Comparable humoral and cellular immunity against Omicron variant BA.4/5 of once‐boosted BA.1/2 convalescents and twice‐boosted COVID‐19‐naïve individuals

Abstract

The fourth vaccination dose confers additional protective immunity against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection in individuals with no prior coronavirus disease‐19 (COVID‐19). However, its immunological benefit against currently circulating BA.4/5 is unclear in individuals who have received a booster shot and been infected with Omicron variant BA.1/2. We analyzed immune responses in whom had been boosted once and did not have COVID‐19 (n = 16), boosted once and had COVID‐19 when BA.1/2 was dominant in Korea (Hybrid‐6M group, n = 27), and boosted twice and did not have COVID‐19 (Vx4 group, n = 15). Antibody binding activities against RBDo BA.1 and RBDo BA.4/5, antigen‐specific memory CD4+ and CD8+ T‐cell responses against BA.4/5, and B‐cell responses against SARS‐CoV‐2 wild‐type did not differ statistically between the Hybrid‐6M and Vx4 groups. The humoral and cellular immune responses of the Hybrid‐6M group against BA.4/5 were comparable to those of the Vx4 group. Individuals who had been boosted and had an Omicron infection in early 2022 may not have high priority for an additional vaccination.

Humoral and cell-mediated immune responses in HIV-vertically infected young patients after three doses of the BNT162b2 mRNA SARS-CoV-2 vaccine

“…Data herein indicate that three doses of the BNT162b2 mRNA vaccine are able to elicit robust humoral and cell-mediated immune responses in ART-treated, HIV-vertically-infected young patients. Our results also confirm that SARS-CoV-2 infection before vaccination, resulting in the so-called hybrid immunity, is associated with the development of stronger immune responses compared to vaccination alone, as previously reported in the general population (30,31). Two important and novel results emerging from our analyses are: 1) while vaccine-induced humoral immune responses are comparable in PLWH and HC, cell-mediated immunity is qualitatively different and, possibly weaker in PLWH; and 2) while vaccination does not reactivate viral replication, it can result in a non-marginal reduction of CD4+ T lymphocytes in a minority of PLWH.…”

A recombinant spike‐XBB.1.5 protein vaccine induces broad‐spectrum immune responses against XBB.1.5‐included Omicron variants of SARS‐CoV‐2

“… 30 Both antigen‐specific CD4 + and CD8 + T‐cell immune responses have been detected after SARS‐CoV‐2 infection or vaccination, which is closely related to the activation of humoral immunity. 31 Hence, we next evaluated the capacities of the six vaccines in activating cellular immune responses. Two weeks after the third vaccination, splenic lymphocytes of the immunized mice were isolated and restimulated ex vivo with RBD‐XBB.1.5 or RBD‐BA.5 antigens for 48 h. T‐cell responses were then determined with flow cytometry and intracellular cytokine staining.…”

“…The establishment of helper T‐cell (CD4 + ) responses is required for the formation of strong antibody responses as well as cytotoxic CD8 + T‐cell responses 30 . Both antigen‐specific CD4 + and CD8 + T‐cell immune responses have been detected after SARS‐CoV‐2 infection or vaccination, which is closely related to the activation of humoral immunity 31 . Hence, we next evaluated the capacities of the six vaccines in activating cellular immune responses.…”