Report by : Gan Yung Chyan, KUCINTA SETIA
Image courtesy : Getty Images
A 33-year-old man in the Hong Kong IT industry was diagnosed with covid for the second time last week. A Hong Kong University (HKU) study found that the patient was the world’s first recorded secondary infection, reflecting that herd immunity may not be able to cut off the spread of SARS-CoV-2. It is possible that like other human coronaviruses that cause colds, SARS-CoV-2 will always exist. Even if antibodies are present, they may not be effective for life, but the symptoms of the patient's second infection may be milder than the first. The expert in charge of the research said that patients can be infected multiple times, making it more difficult to control the epidemic. In the future, the public may be vaccinated once a year, and the pressure on the medical system may be equivalent to facing "two influenza outbreaks." As for those who have recovered, he suggested that they continue to wear masks, maintain social distancing, and vaccinate.
Discharged from square cabin hospital in mid-April
A 33-year-old man in the IT industry was diagnosed with SARS-CoV-2 in March (the 564th case). He developed cough and fever at that time and was discharged from the hospital in mid-April after treatment. He traveled to Spain through the UK this month and arrived on the 15th of this month. He was diagnosed again in Hong Kong, but he was asymptomatic this time. He was treated at AsiaWorld-Expo square cabin hospital and was discharged from the hospital last Friday (21 August).
No symptoms, the sequence of the virus is different from the first time
The research team of the Department of Microbiology of the Faculty of Medicine of the University of Hong Kong found that the patient’s two infections were significantly different in genetic sequencing, with a total of 24 nucleotides different. By comparing the virus gene bank, it was found that the first virus was similar to the virus strain detected in the United States and the United Kingdom in March and April, and the second virus was similar to those in the United Kingdom and Switzerland in July and August.
Based on other data, including the patient’s high viral load after the second diagnosis, four and a half months since the first infection, and the patient’s travel history, the research team determined that the patient was a secondary infection, not that the virus in the body continued after the first infection. The release was the world's first case of secondary infection after recovery.
The research team found that when the patient was infected for the second time, the antibody was not detected at the beginning of the hospitalization, and the antibody was not tested until the fifth day of hospitalization. One of the reasons may be that he did not produce antibodies in his body when he was first infected, or it may be the first time the patient's antibodies produced after the infection gradually decrease over time, so no antibodies can be detected in the initial stage after the second infection.
Possible virus mutation of the S protein, needs further study
The research team also pointed out that the antibody is directed against the S protein of the virus. If the S protein of the virus mutates in the second time, the antibody produced after the first infection of the patient may not be able to recognize the second virus, and the patient was infected twice with the virus. There are 4 amino acid differences on the S protein, including D614G, etc., but the researchers still need to study to determine whether the second infection is caused by the mutation of the virus S protein.
The team pointed out that this case shows that herd immunity cannot halt the spread of SARS-CoV-2. It may spread among humans for a long time like other human coronaviruses, and even if there is a vaccine, it may not provide lifelong immunity. The team also reminded that people who have been infected should also be vaccinated, and those who have recovered should continue to observe infection prevention measures, including wearing masks and maintaining social distancing.
The antibody will expire after about half a year
Medical pressure may face "two influenza outbreaks"
One of the research team members and the clinical professor and assistant dean of the Faculty of Medicine, Hong Kong University School of Medicine, Kong Fanyi, said that the case showed that even if antibodies are present after the first infection, the antibody levels will gradually decline and will become invalid after about six months. Once there is a vaccine, the patient needs to be vaccinated once a year; the long-term existence of the virus may also make the medical system the same as facing "two influenza outbreaks". He also said that there is no seasonality of the SARS-CoV-2. Its all year round spread still needs to be continually observed.
When asked about the impact of the repeated occurrence of SARS-CoV-2 on the long-term services of the hospitals, Lu Zhicong, Director of the Island East Hospital Cluster, said that he could not make a final conclusion. He said, "In the past peak periods of influenza in winter and summer, many elderly were admitted to hospitals but there is no need to cut services significantly. As well as increasing isolation facilities, I am now worried about the high infectiousness of SARS-CoV-2." He added that if the virus continues to appear, the public hospitals may further reduce services, indicating that there are hidden concerns in this regard.
Xu Shuchang, the Chair Professor of the Department of Respiratory System at City University of Hong Kong (CUHK), said that most patients will develop antibodies after infection. The question is how long the antibodies can last. He said, "I believe that the reported case of re-infection this time is rare and the hospital may not continue to explode with such a case in the epidemic but it is too early to make any conclusion."
Source : Ming Pao
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