Since the outbreak of the new crown outbreak, we have gained a lot of knowledge about the new coronavirus and the COVID-19 disease it causes. So far, however, there are still many COVID-19-related puzzles that have not been solved. One of the most important questions is how immune to the new coronavirus is. The body’s immune response to the new coronavirus is the key to protecting people from the new coronavirus in the future, and is the basis for the development of all new coronaviruses, so can the immune response of the human body from the new coronavirus protect us from the new coronavirus? How long can this protective effect last?
A joint research team published a joint research team in The Lancet’s Journal of The Lancet. The researchers followed 651 patients with new coronary pneumonia who were discharged from Wuhan Lung Hospital between January 11 and April 1 this year. They found that 23 (3%) of those who met the discharge criteria and were confirmed negative after two nucleic acid tests turned out again during the follow-up. So what is the reason why these patients’ nucleic acid test results are “yin-to-yang”? Do the antibodies in their bodies protect them? Let’s take a look at the detailed results given by the researchers.
“Yin-yang” patient profile
The median age of 23 nucleic acid tests for “yin and yang” was 56 years (27.0-89.0 years), including 12 women and 11 men. When these patients were last admitted to hospital with COVID-19, 12 (52%) were moderate, 9 (39%) were serious patients and 2 (9%) were critically ill. The median time from discharge to nucleic acid testing again is 15.0 days (4-38 days).
Timeline of nucleic acid testing and re-yang in discharged patients
Antibody levels in patients, SYMPTOMS OF COVID-19 and clinical consequences
During nucleic acid testing, the patient was also tested for serological testing of antibodies to the new coronavirus. This serological test is based on the immunotomized paper test of colloidal gold. The results showed that both IgG and IgM antibodies were positive in 7 (30%) patients, 5 (22%) positive for IgG antibodies, and IgM tested negative. The remaining 11 (48%) patients tested negative for both antibodies.
In this group of patients, 15 (65%) had no symptoms when retested, while 8 (35%) showed at least one symptom associated with active COVID-19, specifically 6 patients with fever, 2 with cough, 1 patient reported fatigue, 1 patient had difficulty breathing, and 1 patient had chest urgency (chest tightness).
At the last follow-up on 4 April, all 23 “yin and yang” patients were still alive, 18 (78 per cent) had recovered and been discharged again, 4 were still hospitalized for medical care and one was self-isolated at home.
The reasons for the re-emergence of nucleic acid testing in rehabilitative patients have not yet been fully clarified, the researchers said in their comments. Although nucleic acid testpositive results in asymptomatic rehabilitation patients may be associated with residual non-pathogenic viral components, positive results in patients who show symptoms mean that the disease is likely to recur.
Given that 52% of patients in this patient group carry antiviral IgG antibodies, 30% of patients carry IgM antibodies, which means that their immune systems partially immune to the new coronavirus. However, the effectiveness of antiviral antibodies in removing COVID-19 remains a question to be answered because 35% of patients develop one or more COVID-19-related symptoms. Whether a patient can continue to spread the virus after discharge from the hospital is worth further study. To prevent a second wave of COVID-19 infection, the researchers recommend that patients with COVID-19 rehabilitation undergo clinical observation for at least 14 days after discharge from the hospital.