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Reinfection with Sars-CoV-2, the source of the Covid-19 pandemic, is rare; however, according to the scientific community today, it does exist. Why do we get reinfected when others seem immune? Researchers are working to identify two sides of the same coin. Inserm and its Detox Channel take stock of the still incomplete data on the subject.
Several peer-reviewed case studies published in scientific journals confirm this: re-infections with the new coronavirus at the origin of pandemic from COVID-19 are possible. However, the data available on the subject are still fragmented and the number of cases documented with sufficient rigor is very limited. In the current state of knowledge, most scientists therefore agree that the phenomenon of reinfection remains rare.
However, it seems necessary to continue research on this topic, and more generally onimmunity, in order to understand it better and to grasp the possible immunological characteristics e genetics common that could exist among reinfected patients. To see more clearly, Detox Channel, with Frédéric Altare, Inserm researcher and immunologist at the Center de recherche en Oncology and Immunologie Nantes-Angers (CRCINA), take stock of what we know and what we are still trying to know about re-infections and immunity in the context of the pandemic.
A shy optimism quickly thwarted
Since its inception, the issue of reinfection has arisen. In the spring of 2020, a study published in Nature Review Immunology carried out on animal models showed that reinfecting non-human primates some time after first exposure a SARS-CoV-2, these have not developed any symptom of illness. Also, no signs of replication of virus has been observed in nasopharyngeal swabs. The conclusions of this study were therefore cautiously optimistic, suggesting some degree of immunization against the virus after a first infection.
At the same time, the studies describing the early cases of reinfection potential in humans have appeared. However, they had a number of limitations. For example, a study published in theAmerican Journal of Emergency Medicine documented the case of an 82-year-old patient admitted to hospital in April. After 28 days in intensive care, he was able to return to his home after two test the PCR negative. Ten days later, theemergency the new symptoms forced him to go to hospital services.
Reinfection has not been confirmed, however, the researchers estimated that traces of the virus may have remained in her body between her two hospital visits and that PCR tests could have given false negative results. Other publications have reported similar situations, without even being able to prove that it was reinfection.
Reinfections are confirmed
More recently, the teams have managed to overcome these limits and have confirmed the possibility of reinfection. A study published in Clinical infectious diseases then it showed that one patient had been infected twice at 142-day intervals. He was asymptomatic the second time. These results were made possible thanks to the analysis of genome viral content in samples collected during the first and second infections and their comparison with the SARS-CoV-2 sequences on the GISAID platform. The researchers showed that these were two tensions different and that the patient was then infected twice, with two distinct genetic forms of SARS-CoV-2.
Of these few strictly confirmed cases of reinfection, only one, described in October 2020 in The Lancet, had presented more severe symptoms the second time, after reinfection.
Be able to identify profiles that could be reinfected
If reinfected people may have a defect immune response which has yet to be demonstrated, the available data therefore suggest that a form of immunity, even partial, is established following a first contact with the virus. It remains to be seen how long this protection can last and how effective it is in the long term. In fact, from many questions remain regarding the immune response to SARS-CoV-2.
The results of current vaccine studies, which require a precise analysis of the volunteers’ immune response and their risk of being infected by receiving a vaccine candidate, might make it possible to see more clearly on these questions. They should pave the way for a more precise characterization of the immune response to Covid-19 and the phenomenon of reinfection, in particular by identifying the profiles most susceptible to it and for what reasons.
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