exhibited broad-spectrum neutralizing activity and immune-persisting activity against various virus strains.

This study's highlights include, but are not limited to, the following:

• After Ad5-nCoV vaccination, humoral immune responses were effectively enhanced, while antigen-specific CD4 and CD8 T cell responses were modestly improved, suggesting that enhanced humoral responses after primmunizationnation play a role in clearing viral RNA and treating persistent SARS-significant significant role in infection,
• And an essential role of B cells and cTfh cells in antibody production, both nAb and RBD-specific IgG titers were positively correlated with RBD B cells, ASC and cTfh,
• Following vaccination, the frequencies of SARS-CoV-2 RBD B cells and ASCs increase rapidly, peaking at 2–6 weeks post-vaccination, respectively,
• Furthermore, cTfh cells exhibit similar kinetics to ASC,
• In contrast to strongly enhanced antibody responses, SARS-CoV-2-specific CD4+ and CD8+ T cells did not increase significantly after vaccination.

Taken together, this study reveals that prolonged asymptomatic infection with SARS-CoV-2 may be attributed to impaired immune activation, manifested by low levels of initial inflammation, interferon, and weak antibody responses, markedly reduced cTfh, and specific CD4+ and CD8+ T cell responses were insufficient, wrote the company.

CanSinoBio's Convidecia™ is a novel recombinant viral vector vaccine for COVID-19, and the inhaled version, Convidecia Air™, was approved as a booster dose on September 4, 2022. 

These COVID-19 vaccines are available in about ten countries as of April 12, 2023.