Immunity

Although SARS-CoV-2 is a new coronavirus, the majority of people have already been exposed to other seasonal coronaviruses. Having been infected by a seasonal coronavirus does not seem to protect against SARS-CoV-2, but only reduces the risk of developing a severe form of the illness. The origin of this possible relative cross-protection between coronaviruses is […]

In the early stages of infection by SARS-CoV-2 we mainly develop antibodies targeting the N protein (nucleocapsid, responsible for organisation of the viral genome) and the S protein (spike, responsible for the binding of the virus to the cell). Some of these are neutralizing, meaning that they target the spike and block its interaction with […]

The duration of immune memory after SARS-CoV-2 infection remains uncertain. Since this virus emerged only recently, there are no existing studies on long-term immunity. Immune memory comes from  B lymphocytes and T lymphocytes  (memory B and T cells) and antibodies specifically directed against the pathogen. Effective long-term protection does not necessarily involve a strong response […]

Following an infection, mature B lymphocytes produce antibodies that target the pathogenic agent but have a limited life span. However, some of them remain in germinal centres (lymph nodes, spleen) where they multiply and continue to refine their antibody qualities. Their life span is longer: these are the memory B lymphocytes that are called upon […]

The human immune system is made up of innate immunity and adaptive immunity. Innate immunity is not specific to invading pathogens, but allows an immediate response in the case of any aggression. The adaptive immune response is specifically directed against a pathogen, allowing immune-memory to take place, but has a slower reaction time. It is […]

Certain sectors of the population are more at risk during the COVID-19 epidemic. This is especially true of pregnant women, amongst whom there are more severe cases than in other people of the same age. The foetus protects itself from pathogens through the transfer of maternal antibodies (IgG) via the placenta. This transfer of antibodies […]

It has now been established that following SARS-CoV-2 infection, we efficiently generate antibodies against the virus. Some of these, the neutralizing antibodies, have the potential to block the binding of the virus to a target cell, but it has not yet been clearly established if they can give protection against new infection by the same […]

Could the immune response that protects us against common coronaviruses (HCoVs) prevent infection by SARS-CoV-2? To answer this question, a team of British researchers at the Francis Crick Institute, London, has developed an efficient test (flow cytometry) which allows the presence of antibodies targeting the spike (S) protein of the virus to be evaluated. This […]

Since the beginning of the epidemic, there have been numerous questions raised concerning antibody responses against SARS-CoV-2. What levels of antibodies are necessary to give protection against reinfection, and how long will such protection last? Although we have assembled a great deal of data relating to critical cases of COVID-19, we don’t know as much […]

Recent studies carried out in rhesus macaques have shown that a natural infection as well as several candidate vaccines could effectively protect against reinfection by SARS-CoV-2. This protection is correlated, inter alia, with levels of “neutralizing” antibodies that stop the virus interacting with its target cell. But specific immunity is made up of the humoral […]