In a recent study published in medRxiv* Prepress server, researchers investigated the effect of binding antibodies on severe acute respiratory infections with Omicron coronavirus 2 (SARS-CoV-2).
Coronavirus disease 2019 (COVID-19) vaccines have played an important role in protecting against and severe SARS-CoV-2 infection. However, there is insufficient knowledge regarding the protection elicited by antibodies against emerging variants of SARS-CoV-2.
In this study, the researchers investigated antibody binding titers and the interaction between the viral receptor-binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2) in SARS-CoV-2 omicron penetrating infection.
The study included 12 participants who were enrolled in an ongoing, longitudinal community study of SARS-CoV-2 (CITY). Participants answered a questionnaire regarding their demographic information and medical history. The team obtained nasal swabs from individuals to detect SASR-CoV-2 infection, while whole blood samples were collected for serological testing. Eligible participants reported a penetrating infection between December 15, 2021 and January 7, 2022. Participants also provided information regarding symptoms associated with the penetrating infection.
The team confirmed the presence of superinfections with a positive nucleic acid amplification test (NAAT) such as polymerase chain reaction (PCR). The enzyme-linked immunosorbent assay (ELISA) was subsequently performed using a two-step method developed at Mount Sinai. An antibody-binding titer assay was also performed to detect immunoglobulin G (IgG) via the VITROS assay. Furthermore, the team performed a semi-quantitative alternative testing of SARS-CoV-2 (SNA) that evaluated the inhibitory capacity of RBD-ACE2 interactions.
In the group of eligible participants, the mean age was 50.5 years, and nearly 50% of the group was female. The group also included 83.3% of whites and 66.6% of Hispanics. Nearly 50% of all participants reported a previous infection with COVID-19.
All study participants received the initial vaccine series more than 90 days prior to breakthrough infection. Of the vaccinated individuals, 66.7% received the Pfizer/BNT162b2 vaccine, 25% received the Moderna messenger (mRNA)-1273 ribonucleic acid vaccine, and 8.3% received the Johnson & Johnson Ad26.COV2.S vaccine. Only two participants who did not receive a booster dose reported a history of SARS-CoV-2 infection. Notably, one individual vaccinated with the Ad26.COV2.S vaccine was infected twice before receiving the vaccine. Among the boosted individuals, 28.6% received the BNT162b2 vaccine, while 71.4% received the mRNA-1273 vaccine.
The team classified all penetrating injuries as mild and with no medical intervention or hospitalization. Furthermore, among the participants who experienced a breakthrough infection, 66% reported a cough, 66.6% had a congestion or runny nose, 41.6% had a sore throat, and 41.6% had a headache. Furthermore, all participants showed detectable amounts of antibodies against SARS-CoV-2 with titers ranging from 1:800 to 1:51,200 by the Mt assay. Sinai and 57.4 to 13,500 BAU/ml with the VITROS test. An inhibition assay performed to test for RBD-ACE2 interaction also showed that 83.3% of participants had detectable alternative neutralization activity while 16.7% did not.
Furthermore, the team ranked the participants according to the number of SARS-CoV-2 antigen challenges, thus assessing vaccination-induced or natural immunity. Individuals who encountered only two SARS-CoV-2 antigen challenges had lower antibody titers. Furthermore, the booster participants showed higher antibody titers compared to those who did not receive their booster dose, except for those who received their second dose within 90 days of the penetrating infection.
The results of the study showed that the specific role and characteristics of the humoral response during infection and vaccination need to be clarified. According to the researchers, future studies should include profiles of cellular immunity to better define the immune landscape during the spread of infection.
medRxiv publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, guide clinical practice/health-related behavior, or be treated as established information.