SIB #465- Natural Immunity Versus Vaccine-Induced Immunity

The Study: Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections

Overview: This paper is a very straightforward, retrospective study out of Israel which compares three groups: 1) Fully vaccinated subjects with NO HISTORY of prior COVID infection, 2) previously infected individuals who had not been vaccinated, and (3)  previously infected infected individuals who had also received a single vaccine dose.                                                                                                                              

Key Points:         

·         The researchers evaluated for four different outcomes: a) SARS-CoV2 Infection, b) Symptomatic Disease, c) COVID related Hospitalization and d) COVID Related Death. 

·         In terms of relatively recent immunization  (Infection/ Vaccination) between Jan-Feb 2021) , Group 1 subjects (fully vaccinated/No prior history of COVID infection) were 13 times as likely to contract COVID with the Delta variant as those unvaccinated subjects in Group 2 who had achieved natural immunity through relatively recent  infection (Jan/Feb 2021).  

·         Fully vaccinated subjects who experienced “breakthrough” infections in Group 1 also showed significantly increased risk for symptomatic disease compared to those with “natural” immunity in Group 2 who happened to become re infected. 

·         Vaccine recipients with no prior history of infection “were also at a greater risk for COVID-19-related-hospitalizations compared to those that were previously infected.” 

·         Both vaccine recipients (Group 1) and those with natural immunity only (Group 2) demonstrated waning protection over the entire course of the study however subjects in Group 1 (vaccine only) were still nearly six times (5.96) as likely to experience breakthrough infection and more than seven times (7.13) as likely to experience symptomatic disease.

·         “Individuals who were both previously infected with SARS-CoV-2 and given a single dose of the vaccine (Group 3) gained additional protection against the Delta variant.” (Parenthesis and emphasis ours)

Author’s Conclusions: “This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity.” (emphasis ours)

Reviewer's Comments: Interesting study that will no doubt receive a lot of criticism because of the controversial findings. NOTE: This study is NOT anti vaccination per se but rather may be highlighting some early findings in the differences between how a immunity is conveyed via mRNA vaccination versus exposure to the whole virus which occurs following natural infection. 

Reviewer:  Mark R. Payne DC

Reference: Sivan Gazit, Roei Shlezinger, Galit Perez, Roni Lotan, Asaf Peretz, Amir Ben-Tov, Dani Cohen, Khitam Muhsen, Gabriel Chodick, Tal Patalon Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections. Published in medRxiv. Preprint server for health sciences. Aug 25,2021

 Link to Full Text: https://www.medrxiv.org/content/10.1101/2021.08.24.21262415v1.full-text