Case1/Case2 and Case3/Case3 are couples, which is consistent with the report that a familial cluster of pneumonia associated with the COVID-19 showed person-to-person transmission. Moreover, we found that the period between negative nucleic acid test (Throat swabs) and lung lesion reabsorption initiation is about 6-8 day. In addition to age, disease progression may also be related to the body's health. The infection symptoms of CDIP suffering the background diseases are more pronounced than that of CDIP with no background diseases, which is likely to affect the CDIP patient survival. The time of Case 6 onset is the same as the time of contact with Wuhan residents, although this patient is young and has no background disease. Epidemiological data showed that compared with others, Case 6 contacted and dined with a large number of Wuhan residents in Zhanjiang at on one day. Hence, exposure to large amounts of the virus may be the inducer of onset acceleration.
According to our previous results, in order to improve the positive rate of diagnosis and make a basic guarantee for the improvement of defense and prevention and control, the method of inducing sputum could be used to detect nucleic acid for high-risk population exposed to epidemic area. It was found during follow-up that Case 5, as Case 2 was reported at Lancet Infect Dis March 12, 2020 nucleic acid test (Throat swabs) is positive at March 5, 2020 but has no symptoms, however, the paper shows both nucleic acid test (induced sputum) and nucleic acid test (Throat swabs) of Case 2 were negative. There may be 3 reasons that could result in the CDIP reinfection: After a series of treatments, the proliferation of COVID-19 is effectively controlled, showing low load or dormant, even lurking in other organs, such as the intestinal, circulatory systems and urinary system[6-8], finally, the virus persists in the body but has no symptoms same with HBV and HIV;②Similar with the throat swabs, sputum induction still has a false negative rate. CT scans show that glass opacity lesion mainly located in lungs lower parts, as far as possible, sputum in the base of the lungs should be collected for identification; ③Not only CD4+ count of Case 2 is lower than that of other cases, but also lower than normal level.
We found that CD4 count is consistent with disease progression: in case1 and Case 7, CD4+ count rised from 380 and 285 to the normal, respectively; as deterioration occured in Case 2, CD4+ count was decreased from 546 to 250; when Case 5 was discharged from the hospital, the CD4+ count was below normal. We also found that LY(%) data is almost normal in Case 1，Case 2 and Case 3; Moreover, when CD4+ count is lower than normal, LY(%) is still almost normal in Case 1，Case 2 and Case 3. However, previous studies have shown that peripheral lymphocytes decrease is one significant marker of CDIP diagnosis. Above all, CD4+ may be more sensitive to COVID-19 infections than that of LY(%).It was reported that CD4+ is mainly expressed in T cells, and its count influences immunological recovery of HIV infection, HIV therapeutic methods may be used to treat the COVID-19 infection. We further compared the change time of CT scan and CD4+ count, and found that CD4+ count rise occurred before the disease remission, which means that CD4+ count rise may be a marker for recover, Therefore, when CD4+ count is lower than normal, it may be the cause of virus recurrence, which may be confirmed in Case 5. CDIP patients should be treated with immune-enhancing drugs such asγ-globulin and Thymosin used in Case1 and Case5 treatment.