ABSTRACT
COVID-19 caused by SARS-CoV-2 can develop the disease with different degree of clinical severity including fatality. In addition to antibody responses the antigen specific T cells may play a critical role in defining this protective immune response against this virus. As a part of a longitudinal cohort study in Bangladesh to investigate B and T cell specific immune responses, we sought to evaluate the activation induced cell marker (AIM) and the status of different immune cell subsets during infection. A total of 115 participants were analyzed in this study which included participants with asymptomatic, mild, moderate and severe clinical symptoms. In addition, healthy controls (19 in each group) were analysed. Specimens from participants collected during the pre-pandemic period were also analyzed (n=10). Follow-up visits were conducted on day 7, 14, and 28 for all the cases since the enrollment (day 1). In this study 10 participants among the moderate and severe cases expired during the course of follow up. We observed a decrease in mucosa associated invariant T (MAIT) cell frequency on the initial days (day 1 and day 7) in comparison to later days of the COVID-19 infection. However, natural killer (NK) cells were found to be elevated in symptomatic patients just after the onset of disease compared to both asymptomatic patients and healthy individuals. Moreover, we found AIM+ (both OX40+ CD137+ and OX40+ CD40L+) CD4+ T cells to show significant increase in moderate and severe COVID-19 patients in response to SARS-CoV-2 peptides (specially spike peptide) compared to prepandemic controls, who are unexposed to SARS-CoV-2. Notably, we did not observe any significant difference in the CD8+ AIM markers (CD137+ CD69+), which indicates the exhaustion of CD8+ T cells during COVID-19 infection. These findings suggest that the patients who recovered from moderate and severe COVID-19 were able to mount a strong CD4+ T cell response against shared viral determinants that ultimately induced the T cells to mount further immune responses to SARS-CoV-2.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the safety of a group A + C meningococcal polysaccharide vaccine as part of a phase IV clinical trial.</p><p><b>METHODS</b>The study area was divided into 108 clusters according to the principle of cluster randomization, stratified and paired sampling methods. 54 out of 108 clusters served as observation groups were administered A + C vaccine, while the rest 54 groups were administered Vi polysaccharide vaccine. An adverse event surveillance system was established to monitor the adverse events following the vaccination campaign. Identical form and methods were used for data collection to investigate the adverse events following the vaccination of both A+ C vaccine and Vi vaccine.</p><p><b>RESULTS</b>34,543 people were vaccinated, including 18,167 of whom received A + C vaccine, while the other 16,376 received Vi vaccine. The rates of immediate injection reaction and unsolicited non-serious adverse events from A + C vaccine group were 0.44% and 0.38% while of Vi vaccine group were 0.79% and 0.73% respectively. At the solicited adverse event survey on 3-day-post-vaccination, 1239 vaccinees were followed-up including 771 received A + C vaccine and 468 received Vi vaccine. The local injection reaction rate of A + C vaccine group on the 1st day was significantly higher (X2 = 13.98, P = 0.0002) than that of Vi vaccine group. Neither the local injection reaction rate nor the system reaction rate between both groups was significantly different on 2nd and 3rd day, post vaccination. It was not statistically different when comparing fever onset rate between those who received vaccine and those who did not, in each vaccine group. There were no serious adverse events observed.</p><p><b>CONCLUSION</b>Results showed that the side effects of A + C vaccine and the Vi vaccine were mild and safe for vaccination campaigns targeting on populations at different age.</p>
