Four months after having had a mild Sars-CoV-2 infection, which healed without any treatment, a man has again tested positive but this time for the new South African variant. This time the man developed acute respiratory distress syndrome that required resuscitation by intubation and mechanical ventilation. Indeed this case clearly shows that the issue of immunity to SARS-Cov-2 and its duration is far from settled and more studies are still needed to reach a final verdict.
The team of the intensive care and resuscitation unit of the Louis-Mourier AP-HP hospital, led by Pr Jean-Damien Ricard of the University of Paris and Inserm, reported the first serious case of a patient reinfected with the South African 501Y.V2 variant several months after initial infection with SARS-CoV-2. This first case of reinfection with the South African variant was published in the journal Clinical Infectious Diseases on February 10, 2021.
Herd immunity now appears to be the only possible solution to the Covid-19 epidemic. However, questions remain about the duration and robustness of immunity to this coronavirus. Cases of reinfection by the virus after an initial episode have been described, but to date remain relatively rare. The recent appearance of new variants with mutations that offer certain selective advantages such as greater infectiousness increased virulence, and the ability to bypass the immune system raises new concerns.
These new variants, known as the “English,” “South African,” or “Brazilian,” depending on the country where they were first described, are currently associated with further increases in Covid-19 incidence and mortality. Fears about the possibility of reinfection or infection with these new variants are beginning to surface, despite vaccination.
No longer sure about natural Immunity
The team of Professor Jean-Damien Ricard, head of the intensive care medicine and resuscitation department at Louis-Mourier AP-HP Hospital, recently treated a 58-year-old patient with no significant comorbidities who had in September 2020, a mild first episode of Covid-19 (moderate fever and respiratory distress). This first episode had resolved spontaneously and recovery was confirmed by two negative PCR tests in December 2020.
In January 2021, the patient was readmitted to the emergency department of the Louis-Mourier AP-HP hospital for a recurrence of fever with respiratory distress. The SARS-Cov-2 PCR test was again positive, and sequencing of the virus, performed in the virology department led by Pr Diane Descamps at Hospital Bichat-Claude-Bernard AP-HP, showed the presence of mutations characteristic of the South African 501Y.V2 variant. The patient rapidly developed an acute respiratory distress syndrome requiring intensive care with intubation and mechanical ventilation. He had no biological signs of immunosuppression.
SARS-CoV-2 serology at the beginning of hospitalization was positive, suggesting that the immunity developed after the initial infection did not prevent reinfection with the South African variant. The virus responsible for the first infectious episode was not sequenced. However, the occurrence of the first infection one month before the first report of the 501Y-V2 variant in South Africa, and three months before its first reporting in France, ruled out the possibility of a recurrence of the first infection.
Reinfections despite the presence of antibodies
Although epidemiological and experimental data suggest that an initial infection is capable of inducing satisfactory protective immunity for at least 6 months, proven cases of reinfection have been reported despite the presence of neutralizing antibodies in the blood.
The South African 501Y-V2 variant has spread rapidly around the world since December 2020. It is characterized by the presence of mutations in the regions coding for the Spike protein, making it more infectious. The effect of these mutations on the efficacy of the vaccine is not yet clear.
Pending further scientific data to better assess the cross-immunity and efficacy of the vaccine against the new CoV-2-SARS variants, extreme caution continues to be warranted and strict adherence to social distancing guidelines even for those previously infected or already vaccinated.