By Neha MathurJan 18 2023Reviewed by Danielle Ellis, B.Sc. In a recent article published in Scientific Reports, researchers performed an observational study among coronavirus disease 2019 patients and their close contacts registered with the Bangkok home health care services in Thailand. They assessed their T-cell and neutralizing antibody responses six months after exposure to severe acute respiratory syndrome coronavirus 2 .
Moreover, close contacts of infected cases developed T-cell immunity against SARS-CoV-2, which kept COVID-19-related death rates in Bangkok low, even among cases treated at home care centers. However, reluctance to receive the vaccine and the advent of new immune-evading SARS-CoV-2 variants hindered meeting the herd immunity threshold.
Study findings During SARS-CoV-2 exposure, COVID-19 patients and their close contact in each family coinhabited the same healthcare home, with an area of approximately 200 m2. The study population comprised 15 families with 11 members in each family, and 58% were females. Over 90% of members were under 60, and 81% had a body mass index of less than 30. In addition, one-fifth of the study participants, 26.5% of the patients and 15.
Conversely, the researchers noted a decrease in T-cell responses against the S antigen increased as vaccine doses, i.e., with the third or fourth booster. Thankfully, studies have demonstrated T-cell responses against the SARS-CoV-2 Omicron variant rapidly reactivated three months after boosting. Vaccine type might have confounded these responses.