COVID-19 "secondary infection" requires vigilance but no need to panic

Recently, a case of "secondary infection" of the new coronavirus was discovered in the United States, which is also the fourth case of "secondary infection" of the new coronavirus in the world. Why do patients with new coronary pneumonia experience "secondary infection" after recovery? Is it the same as "re-positive"? The frequent occurrence of "secondary infection" of the new coronavirus in a short period of time, does it mean that the survival time of antibodies in the bodies of patients with new coronary pneumonia after recovery may be very short? What impact will this have on future vaccine development and epidemic prevention and control work?

Different from the new crown "re-positive"

"Re-positivity does not mean that the patient has been reinfected with the virus, but is a manifestation of residual virus in the body. If there is a virus, there will be corresponding antibodies." Huang Bo, professor at the Department of Immunology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and vice president of the Chinese Immunology Society, believes that these four patients could not detect relevant antibodies against the new coronavirus, and it can be determined that they were infected again after recovery, rather than "re-positivity."

Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention, believes that although the cases discovered this time have some mutations in the genetic sequence of the virus strain and are not caused by the same strain, it is more likely that the human body's immune protection effect is not that long-lasting, resulting in "secondary infection."

Zhang Wenhong, director of the infectious department at Huashan Hospital affiliated to Fudan University, believes that these cases are not "re-positive" in the general sense and further research evidence is needed. "The phenomenon of 'secondary infection' is similar to the 'off-target' immune protection produced by attenuated live vaccination. The symptoms of this kind of infection are often mild, and high levels of antibodies are produced quickly."

No impact on vaccine development

At present, medical and research institutions around the world are still unclear about how strong the immunity of recovered COVID-19 patients is, how long it can last, or how much effect antibodies can have in preventing "secondary infection."

Yang Zhanqiu, a professor at the Institute of Virology, School of Medicine, Wuhan University, said that it is normal for different types of viruses to be "secondarily infected". Generally, the greater the amount of virus in the human body, the higher the antibody level and the longer it lasts, and there is a positive relationship between the two.

Zeng Guang, former chief scientist of epidemiology at the Chinese Center for Disease Control and Prevention, said that we now need to observe whether "secondary infection" will develop into a common situation, such as tens of thousands of patients being "secondarily infected" and new developments. At present, it is not clear how much impact it will have on vaccines. The virus mutations mentioned now are only small mutations and will not have a big impact on vaccines and prevention and control measures. "But we need to pay attention to this situation and pay attention to whether the condition is getting worse, whether there are critically ill patients, and how high the proportion is. If there are no major changes, we only need to be vigilant and do not need to change the current prevention and control measures and vaccination strategies for the time being."

Relevant immunology experts believe that even if a "secondary infection" occurs and the vaccine needs to be updated, it is not difficult to achieve with current technology, so there is no need to panic. Moreover, based on current understanding, the mutation of the new coronavirus is not as fast as that of the influenza virus.

Or normalization but no need to panic

Some immunology experts believe that "secondary infection" of the new coronavirus may become a normal phenomenon, and "secondary infection" is more likely to occur in areas with a large infection range and a large number of infections.

Zhang Wenhong said: "Although it is only an isolated case at present, 'secondary infection' is related to the durability of immunity, as well as the duration of protection that future vaccines can provide and the interval between repeated vaccinations. This issue should be observed in a larger population after infection. Currently, more than 23 million people in the world have been infected with the new coronavirus. If 'secondary infection' is established, then in areas where the new coronavirus is highly prevalent and prevalent, reinfection may become the norm."

Previously, cases of "secondary infection" were found in many places. The common feature of these cases is that the symptoms are relatively mild. In contrast, the second patient in the United States was in a more serious condition after the "secondary infection" and needed hospitalization and oxygen therapy.

Liang Lianchun, director of the Second Department of the Infection Center of Beijing You'an Hospital affiliated to Capital Medical University, revealed in an interview with the media that more recovered patients of COVID-19 may suffer from "secondary infection" in the future, but people do not need to be too nervous, as the symptoms of "secondary infection" are usually milder than the first infection.

In response to the frequent cases of "reinfection" of the new coronavirus, WHO spokesperson and virologist Margaret Harris said that conclusions cannot be drawn based on just one case, and people do not need to be afraid or panic about it.

Regarding the prevention of "secondary infection", Liang Lianchun said, "People should take good personal protection in their daily lives and avoid going to high-risk places and contact with high-risk groups as much as possible. In addition, vaccination against COVID-19 is also an effective way of prevention."