June 22, 2024

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COVID-19 patients without infectiousness even IgM positive over 1 year

COVID-19 patients without infectiousness even IgM positive over 1 year


COVID-19 patients without infectiousness even IgM positive over 1 year.  Two COVID-19 patients rule out the possibility of two people’s infectiousness even IgM positive more than 1 year. 


China CDC Weekly) recently published a study that reported two cases of persistently positive cases of COVID-19 IgM antibodies. Two patients had a negative nucleic acid test, and there was no possibility of recurrence or re-infection with the new coronavirus, but the IgM antibody test results of both patients continued to be positive for 8 months (the study deadline is February 2021).

According to the study, the persistent IgM positive in the two infected persons may be related to suppressive and/or dysregulated immune system activity; the persistent lgM positive in the two cases indicates the possibility of long-term and intermittent virus shedding. Virus shedding means that people can excrete or release the virus after a virus infection.

Zhao Bennan, the first author of the study and attending physician at Chengdu Public Health Clinical Medical Center, said in an interview with The Paper (www.thepaper.cn) that the two cases have recovered well and have completely returned to normal life.

Their IgM antibody titers decreased during the examination last week. Zhao Bennan believes that the IgM of the two cases may gradually decline, but long-term observation is needed when it turns negative. This also means that the duration of IgM antibodies in 2 cases exceeded one year.

Zhao Bennan said that continued positive IgM is not related to a positive nucleic acid test. Current tests and observations show that the two cases are not contagious. “After discovering these two patients, we followed them up closely, conducted regular nucleic acid tests, and even contacted the CDC to isolate them for a short period of time. During the period, they were repeatedly sent for throat swabs and secretions. The nucleic acid test of the specimens was negative, and the nucleic acid test results of the family and living environment were also negative, which ruled out the two people’s concern about being infectious.” Zhao Bennan said.

In the “COVID-19 Pneumonia Diagnosis and Treatment Plan (Trial Eighth Edition)” issued by China National Health Commission, the new coronavirus diagnosis standard adds antibody testing to the original nucleic acid test. Infection with the new coronavirus can cause the body’s adaptive humoral immune response. By detecting the specific IgM and IgG in the blood of the infected person, it can be indirectly judged whether the body is carrying the virus. Among them, IgM is generally produced in the initial stage of infection, indicating recent infection; IgG is an antibody produced after the pathogen stimulates the secondary response of effector cells, which may indicate that the infection has entered the recovery period or has recovered.

Previous studies have shown that immunoglobulin M (Immunoglobulin M, IgM) usually appears in the early stage and lasts for a short time, so it is usually used as an indicator to diagnose whether it is infected with the virus. A three-month study of healthcare workers infected with COVID-19 in a Spanish hospital estimated that the duration of IgM in patients with COVID-19 was 1.95 months; based on the study of 69 COVID-19-specific IgM positive patients in Wuhan from April to December 2020. , IgM can last for 9 months.

A follow-up study in Guangzhou published in “Nature” in late August showed that the COVID-19-specific IgM can drop to the background level within 1 year (as shown below). The IgM level dropped sharply from 4.669 to 0.785 (negative) 3 months after discharge, which was 6 times that of the former.


COVID-19 patients without infectiousness even IgM positive over 1 year

Of the 34 patients who were followed up for one year in the study, only patients A and B were consistently positive for lgM. Both patients A and B met the discharge criteria, but the nucleic acid test results were positive again at the first follow-up, and their COVID-19-specific lgM test results continued to be positive for more than 8 months.

The researchers mentioned that, in general, persistent lgM positive results are related to reinfection or recurrence. Since the two cases did not have close contact with other patients infected with COVID-19 during their hospitalization and recovery, the possibility of re-infection is very small. In addition, patients A and B did not relapse after the second follow-up. Therefore, the researchers believe that the continuous positive lgM of the two patients means that the virus in the two patients has not been completely eliminated, and it is possible that the virus replication is maintained at a low level, so the amount of virus is below the detection limit.

Patient A is a 41-year-old male. After returning to Chengdu from Wuhan on January 22, 2020, he developed fever with a temperature of 38°C. He was diagnosed as positive for COVID-19 by the Chengdu CDC and was admitted to the Chengdu Public Health Clinical Center on January 26, 2020. Chest CT examination showed that patient A had multiple plaque-like ground glass shadows in the upper, middle, and lower lobes of the right lung, and the upper and lower lobes of the left lung, as well as pericardial effusion.

Patient B is a 45-year-old female. After returning to Chengdu from Japan on January 23, 2020, he suffered from shortness of breath, muscle aches, and decreased muscle strength. Five days later, he developed fever with a maximum temperature of 38.3°C and was subsequently sent to Sichuan Provincial People’s Hospital for treatment. On January 29, 2020, he was tested positive for COVID-19 by the Chengdu Center for Disease Control and Prevention. Chest CT examination showed multi-lobed multi-nodular plaques, ground-glass density shadows, and nodular shadows, especially in the upper lobes of the lungs. About half a month later, another chest CT examination showed a small amount of pericardial effusion.

According to the “Diagnosis and Treatment Plan for COVID-19 (Trial Fifth Edition)”, patients A and B are classified as ordinary cases of COVID-19 (Editor’s note: with fever, respiratory symptoms and other symptoms, imaging can show pneumonia manifestations). As of February 9, 2021, patient A and patient B have been followed up 7 times in one year (as shown in the figure below).

In the first follow-up about half a month after discharge, the two patients both showed positive nucleic acid test results and were re-admitted to the hospital immediately. After the second discharge, the two patients continued to participate in regular follow-ups, and their nucleic acid tests were negative.

However, from the fourth follow-up (about four months after the onset) to the latest follow-up (about one year after the onset), their new coronavirus-specific IgM antibody test results have remained positive.


COVID-19 patients without infectiousness even IgM positive over 1 year


Zhao Bennan predicted that the specific IgM of the two cases should gradually decline, but it is impossible to determine when they will turn negative. “So we also conducted close follow-up observations on these two cases, and asked them to come over for nucleic acid collection and antibody testing every two months.”

Zhao Bennan emphasized, “Every person’s situation is different, and the changing trends in the body are also different. Two points need to be clarified. First, whether it is infectious or not, and second, whether it affects the patient’s body.” Zhao Bennan said that both patients have Return to normal life.

In the study, it is inferred that the reason why patients A and B have continuous positive lgM for COVID-19 may be related to their inhibitory and/or dysregulated immune system activities. Immune system activity may take longer to completely remove the virus, and the remaining virus can stimulate the body to produce antibodies, resulting in continued positive IgM-specific IgM. Previous studies have shown that reduction in IgM may be an indicator of virus clearance.

However, Zhao Bennan also said that the reason for the continued positive IgM made here is only an inference, and further research is needed. “Now we see a problem, that is, the number of persistent positive IgM cases is really too few. We wrote this report mainly to raise this issue, and we also hope to attract the attention of other clinical academic workers. It is best for everyone to take this kind of Cases can be assembled and matched for case-control studies.” Zhao Bennan said.



(source:internet, reference only)

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