Guangzhou detects XBB, BQ.1 in arrivals, no social transmission yet

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Recently, new strains of Omicron such as XBB and BQ.1 have raised concerns. Are the new strains detected in Guangzhou? Are people who have been infected with omicron still protected against XBB and BQ.1? On January 6, Li Feng, deputy director of the Institute of Infectious Diseases of the Eighth Hospital of Guangzhou Medical University, was interviewed by Yangcheng Evening News on these hot issues.

Guangzhou detected XBB, BQ.1 in the arrivals

Not spread in the community

Q: What are the main branches of the virus in the infected people admitted to the eight hospitals in the current round of the epidemic?

We have detected XBB, BQ.1 and other strains of virus in some incoming patients, but the number is very small and has not spread in the community.

After infection with BA.5.2 and BF.7

Is there any cross-protection against XBB and BQ.1?

Q: What is the cross-protection effect of the antibodies produced after BA.5.2 and BF.7 infection on XBB and BQ.1? Some experts say that BQ.1 is a branch of Omicron, and people who have been infected with Omicron are not easy to be infected with BQ.1 again, is that correct?

Feng Li: From the basic research data published in foreign countries, the cross-protection against BQ.1 and XBB is reduced by more mutations after infection with BA.5 or BF.7, analyzed from the perspective of neutralizing antibodies.

BQ.1 evolved from BA.5 and is its daughter virus. According to the available international published data, the serum from infection with Omicron still has some neutralization protection against “hellhound” and therefore protects against “hellhound” attacks in the short term. The prevalent strain of BA.5 in Guangzhou is very close to Cerberus, so it is inferred that it is unlikely to be attacked by Cerberus again in the short term after recovery.

However, in addition to the “first door” of neutralizing antibodies, we also have the protection of T-cell immunity, which is the “second door” of protection. T cells have a longer-lasting immune memory and recognize more epitopes because they recognize the virus differently. Therefore T cells can form some protection against XBB and BQ.1 viral infections. Even if they are secondarily infected, the symptoms will be milder and the virus will have a faster clearance time. There may be people who are already infected but do not show symptoms and do not feel that they have been infected, which is also a symptom protection.

Q: A study by your team and Prof. Xiaoping Tang’s team in 2021 had found that specific protective immunity against new coronavirus can be maintained for more than 1 year, what strain was studied at that time? Has a similar study been done for Omicron-infected patients? What are the results?

Feng Li: At that time we did a follow-up of infected patients with wild-type strains of the virus and found at that time that protective immunity persisted after 1 year of follow-up. Then we also did a follow-up of delta virus and found the same pattern as the wild type.

Recently we have also followed up Omicron-infected patients for 3-6 months, and the follow-up has not yet reached as long as the two previous strains. In the short term, the changes in their body levels of neutralizing antibodies and T-cell immunity do not show significant differences from the wild-type and delta viruses.

But the virus is changing much faster now than it did back then, most of the population is vaccinated, etc., are new variables, and it will take time to see what actually happens.

From the principle of immunology, after infection, neutralizing antibodies are like the body’s gatekeeper, “rejecting” the recognized virus, when the virus has mutated a little, it will still be “recognized”, at this time can still protect the body from infection. However, when the virus mutates more and more, the neutralizing antibodies will think they have “not seen” and “let go”, and then reinfection will occur.

However, T-cell immunity does not work by “seeing” the virus alone, but by expressing its own proteins after the virus has infected the cell and displaying the “I’ve been invaded” sign on the cell surface, and T-cell immunity can recognize the “arms” and “legs” of the virus. T-cell immunity recognizes the “arms” and “legs” of the virus and removes the virus from the infected cells. In this way, the T cells prevent the virus from spreading further in the body, thus protecting us in this way.

So, after an infection, the more the virus mutates, the easier it is to break through the protection of neutralizing antibodies and the more likely we are to get infected; but after an infection, with the basal protection of T-cell immunity, there is a certain amount of protection against severe disease, that is, re-infection, usually with less severe symptoms.

How to easily self-test for re-positive or secondary infection?

Antigen testing for 3 consecutive days!

Q: How can I tell if I have a secondary infection or a re-infection?

Feng Li: To simply distinguish between a repeat and a secondary infection, the public can use home antigen testing reagents. After a week or two weeks of complete recovery, if a secondary infection is suspected, the antigen agent can be used to test for three consecutive days. If the test result is positive, it may be a secondary infection. A repeat positive is usually very difficult to detect, and even if it is detected, it will not be continuous all the time.

In fact, there is a big difference between a repeat and a secondary infection.

Firstly, pathogenetically speaking, a repeat positive is a delayed discharge of the remaining virus in the infected person’s body, which comes from the first viral infection. In contrast, secondary infection is the infection of a new coronavirus from another source after recovery, and the virus comes from an external infection.

Secondly, the timing of the infection is mainly within two weeks after recovery from the infection (undetectable virus), and the virus fragment is detected by nucleic acid PCR. Secondary infections take a longer period of time, usually several months. In healthy individuals, secondary infections can only occur when immune protection becomes low. In the case of a new viral variant, the variant can break the immune protection formed by the first infection and a secondary infection is likely to occur.

Third, the symptoms are different. The symptoms have all recovered and improved during the re-positive stage, no medical treatment intervention is needed, and the viral nucleic acid is in a state where it is occasionally detectable. Because antigens are less sensitive than nucleic acids, they may not be detected with antigen detection reagents. However, secondary infections are different in that the virus goes through a complete cycle of infection, including rising viral load, plateau maintenance, decline and disappearance, so the concentration of virus in secondary infections will be very high and antigen will be detected continuously, usually with very obvious two bars and also with uncomfortable symptoms.

Q: Why are some people still not positive now?

Feng Li: Theoretically, the whole group is susceptible. But in reality, it is true that some people are not infected with the new coronavirus. In addition, the entire population is not tested for nucleic acid on an ongoing basis across the board, and some people may be unaware of their infection. In clinical practice, we did see cases where in 2020, a family of four had both regular and critical types, and rather strangely, one member had the virus in her body for an extremely short period of time, only three days, and no symptoms, just a little mild discomfort, and no antibodies to the virus could be measured afterwards; she was nucleic acid positive and had been infected, but had no symptoms, and her immune system did not leave a mark. The fact that some people currently do not show being infected by the virus may also be related to practices such as genetic background, vaccination rates, and cutting off sources of infection by maintaining social distance. Just because you haven’t contracted the virus yet doesn’t mean you won’t get it afterwards.

On the same day, Li Yueping, director and chief physician of the ICU of the Infectious Disease Center of the Eighth Hospital of Guangzhou Medical University, answered questions from reporters on topical issues

XBB does not specifically target the cardiovascular or intestinal tract

No need to blindly stock up on drugs

Q: Are there any patients with the XBB strain among the patients admitted to the hospital? Do you have any advice for the recent stockpiling of drugs in the market due to the XBB strain attacking the intestinal system?

LiYuePing: At present, XBB strain has been found among the newly infected patients imported from abroad admitted to City 8 Hospital; however, it has not been found among the locally infected patients. At present, XBB has gradually replaced other subtypes of Omicron as the dominant strain in foreign countries. With the optimization and adjustment of immigration control measures, there may also be native infected patients with subtypes of XBB and BQ.1 later.

Some citizens are stocking up on norfloxacin and diarrhea medicine. In fact, XBB is still a viral infection, the route of infection is still through the ACE2 receptor, and the performance after infection is similar to the previous strain. Diarrhea has actually always been present in the top ten symptoms of XBB, and there is no evidence that XBB infection produces particularly powerful symptoms of diarrhea.

The need to ensure safety when taking paxlovid

Q: What are the precautions for residents taking paxlovid at home? Are there any side effects to be aware of while taking the drug? Are there any drugs that should not be taken together?

Yueping Li: First of all, it should be clear that Paxlovid is a prescription drug and must be taken under the guidance of a doctor. It should not be taken by pregnant women, patients under 12 years old, patients with renal insufficiency (glomerular filtration rate less than 30), or patients with severe hepatic insufficiency. Secondly, most patients taking Paxlovid are at high risk of concurrent coronary heart disease, diabetes, hypertension, etc. Be sure to look for concurrent statin lipid-lowering drugs, anti-platelet aggregation, anticoagulant drugs, diphenhydramine antihypertensive drugs, immunosuppressants, or amiodarone, anti-infective drugs, etc. Before taking the medication, it is important to consult your doctor about which drugs need to be reduced and which drugs should be stopped, very carefully, and must be taken under the supervision and guidance of your doctor.

When it comes to the time of taking, Paxlovid can be taken either with meals or after meals. Special attention should be paid to common digestive tract reactions side effects, some elderly people with fever and poor mental health and digestive tract reactions when taking Paxlovid with or without nausea, vomiting and other reactions. People are asking if it is possible to grind and eat the medicine if it is difficult to feed it. Although the instructions of the drug itself say to swallow the whole tablet, according to the current guidelines, it is still effective to eat nematavir and ritonavir within 5 minutes after grinding and mixing them into a suspension.

Setting up a convertible ICU to improve bed turnover

Q: Are there many patients currently being transferred out of the ICU? How can the bed turnover rate be improved?

A: Some time ago, more than 110 patients were admitted to the ICU, and more than 30 cases are currently in the hospital. 70 patients have been successfully transferred out of the ICU, and some of them have gone to the general ward and some have returned to their families or community hospitals. The high number of patients transferred out is due to the fact that the hospital has more than 100 convertible ICU beds. If a patient has met the criteria for ICU transfer, he or she can be monitored in a general ward with only simple respiratory support, leaving ICU resources for those in greater need. Some elderly people are currently not in as good a state of consciousness or are experiencing muscle weakness after infection and can be transferred down to community hospitals for rehabilitation.

Elderly people’s symptoms are not as obvious as young people

The people around you must pay more attention

Q: What is the current direction and strategy for treating serious illnesses in Guangzhou? If the task of preventing serious illnesses is delegated to a community level, can primary care doctors accept such a task?

LiYuePing: At present, Guangzhou’s critical care patients are mainly elderly people, especially those with underlying diseases. For this reason, we adopt a stratified and graded strategy, admitting critical care patients to internal medicine departments such as respiratory medicine, cardiovascular medicine, neurology, etc. We also combine respiratory, infection and critical care specialists to check in together, and customize personalized treatment plans for critical care elderly patients.

The first stage is from the first day to the fifth day after the onset of the disease, which is also known as “5 days is a watershed for elderly patients with new coronary heart disease”, if it improves, the disease will gradually recover, otherwise the condition will go downhill. At present, it seems that severe illness in the elderly occurs more often on the fourth to sixth day.

The symptoms of neocoronavirus infection in the elderly are not as obvious as in younger people. For example, some elderly people may have an elevated temperature, but they are not aware that they have a fever, and they may even experience “silent hypoxia,” so it is important for those around them to watch for extreme fatigue, confusion, loss of appetite, and reduced speech. To prevent serious illnesses in the community, community doctors need to be able to recognize them. We are currently providing homogeneous training to community doctors so that they can recognize danger signs in a timely manner, so that early diagnosis and treatment can be achieved and the progression of serious illnesses in the elderly can be stopped.