"Double positive" appears in many places? Zhang Wenhong reminds: These three types of people should pay special attention!

Recently, many people posted their positive antigens online, claiming to have tested positive for the virus twice, and some netizens even said that “the whole family has tested positive for the virus twice”.

The topic #新冠# also once again topped the Weibo hot search list, attracting attention.

Latest report from China Centers for Disease Control

"Arcturus" reported 42 cases

On April 22, the Chinese Center for Disease Control and Prevention announced the latest situation of the novel coronavirus infection epidemic across the country.

Compared with the data released by China CDC on April 15, 275 new local key variants were discovered from April 14 to April 20.

Since December 9, 2022, the number and positive rate of nucleic acid tests for the new coronavirus reported by various provinces have shown a trend of first increasing and then decreasing. The number of positive cases reached a peak (6.94 million) on December 22, and then fluctuated downward, dropping to 2,661 cases on April 20, 2023; the positive rate reached a peak (29.2%) on December 25, 2022, and then fluctuated downward, reaching 1.7% on April 20, 2023.

From September to early December 2022, the number of influenza-like cases (body temperature ≥38℃, accompanied by cough or sore throat) in influenza sentinel hospitals across the country remained stable at around 100,000 per week, and the ratio of influenza-like cases to outpatient (emergency) visits fluctuated between 2.7% and 3.6%. In the 7th week of 2023 (February 13-19), the proportion of influenza-like cases (1.8%) began to show an increasing trend, and in the 10th week (March 6-12), it reached a peak (9.1%) and then began to decline continuously. In the 15th week (April 10-April 16), the proportion of influenza-like cases dropped to 5.8%.

It is worth noting that 42 cases of XBB.1.16 were detected. Previously, last week (April 15), the Chinese Center for Disease Control and Prevention released data showing that a total of 15 cases of XBB.1.16 were detected (the first time in my country), and this week the number has increased to 42.

XBB.1.16 is a recombinant strain of the novel coronavirus Omicron, belonging to the XBB family, and is popularly named "Arcturus". The proportion of XBB.1.16 in the sequences reported in India has increased rapidly since March, and it has now become the main prevalent strain in India. Among the variants currently prevalent in the United States, XBB.1.5 is still the main one, but the proportions of XBB.1.16 and XBB.1.9.1 have increased recently. As XBB.1.16 is prevalent in some Asian countries, the proportion of XBB.1.16 in recent imported cases in my country has increased.

But people do not need to worry too much. On April 21, the National Center for Disease Control and Prevention stated that the level of XBB.1.16 among domestic cases in China remained extremely low and had not formed a transmission advantage.

In general, BF.7 and its subbranches are the dominant strains in Beijing and Inner Mongolia; the two evolutionary branches in Hainan, Shanxi and Tianjin are basically the same; and BA.5.2 and its subbranches are the dominant strains in other provinces.

When will a secondary infection of the new coronavirus occur?

Who is more likely to be infected?

Many people care

When will a secondary infection of the new coronavirus occur?

Who is more likely to be infected?

April 20

Director of the National Center for Infectious Diseases,

Director of the Department of Infectious Diseases, Huashan Hospital Affiliated to Fudan University

Zhang Wenhong at the "Infection Immunity Summit Forum"

Provided an answer

When will secondary infection occur?

Zhang Wenhong introduced that according to the data, if the new coronavirus mutates, secondary infections will slowly appear after 6 months, generally on a small scale . However, if the next wave of virus mutations effectively breaks through the immune barrier formed by the human body to fight the previous wave of viruses, the second wave will form an infection peak.

Zhang Wenhong said that in response to the second infection of the new crown, it is necessary to pay attention to vulnerable groups, continuously monitor and warn, make good drug reserves, and respond quickly to the arrival of any mutant strains. It is recommended that vulnerable groups (re-vaccinate) after 6 months, and both bivalent and monovalent vaccines are acceptable.

Will people who were not infected in the first round be infected a second time?

Two waves of the COVID-19 epidemic have occurred in many countries and regions around the world (including Taiwan, Japan, Singapore, the United States, and the United Kingdom).

Zhang Wenhong explained that there are two main situations for secondary infection: one is that the immunity of people who were infected in the first wave of the epidemic gradually declines, and the other is that people who were not infected in the first wave of the epidemic are infected in the second wave of the epidemic. According to monitoring data, many of the new crown infected people in my country are in the latter situation.

Zhang Wenhong quoted Fauci, an American infectious disease expert, as saying, "The new coronavirus will find everyone. When the barrier of herd immunity is established, the new coronavirus will look for people who have not yet established an immune barrier. Therefore, countries that have better control over the first wave of infection will have a higher peak in the second wave of infection."

If the virus mutates, do the antibodies in the body still provide protection?

"At present, the several new coronavirus variants in China are mainly BA.5, BF.7, and XBB. XBB accounts for 90% of the strains prevalent in the United States and 50% in Hong Kong, China. The proportion in mainland China will gradually increase in the future. It will shorten the protection time of effective neutralizing antibodies from 6 months to 4-5 months. However, neutralizing antibodies still have a protective effect. At 6 months after infection, the protection rate of neutralization antibodies is still 50%. " Zhang Wenhong said.

Zhang Wenhong also said, "If no new virus variants appear after XBB, then this wave of infection may slowly fade away, and we will continue to see low-level, recurring epidemics. If new variants continue to appear after XBB, then there will be a new wave of infection. But we don't know where the most virulent strain is."

Therefore, our country is actively monitoring. "On the one hand, we are monitoring whether there are new variants entering, and on the other hand, we are monitoring whether the new variants cause more severe illness."

Will the new coronavirus be like the flu in the future?

Zhang Wenhong said that many subtypes of influenza appear every year, with genetic recombination, more variants and greater volatility; while the subtypes of the new coronavirus are replacement-type, with the latter replacing the former and without genetic recombination.

If nothing special happens, the new coronavirus will become more and more like the existing coronaviruses and will always exist, but its presence will not be as strong. Whether it will eventually become influenza depends on the characteristics of its later mutations.

In the face of secondary infection, these groups of people should pay special attention!

In the face of secondary infection, we still need to pay attention to key groups. A Danish study involving 7,000 people analyzed secondary infection and found that Omicron is very likely to cause secondary infection, while other strains are less likely to cause secondary infection. Women, young people, and medical workers are more likely to be infected again.

Zhang Wenhong reminded that both international and domestic data show that people who were not infected in the first wave of the COVID-19 epidemic are at higher risk of infection when the second wave of infection comes. As for secondary infection, people aged 60 and above and those who have not been vaccinated are at higher risk of infection.

On March 28, the World Health Organization (WHO) Strategic Advisory Group of Experts on Immunization (SAGE) revised the roadmap for the priority use of the new crown vaccine. Healthy children and adolescents aged 6 months to 17 years are low-priority groups. SAGE recommends that countries consider whether to vaccinate them with the new crown vaccine based on specific circumstances; the elderly, young people with serious comorbidities (such as diabetes and heart disease), people with weakened immunity, pregnant women and frontline health workers are high-priority groups and should receive a booster immunization 6 or 12 months after the last vaccination.

Zhang Wenhong said that if the vaccine is given again after 6 months, the antibody level will start to rise again, thus preventing infection; after the antibody level is adjusted high, the immune system will be easier to be re-awakened, thereby significantly reducing the risk of infection.

In addition, Zhang Wenhong said that it is still necessary to reserve small molecule antiviral drugs. At the same time, a very important measure is to establish a model that can provide early treatment within 48 hours. Citizens can go to the nearest community health center to test antibodies or antigens and receive corresponding drugs.

"I believe that by constantly monitoring, issuing early warnings, making good drug reserves, and responding quickly to the arrival of any mutant strains, we will definitely be able to get ahead of the next wave of the epidemic," said Zhang Wenhong.

Source: People's Daily Online Science Comprehensive Qianjiang Evening News, China Center for Disease Control and Prevention, Health Times, Beijing Daily, Zhejiang News