Background: Although changes of the main lymphocyte subsets (T cells, T helper, T cytotoxic, B cells, NK cells) and lymhocyte activation status in COVID-19 patients have been reported, the results of the studies differ each other. Therefore, we aimed to determine lymphocyte subgroups and activation status of them with flow cytometry at the time of diagnosis in COVID-19 patients and examine the relation of them with disease stage and length of hospital stay. Methods: Fourty patients included in the study were compared with the age and sex matched 40 healthy controls. COVID-19 patients were divided into 2 groups as mild and severe stage disease. Flow cytometry assay was performed to examine the numbers of lymphocyte subsets and activation status of them. Total lymphocyte count was calculated and CD45, CD3, CD4, CD8, CD19, CD27, CD38, CD56, CD57, IgD were studied on lymphocyte gate. T helper / T cytotoxic rates and length of hospital stay were recorded. Results: The patients’ CD3(+)CD4(+) ( T helper) count and CD27 expression on T cells counts were significantly lower, and CD57 expression on CD3(+)CD8(+) T cytotoxic cells were significantly higher (p<0.05) than control gruop. When the patients were divided into mild and severe stages, it was observed that CD38 expression on T cells were significantly lower in severe stage patients (p< 0.05) Total lymphocyte count and CD3(+) T lymphocyte count were negatively correlated with the lengt of hospital stay as statistically significant (p <0.05). Conclusion: Our data showed that the SARS-CoV-2 primarly effects on T lymphocytes. It was thought that this effect occured by impairment of development and activation of T lymphocytes. There are some discordances among the studies on T lympocytes in the literature. Studies with more patients are needed to make this information more reliable.

Objectives: Studies have shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is primarily transmitted from person to person via airborne droplets. It is unclear whether it can be shed into human milk and transmitted to a child via breastfeeding.We investigated the presence of SARS-CoV-2 RNA in human milk samples of 15 mothers with coronavirus disease 19(COVID-19) and in the throat swab samples of their infants. Methods: This is a prospective observational study in which breast milk samples were collected from 15 mothers with COVID-19. The presence of SARS-CoV-2 RNA in the whole human milk samples of the patients was investigated using RT-qPCR. All of the infants underwent a clinical follow-up during their 14-day isolation and their throat swab samples were tested for SARS-CoV-2 RNA. Results: Of 15 mothers with COVID-19, SARS-CoV-2 RNA was detected in milk samples from 4 mothers. The throat swab samples from these mothers’ infants were found to be positive for SARS-CoV-2 RNA. Three of the four mothers were breastfeeding. In addition, during the 14-day isolation, all but three of the mothers breastfed their infants. Of the 12 breastfed infants, while the test for SARS-CoV-2 RNA in throat swab samples was negative in six of the infants, the other six infants, who had mild COVID-19 symptoms, tested positive for SARS-CoV-2 RNA.Clinical outcomes of all mothers and infants were uneventful. Conclusion: To our knowledge, this is the first case series with the largest number of cases with SARS-CoV-2 RNA positivity in human milk samples of mothers with COVID-19. However, we believe that the benefits of breastfeeding may outweigh the risk of SARS-CoV-2 infection in infants