How big is the long-term impact of COVID-19 infection

People are tested for COVID-19 in Seoul, South Korea, on Feb. 10. (Xinhua News Agency/Reuters/Photo)

Avoiding severe illness and death may not be the whole problem for people living with COVID-19. For some people, even after the virus is cleared, there may still be some persistent conditions, which are called the sequelae of the new crown or long-term new crown pneumonia. Scientists noticed the problem not long after the pandemic began and were concerned about its severity.

Since the global spread of the Omiljunn variant in December 2021, the number of people confirmed to be infected with COVID-19 around the world has exceeded 350 million by January 2022, and considering that the proportion of mild and asymptomatic Omilon caused by It is likely to be higher, coupled with differences in testing policies and capabilities across regions, the number of people who have actually been infected with COVID-19 is likely to be higher. As more and more people experience COVID-19 infection, the importance of this issue is also highlighted by how much the subsequent impact of infection on personal health is.

Recently, a laboratory study of people infected with the new crown virus found that some people may continue to have a relatively high inflammatory response in the body eight months after infection with the new crown. This provides new evidence for understanding the long-term health effects such as the aftermath of COVID-19.

Natural immune cells are highly active

Researchers from the University of New South Wales in Australia compared the differences in immune systems between those with COVID-19 sequelae and those who were infected but did not have sequelae, and found that those who still had the condition after three or four months of infection were highly active and showed a sustained immune response. Compared with people infected with other coronaviruses and healthy people, the immune status in patients with COVID-19 sequelae is also unique. More critically, the immune system characteristics of patients with covid-19 sequelae are not because of the severity of the previous infection, but rather, the infected people included in the analysis have only mild and moderate symptoms. The study was published in Nature Immunology in January 2022.

Cases with long-term SEQUEL are those who still have one or more symptoms four months after infection, such as dyspnea, fatigue, chest pain, etc. The latest study included a total of 62 people infected with COVID-19, half of whom had sequelae. The researchers collected serum samples for laboratory analysis about three, four, and eight months after their infection. The results show that the difference between the two types of infected people is continuous and significant, the immune system was originally active in response to the attack of the virus, for people with new crown sequelae, when the virus in their body has been cleared, the immune system is still active, these continuously found abnormal immune indicators, in fact, provide some physiological evidence for the existence of new crown sequelae.

While the mechanism behind this remains unclear, the researchers estimate that it may be because the antigen persists after the virus is cleared, or it may be because of autoimmunity, which causes the immune system to attack its own tissues instead, or it is a manifestation of the damage repair process. Longer laboratory studies are needed in the future to observe changes in these immune responses and to explore the mechanisms in greater depth. In addition, other physiological evidence is needed to prove and explain the phenomenon of covid-19 sequelae. You know, before that, the types of COVID-19 sequelae that have been found in clinical cases are not one or two, but at least 50.

The variety of sequelae has been increasing

As early as the beginning of 2020, when the new crown epidemic began, researchers at Wuhan Jinyintan Hospital began to track the health of discharged infected people, at that time, there was neither a widely available approved vaccine nor a lack of specific drugs. After an ongoing analysis of the physical condition of nearly 2,000 infected people who were discharged from hospital from January to May 2020, the researchers found that 76 percent of those infected still had at least one symptom at the age of illness for 6 months. Usually, patients with COVID-19 can be cured and discharged from the hospital in 2 to 6 weeks.

Among these patients with early COVID-19 sequelae, fatigue or muscle weakness is the most common, which accounts for 63%, and sleep difficulties are also many, accounting for 26%. In addition to this, 23% also reported anxiety or depression. In people who were more severe in the early stages of infection, chest image abnormalities and lung function impairment were also more common. The findings, published in January 2021 in The Lancet, represent what scientists are aware of the aftermath of COVID-19 in the early days of the pandemic.

A comprehensive analysis of relevant data by Harvard University and other institutions found that more than 50 sequelae of the new crown were identified in the sample size of nearly 50,000 infected people. In addition to fatigue and difficulty breathing, the most common are headaches, attention disorders, hair loss, etc., involving nerves, cardiovascular, lungs and other fields. Moreover, as evidence from clinical observations accumulates, more cases of COVID-19 sequelae have been found around the world. The latest data from the Uk's National Statistics Office in January 2022, using a self-reported sample of nearly 350,000 people, proved that fatigue, breathing difficulties and attention deficits are some of the most common sequelae of COVID-19. In addition, the rate of reported loss of smell also reached 37%. But exactly how many people have the sequelae of the new crown, and how many types of these symptoms are, are still unknown. In addition to identifying several major sequelae, scientists have found that some people are relatively more likely to leave sequelae.

The need for later treatment remains

The most common risk factors are age, severe COVID-19 illness and pre-existing underlying medical conditions. A 2021 comparative study in the British Medical Journal (BMJ) specifically explored what kind of people are more likely to leave COVID-19 sequelae, and of the nearly 190,000 infected people, a total of about 27,000 people have at least one POST-COVID-19 sequelae, accounting for 14% of the total sample size, these people aged 18 to 65 years old, the analysis shows that people older than 50 years old, people who have previously been hospitalized for COVID-19 infection, and people with underlying medical conditions have a greater risk of developing sequelae after infection with COVID-19, but even without these conditions, Compared with other viral lower respiratory diseases, people infected with the new crown also have a higher risk of sequelae, as well as some special sequelae that other viral diseases are less likely to leave, such as high blood clotting, arrhythmias, diabetes, myocarditis, liver abnormalities, etc.

These clinical findings mean that some COVID-19 patients may still need additional medical care after they are discharged from the hospital, and these chronic diseases that have been present for a long time involve different areas and show that the disease is unique. In October 2021, based on previous expert opinions, the World Health Organization has called the symptoms that persist after three months of illness and other unknown causes as sequelae of the new crown, providing some clinical guidance for the global response to the disease. The latest laboratory analysis of the immune system of Patients with COVID-19 sequelae by Australian researchers rarely explores the long-term impact of COVID-19 on people from the perspective of immune indicators, providing some inspiration for improving related treatment and care services. However, the new crown virus is still spreading and mutating, and how the epidemic of variants such as Omi kerong will affect the sequelae of the new crown, these issues related to the course of the new crown pandemic remain to be further observed.

Southern Weekend reporter Wang Jiangtao