The impact of prior COVID-19 on vaccine response and the resultant hybrid immunity are age-dependent

Abstract

Background More people with a history of prior infection are receiving SARS-CoV-2 vaccines. Understanding the magnitude of protectivity granted by hybrid immunity, the combined response of infection- and vaccine-induced immunity, may impact vaccination strategies. Methods A total of 36 synchronously infected (prior infection) and, 33 SARS-CoV-2 naive (naive) individuals participated. Participants provided sera six months after completing a round of BNT162b2 vaccination, to be processed for anti-spike antibody measurements and neutralization assays. The relationships between antibody titer, groups and age were explored. Results Anti-spike antibody titers at 6 months post-vaccination were significantly higher, reaching 13- to 17-fold, in the prior infection group. Linear regression models showed that the enhancement in antibody titer attributable to positive infection history increased from 8.9- to 9.4- fold at age 30 to 19- to 32-fold at age 60. Sera from the prior infection group showed higher neutralizing capacity against all six analyzed strains, including the Omicron variant. Conclusions Prior COVID-19 led to establishing enhanced humoral immunity at 6 months after vaccination. Antibody fold-difference attributed to positive COVID-19 history increased with age, possibly because older individuals are prone to symptomatic infection accompanied by potentiated immune responses. Durable protection of hybrid immunity deserves reflection in vaccination campaigns.

Antibody Avidity Maturation Following Recovery From Infection or the Booster Vaccination Grants Breadth of SARS-CoV-2 Neutralizing Capacity

“…In the present study, we correlated the kinetics of serum antibody avidity maturation, which followed SARS-CoV-2 natural infections, as well as vaccine administrations, to the magnitude and breadth of in vitro neutralizing capacity. The immune status in individuals who have experienced COVID-19 before or after their receipt of a SARS-CoV-2 vaccine is often referred to as “hybrid immunity” [ 9 ], and is known to confer enhanced protection against variable SARS-CoV-2 strains [ 10 ]. Our observations provide a logical perspective on the variable durability and resilience of the 2 building blocks, the natural infection immunity and the vaccine-elicited immune response, needed for the acquisition of hybrid immunity.…”