Coronavirus có thể tồn tại trong nhiều tháng trong não, tim và ruột, Các nghiên cứu chính

Animal virology Bat virome Coronaviridae virus corona COVID-19 Sức khỏe Long COVID Y khoa Medical specialties dược phẩm Sarbecovirus SARS Symptoms of COVID-19 vi rút Zoonoses

Nghiên cứu mới trong tuần này dường như khẳng định mối nghi ngờ rằng coronavirus có thể lây nhiễm sang nhiều bộ phận của cơ thể con người, không chỉ hệ hô hấp của chúng ta. Nó cũng phát hiện ra rằng vi rút đôi khi có thể tồn tại trong cơ thể ngay cả khi các triệu chứng ban đầu của một người đã giảm bớt. Những phát hiện ban đầu có thể làm sáng tỏ tình trạng mãn tính phức tạp được gọi là chứng tắc vòi trứng dài mà một số người sống sót trải qua.

SARS-CoV-2 chủ yếu được coi là một loại virus đường hô hấp, giống như bệnh cúm hoặc các loại coronavirus khác ở người. Trong những trường hợp nhẹ, các triệu chứng cấp tính của nó có xu hướng liên quan đến đường hô hấp trên, trong khi những trường hợp nghiêm trọng hơn thường liên quan đến nhiễm trùng phổi và viêm phổi. Nhưng bằng chứng từ phòng thí nghiệm và trên bệnh nhân cho thấy vi rút có thể di chuyển khắp cơ thể và lây nhiễm sang các mô khác, nhờ vào các thụ thể mà nó sử dụng để chiếm đoạt tế bào. Ví dụ, gần đây, các nhà khoa học đã tìm thấy bằng chứng cho thấy coronavirus có thể dễ dàng lây nhiễm chất béo và các tế bào miễn dịch.

The scientists behind this new research, mostly from the National Institutes of Health, say theirs is the most comprehensive look so far at how well the coronavirus can infect the various parts of the human body and brain. To do this, the researchers performed complete autopsies on 44 people who had been infected with the coronavirus. In all but five cases, the infection was directly implicated in the person’s death.

Overall, the team found copious signs of the coronavirus beyond the respiratory tract, both early and late into the infection. Its presence was definitely highest in the airways and lungs. But they also found evidence of infection in the cardiovascular tissue of nearly 80% of patients; in the gastrointestinal tissue of 73 % of patients, and in the muscle, skin, adipose (fat), and peripheral nervous tissue of 68% of patients. Across all 85 body parts and bodily fluids they studied, the virus could be found—at least some of the time—in 79 of them, including the brain. And they found traces of viral RNA throughout the body and brain months after symptoms had begun, up to 230 days in one patient’s case.

“Our data prove that SARS-CoV-2 causes systemic infection and can persist in the body for months,” the authors wrote in their paper, which was released as a preprint Sunday but is under review for publication in the journal Nature, according to Bloomberg News.

There are important limitations to this research. For one, the cases obviously tended to involve people severely ill with covid-19. But even in the few cases where someone had mild or no covid-related symptoms, the virus could still be found throughout the body, the authors noted. The study was also conducted between April 2020 to March 2021, a period of time when relatively few people were vaccinated. So it’s possible that those with some immunity may prevent the virus from infecting the body as thoroughly as it did in these patients (there was no mention of anyone being vaccinated in the paper). The emergence of several new variants of the virus, such as Delta and Omicron, since March may further complicate the picture.

All that said, the findings give us a clearer picture of how acute infection by SARS-CoV-2 works and how it could continue to cause trouble after the initial illness seems to resolve. Some experts believe that at least some cases of long covid can be attributed to persistent infection. But while these findings provide strong evidence that long-term infections do happen, they also raise new questions.

For instance, the team found little evidence that the presence of the virus outside the lungs was associated with direct inflammation or other virus-related injury to cells, even in persistent infections. That’s key because inflammation is one of the most common ways that the body can damage itself chronically, and many experts believe that it plays a major role in long covid symptoms. In some cases of persistent infection, the authors noted, the virus may have been too defective to keep replicating, which may explain why the body didn’t respond to it like a typical infection. This finding doesn’t exclude the possibility that the virus is still causing harm when it lingers in the body, but it adds a new wrinkle to the mystery of long covid that scientists will have to keep studying.