The Study: Impact of age, ethnicity, sex and prior infection status on immunogenicity following a single dose of the BNT162b2 mRNA COVID-19 vaccine: real-world evidence from healthcare workers, Israel, December 2020 to January 2021 

 Overview: The study looked at antibody levels in a group of health care workers previously infected with SARS- CoV-2.  Subjects subsequently received their first dose of the vaccine (Pfizer-BNT162b2 mRNA COVID19 vaccine) and were evaluated in terms of their antibody response.  

 Key Points: 

·         As of 1-25-21, Israel had vaccinated nearly 30 percent of its population with a single dose of vaccine ranking it as the highest proportion in the world. 

·         This study looked at 514 health care workers who received their first dose of the Pfizer vaccine AND had previously tested positive (PCR test) for SARS-CoV-2.  

·         385 of these subjects also had their IgG levels tested prior to vaccination.  

·         Subjects then had their antibody levels measured 21 days after vaccination. 

·         92% of subjects had detectable SARS-CoV-2 spike antibodies.  

·         Those subjects who did not respond to the vaccine dose tended to be older (median age 57 vs. 45 in the responder group). There was no difference between males and females but antibody titres definitely decreased with increasing age.  

·         Incidence of other co morbidities was not included in the study. 

·         Compared with HCWs with no evidence of previous infection, post-vaccination antibody levels were much higher among those with a previous history of infection. (Geometric Mean Concentration levels of 573 vs 61.5 in previously uninfected subjects.) 

·         The authors conclude that “vaccinating individuals with evidence of prior COVID-19 infection lead to a boost response, achieving IgG titres approximately one order of magnitude higher compared with naïve individuals. Interestingly, this was the case in our cohort regardless of whether SARS-CoV2 N antibodies were detectable or not immediately before vaccination and regardless of the time interval between infection and vaccination.” 

·         Although the authors acknowledge the relatively small number of subjects, they conclude their observations  “provide reassurance that the well documented rapid waning of nucleocapsid IgG antibodies post-acute COVID-19 infection does not necessarily translate to a loss of immunity.” 

Author’s Conclusions: “The boost-like response seen among previously infected individuals in our cohort suggests B-cell-mediated memory immunity is preserved regardless of IgG (antibody) status.”  Parenthesis ours. 

Reviewer's Comments: I suspect we’ve all seen any number of scary headlines suggesting because antibody levels tend to drop within a month or two following infection, that no one is going to have any lasting immunity. (Translation…we’re all doomed! ) This study leads us to a much more optimistic conclusion….prior infections do tend to bring some level of lasting immune response regardless of antibody levels. While it’s true that antibody levels do tend to drop, the beneficial effects of B-Cell response are much longer lasting. The same mechanisms which brought about such an elevated “booster” type response following a single vaccine dose in this study, are almost certainly in play should we be so unfortunate to become infected a second time. My conclusion…while COVID-19 remains a very real threat to certain subgroups, nature continues to work through the process.

 Reviewer:  Mark R. Payne DC

Reference:  Kamal Abu Jabal , Hila Ben-Amram , Karine Beiruti , Yunis Batheesh , Christian Sussan , Salman Zarka  and Michael Edelstein

Impact of age, ethnicity, sex and prior infection status on immunogenicity following a single dose of the BNT162b2 mRNA COVID-19 vaccine: real-world evidence from healthcare workers, Israel, December 2020 to January 2021. Eurosurveillance 26(6) 2100096 (11/02/2021)

 Link to Full Text: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.6.2100096