Studies have found that SARS-CoV-2 immunity can last for at least 8 months

How long does immunity to Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) last after the initial infection? This is one of the important and difficult questions scientists are addressing today. A complete understanding of this core issue will have a significant impact on the future of public health, the course of the pandemic, and the effectiveness and longevity of future vaccines.

Persistent immunity to SARS-CoV-2, the causative agent of 2019 coronavirus disease (COVID-19), has been questioned due to the decline in serum antibodies during the recovery phase. However, functional immunity is mediated by long-lived memory T cells and B cells.

A new study by researchers at Monash University in Australia found that people infected with COVID-19 showed sustained protection against reinfection for at least eight months.

Research published in open source medRxiv* Preprint server, It provides solid evidence of the long-term potential of the vaccine.

Although some antibodies appear to decline over time, the body has the ability to remember the virus and produce the reactions needed to prevent serious illness. Experts believe that this type of immunological memory can last for years.

the study

The number of cases of COVID-19 is skyrocketing, and many companies and schools have reopened as blockade restrictions around the world have been relaxed, creating a second wave of infection in many countries.

To date, more than 60.49 million people have been infected and more than 1.42 million have died.

Some studies have shown that the antibody response declines within 3 months of being infected with COVID-19.

In the current study, researchers aimed to determine the longevity of SARS-CoV-2 specific memory B cells in patients with COVID-19.

To reach research results, researchers used a unique set of receptor-binding domain (RBD) and nucleoprotein (NCP) antigens to characterize the SARS-CoV-2-specific memory B cell compartment. I made it clear.

The team recruited 25 COVID-19 patients and collected 36 blood samples from day 4 to day 242 after infection. They measured the response of systemic memory B cells to SARS-CoV-2 infection.

From vaccination studies in mice and humans, the team emphasized that local systemic memory B cells differ in phenotype. Influenza-specific memory B cells have also been shown to persist in the lungs of mice and play an important role in protection from reinfection.

“As our knowledge of SARS-CoV-2 and human lung immunology evolves, we will gain insight into what is needed for a protective response against this respiratory virus. However, the establishment of systemic immunity is severe systemic. We propose to prevent sex COVID-19 and suggest that reinfection may be limited to mild or asymptomatic upper respiratory tract infections, “the researchers explained in the study.

Memory B cells

Circulating RBD and NCP-specific memory B cells were detected early after infection and persisted for more than 242 days after onset of symptoms.

In addition, early after exposure, Ag-specific cells expressed immunoglobulin M (IgM) over time, followed by immunoglobulin G (IgG) antibody predominance.

Antibodies to the virus began to decline 20 days after infection. However, all patients continued to retain memory B cells that recognized one of the two components of SARS-CoV-2, the spike protein and the nucleocapsid protein. These virus-specific memory B cells were detected by 8 months after infection.

Studies of SARS-CoV-2 specific memory B cells have the potential to be used as backup markers for humoral immunity in vaccination studies.Currently, COVID-19 vaccine trials are SARS-CoV-2 specific and Neutralizing antibody As a marker of vaccine efficacy.

The results of the current study provide a glimpse of the hope that candidate vaccines may provide long-term protection against SARS-CoV-2. IgG memory B cells continue to exist as antibody levels decrease as the immune response contracts, indicating that SARS-CoV-2 infection causes long-term humoral immunity.

The authors said the findings give hope Effectiveness of Vaccine against the virus.

“These results are important because they clearly show that patients infected with the COVID-19 virus have immunity to the virus and the disease,” said Menno van Zelm, an associate professor at Monash University. Stated.

“This is a black cloud of potential protection provided by the COVID-19 vaccine, and as one or more vaccines are developed, they provide long-term protection. Gives the real hope, “he added.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.