CD4+ is associated with COVID-19-infected pneumonia patient recovery and recurrence

Coronavirus Disease 2019 (COVID-19)–infected pneumonia (CDIP) occurred in Wuhan, China, in December 2019, from where the disease has spread all over the world. Although the morbidity and mortality in China have been effectively controlled, the number of cases has increased rapidly in countries other than China. Here we report the epidemiological and clinical characteristics of 7 CDIP patients. We found that similar with the throat swabs, sputum induction still has a false negative rate. In addition, CD4+ count rise occurred before the disease remission, and decreased CD4+ count may be the cause of virus recurrence. These imply that CD4+ count could be a marker for recover and reinfection. Notably, we tentatively speculate that CD4+ plays a key role in the body's resistance to the COVID-19 attack on lung tissue.


Background
About December 2019, a cluster of acute viral respiratory disease, which is now known as Coronavirus Disease 2019 (COVID-19)-infected pneumonia (CDIP), appeared in Wuhan, Hubei Province, China [1,2], from where the disease has spread all over the world [2]. As of March 14, 2020, a total of 81029 CDIP cases in China have been con rmed, and 3914 NCIP dead. Internationally, a total of 62422 CDIP cases in countries other than China have been con rmed and 2226 CDIP dead in more than 136 countries and regions. It was reported that COVID-19 could be classi ed in the betacoronavirus 2b lineage because of its common characteristics with the coronavirus family. COVID-19 seemingly roots in bat [3], however, the exact origin of COVID-19 remains to be identi ed. The available evidence suggests that COVID-19 could infect human via human-to-human transmission [4]. Therefore, it is urgent to understand and identi y the processes for prevention and control, in order to prevent contamination in the world.

Study Design and Participants
All consecutive patients with con rmed CDIP were admitted to A liated Hospital of Guangdong Medical University from January to February, 2020. The clinical outcomes (i.e. epidemiological and clinical characteristics) were monitored up to March, 8, 2020, the nal date of follow-up.

Data Collection
The medical records of patients were analyzed by the research team of the A liated Hospital of Guangdong Medical University. Epidemiological, demographic, clinical, laboratory medicine, radiology, and treatment data were obtained from electronic medical records. The data were carefully reviewed by a group of highly trained doctors. Information recorded included demographic data, medical history, exposure history, background of disease, symptoms, signs, laboratory ndings, computed tomographic (CT) scans, and treatment measures (i.e. antiviral therapy and immunity enhancement therapy). The disease onset date was deemed as the day when the symptom was detected. Symptoms, laboratory test results, CT scans, disease progression, and treatment measures during the hospital stay were collected.

Results
Epidemiological data showed that all CDIP cases have direct or indirect contact with Wuhan residents.
The relationships between patients were determined. We found that Case1/Case2 and Case3/Case4 were couples, and COVID-19 could infect human via human-to-human transmission. The infection symptoms of CDIP suffering the background diseases were more pronounced than that of CDIP with no background diseases. The time of Case 6 onset is the same as the time of contact with Wuhan residents. At the diagnosis, CT scans data of all CDIP cases shows that the typical glass opacity lesion caused by COVID-19 mainly occured in both lungs lower parts (Table1). The period between nucleic acid test (Throat swabs) became negative and lung lesion reabsorption initiation was about 6-8 day. During the follow-up after discharge, at March 5, 2020, nucleic acid test (Throat swabs) of Case5 was positive (Table2).
Combining CT results with CD4 + count data, we found that CD4 + count rise occurred before the disease remission, and CD4 + count was consistent with disease progression (Table 3 and Figure1). 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 (Table 3).

Discussion
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 [4]. 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 [5], 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][7][8], nally, the virus persists in the body but has no symptoms same with HBV and HIV; Similar 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 identi cation; Not 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 signi cant marker of CDIP diagnosis [9]. 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 [10], and its count in uences immunological recovery of HIV infection [11], 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 con rmed in Case 5. CDIP patients should be treated with immune-enhancing drugs such asγ-globulin and Thymosin used in Case1 and Case5 treatment.

Conclusions
The epidemiological, clinical characteristics and treatment of CDIP were summarized and analyzed. CD4 + count may be a marker for recover and reinfection. We preliminarily could speculate that CD4+ plays a key role in the body's resistance to the COVID-19 attack on lung tissue and boosting immunity is useful to Ethics Approval and Consent to Participate: The study protocol, any amendments, the informed consent, and other information that required pre-approval were reviewed and approved by a national, regional, or investigational site ethics committee or institutional review board (IRB), in accordance with the International Council for Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use Good Clinical Practice and applicable country-speci c requirements. All study patients provided written informed consent.  Lung CT scans of case 1-7