Abstract
Thailand is another country affected by the coronavirus disease 2019 (COVID-19) pandemic, which has affected the public health system and its economy. Therefore, it is important to develop cognition in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as quickly as possible. Therefore, this research aims to study the kinetics of immune response patterns after SARS-CoV-2 infection both mild and severe symptoms. The information on a kinetic immune response from SARS-CoV-2 infection can help to predict prolonged immunity. Understanding antibody responses after natural SARS-CoV-2 infection can guide the COVID-19 vaccine boosting schedule in this population. The objective of this study to assess the dynamics of SARS-CoV-2 antibodies, including anti-nucleocapsid protein (N), immunoglobulin (Ig)G, anti-spike protein 1 (S1) IgG, anti-receptor-binding domain (RBD) total Ig, anti-S1 IgA, and neutralizing antibody against wild-type SARS-CoV-2 in a cohort of patients who were previously infected with SARS-CoV-2. The research method starts with RT-PCR screening to confirm the results of SARS-CoV-2 infection and performs blood collection for immunogenicity testing at 3, 6, 9, and 12 months after the date of infection or confirm the results of infection to monitor immune levels by anti-nucleocapsid protein (N), immunoglobulin (Ig)G, anti-spike protein 1 (S1) IgG, anti-receptor-binding domain (RBD) total Ig, anti-S1 IgA, and neutralizing antibody ต่อ SARS-CoV-2 against wild type. The population studied and followed during the periods was as follows: 531 volunteers in the project were divided into 420 SARS-CoV-2 infected with mild symptoms and 111 SARS-CoV-2 infected with severe symptoms, divided into 269 males, and 262 females The average age is 38. The total specimens enrolled in this study are 968 samples, divided throughout sample collection. The following: 376 samples of 3-month periods after infection, 241 samples 6-month periods after infection, 207 samples 9-month periods after infection, and 144 samples 12-month periods after infection. The results showed that seropositivity rates began to decrease during the period 6 months after infection and started to decline continuously after symptom onset 6–12 months. The seropositivity rate was significantly lower at 6, 9, and 12 months than at 3 months (p-value < 0.05), especially in SARS-CoV-2 infected with pneumonia symptoms was showed higher seropositivity rate than in SARS-CoV-2 infected with non-pneumonia/asymptomatic group at 6 months (p-value < 0.05), 9 months (p-value = 0.04), and 12 months (p-value = 0.04). At 6, 9, and 12 months after infection, the anti-N IgG levels were significantly reduced. The seropositivity rates of anti-N IgG reduced by less than 50% 6 months after infection, while seropositivity rates of anti-RBD total Ig, anti-S IgG, and anti-S IgA still had more than 80% seropositivity rate. The immunogenicity levels among SARS-CoV-2 infected with severe symptoms were significantly higher than SARS-CoV-2 infected with mild/asymptomatic. At 12 months, the seropositivity rate among SARS-CoV-2 infected with mild/asymptomatic individuals in each method of examination found seropositivity rates as follows: anti-N IgG 21.5%, anti-RBD total Ig 87.0%, anti-S IgG 59.3%, and anti-S IgA 74.1%. The seropositivity rate in the SARS-CoV-2 infected with severe symptoms was found as follows: anti-N IgG 41.7%, anti-RBD total Ig 97.2%, anti-S IgG 91.7%, and anti-S IgA 86.1%. In some cases, the immunogenicity can be found prolonged for more than 12 months. Moreover, we found no significant difference between immunogenicity response and sex. In Elder (>60 years), the immunogenicity response showed significantly lower than in adults (≤ 60 years). These data on the natural history of SARS-CoV-2 antibodies will be useful for comparing and planning the future COVID-19 vaccination. Normally, SARS-CoV-2 antibodies in infected patients can be prolonged for more than 6 months and these patients may not be necessary to receive the COVID-19 vaccine within 6 months after clearance.
