Covid-19 : Natural immunity versus vaccine immunity

It should not be necessary to write an article to demonstrate the superiority of natural immunity over vaccine immunity, but it is necessary in view of the many underhanded attacks that tend to make artificial immunity seem more effective. Furthermore, it is officially recommended to vaccinate people who have already been infected with Covid-19. Survivors of the 2003 SARS-CoV have cellular immune memory more than 17 years after infection. Numerous studies have explored humoral (antibody) and cellular immunity to SARS-CoV-2 after Covid-19 infection: it persists for at least one year (and even 14 months) in a robust manner in convalescents and would be of better quality than vaccine immunity: natural antibodies are more potent, have a broader spectrum, and are able to evolve against variants more efficiently than vaccine antibodies. These _in vitro _studies are confirmed by the protection against reinfections conferred by a primary infection, particularly in early and highly vaccinated countries such as Israel and the United Kingdom. Vaccination of a primo-infected person could also decrease the effectiveness of his natural immunity against future reinfections. Neutralizing antibodies may not be the correct correlate of protection against infection, as high levels of neutralizing antibodies have been found in patients with severe Covid, and vaccinated patients, who are more susceptible to reinfection than primary patients, have antibody levels equivalent to or higher than those observed in primary patients. The neutralizing capacity of these antibodies directed against the membrane spike protein is measured _in vitro_. This neutralizing capacity may be different _in vivo_; it may be diminished by the presence of antibodies that facilitate infection; and antibodies are produced against other viral antigens during natural infection. Cellular immunity could be the right correlate of protection and this type of response could be of lower quality in vaccinated subjects. In addition, vaccination of convalescent subjects could be risky: more systemic adverse events are observed in convalescent subjects than in naïve subjects after the first dose of vaccine. Vaccination may decrease the ability to respond to future variants. It could also have a non- specific effect of remodeling the innate immune response by decreasing the potential response to other viruses or cancers and by modifying the course of inflammatory and autoimmune diseases. The natural immunity of a population should therefore be explored before proposing vaccination: up to 50% of the population may have been infected in some countries.