周一,香港大學的研究人員證實,在香港出現(xiàn)了全球首例新冠“二次感染”病例。
被證實二次感染的患者為一名33歲香港男子,曾因感染新冠病毒住院治療,4月治愈出院。因香港要求所有抵港人士都必須接受新冠病毒檢測,本月早些時候,該男子自西班牙乘機返回香港接受檢測后再度確診,但屬于無癥狀感染。
相關(guān)研究發(fā)現(xiàn)或?qū)ξ磥淼囊呙缪邪l(fā)項目產(chǎn)生一些影響。自然情況下,在感染新冠病毒并痊愈后,人體會對新冠病毒產(chǎn)生免疫力,而疫苗則是通過模擬自然免疫的過程來實現(xiàn)同樣的目的。二次感染病例的出現(xiàn)不免令人擔心:如果患者在自然免疫力下降到一定程度時可能會被二次感染,疫苗免疫是否會出現(xiàn)同樣的問題?
普遍需求
二次感染病例的出現(xiàn)至少說明了對新冠疫苗需求的普遍性。也表明,衛(wèi)生官員希望通過放任病毒自由擴散進而實現(xiàn)“群體免疫”的策略無法取得其想要的效果。此外,這一病例的出現(xiàn)還表明,新冠治愈患者同樣需要接種疫苗。
作為二次感染問題的研究負責人之一,香港大微生物學系臨床副教授杜啟泓表示:“新冠痊愈患者不應對二次感染的可能性放松警惕,等新冠疫苗上市后,他們?nèi)匀粦撨M行接種。”
調(diào)整預期
杜教授非常謹慎地對疫苗免疫和自然免疫進行了比較,他表示,前者的免疫力應該更強一些。
杜教授說:“根據(jù)疫苗研究報告的相關(guān)數(shù)據(jù),疫苗免疫在效力和免疫時間方面的表現(xiàn)似乎都比自然免疫要好。”
同為香港大學臨床微生物學系臨床副教授的希德哈斯·斯里德哈表示,二次感染病例的出現(xiàn)也“改變了我們對疫苗效力的預期”,因為這一案例表明,任何對新冠病毒的免疫都是有局限性的。斯里德哈教授雖未參與對二次感染的研究,但其一直在從事與新冠病毒相關(guān)的研究工作。
“二次感染者的出現(xiàn)可能是一種信號,說明新冠肺炎和新冠病毒將會長期存在下去。由于其具有造成二次感染的能力,所以沒有什么東西能對其產(chǎn)生100%的免疫力。”斯里德哈說。
但即便疫苗不能誘發(fā)人體對新冠病毒產(chǎn)生100%的免疫力,也能在感染新冠病毒時“有效激發(fā)免疫反應”。
這位33歲的患者在第二次感染新冠肺炎時有一個明顯特征,那就是具有無癥狀的特點,這可能是因為免疫系統(tǒng)已經(jīng)學會了如何抑制這種病毒的結(jié)果。斯里德哈表示,這是個“好消息”,因為這表明,即使疫苗免疫不能防止出現(xiàn)二次感染,也能防止再次出現(xiàn)相關(guān)癥狀。
斯里德哈說:“即便二次感染時出現(xiàn)了相關(guān)癥狀,此前感染過新冠病毒或接種過疫苗的人可能也會實現(xiàn)更好的免疫效果,進而防止出現(xiàn)危重癥狀。只要現(xiàn)在研發(fā)中的疫苗能夠達到這一目的,說實話,就算大功告成了。”
有針對性的疫苗接種
“二次感染者”的出現(xiàn)為我們解答了一些問題,但也提出了一些新的問題。比如:二次感染患者是否具有傳染性就是一個很大的未知數(shù)。
另一個問題則是第一次感染后獲得的免疫力維持了多少時間。該患病男子的兩次感染之間間隔了四個半月,但尚無足夠數(shù)據(jù)表明該個案在更廣泛的人群中是否具有代表性。
杜教授表示,目前尚不了解新冠疫苗的免疫效力能維持多久,而二次感染個案的出現(xiàn)表明,(研究者)在試驗中應注意搜集這方面的數(shù)據(jù)。
更重要的是,本次出現(xiàn)二次感染情況的男子相對年輕,而且身體也比較好,所以他的情況不能代表那些體質(zhì)偏弱的群體,比如老年人或免疫力低下的人群。
杜教授表示:“理論上說,免疫力低下人群二次感染的幾率會更高,但目前我們還沒有這方面的證據(jù)。”
如果新冠病毒會像普通感冒或季節(jié)性流感那樣呈現(xiàn)出周期性傳播的特點,那么,未來的疫苗接種方案可能需要鼓勵體質(zhì)較弱的人群定期接種疫苗。斯里德哈表示,無論如何,疫苗上市之后都應當讓盡可能多的人接種疫苗。
“這名患者可能只是個例……否則二次感染的現(xiàn)象以后可能會經(jīng)常出現(xiàn)。”斯里德哈說。(財富中文網(wǎng))
譯者:梁宇
審校:夏林
周一,香港大學的研究人員證實,在香港出現(xiàn)了全球首例新冠“二次感染”病例。
被證實二次感染的患者為一名33歲香港男子,曾因感染新冠病毒住院治療,4月治愈出院。因香港要求所有抵港人士都必須接受新冠病毒檢測,本月早些時候,該男子自西班牙乘機返回香港接受檢測后再度確診,但屬于無癥狀感染。
相關(guān)研究發(fā)現(xiàn)或?qū)ξ磥淼囊呙缪邪l(fā)項目產(chǎn)生一些影響。自然情況下,在感染新冠病毒并痊愈后,人體會對新冠病毒產(chǎn)生免疫力,而疫苗則是通過模擬自然免疫的過程來實現(xiàn)同樣的目的。二次感染病例的出現(xiàn)不免令人擔心:如果患者在自然免疫力下降到一定程度時可能會被二次感染,疫苗免疫是否會出現(xiàn)同樣的問題?
普遍需求
二次感染病例的出現(xiàn)至少說明了對新冠疫苗需求的普遍性。也表明,衛(wèi)生官員希望通過放任病毒自由擴散進而實現(xiàn)“群體免疫”的策略無法取得其想要的效果。此外,這一病例的出現(xiàn)還表明,新冠治愈患者同樣需要接種疫苗。
作為二次感染問題的研究負責人之一,香港大微生物學系臨床副教授杜啟泓表示:“新冠痊愈患者不應對二次感染的可能性放松警惕,等新冠疫苗上市后,他們?nèi)匀粦撨M行接種。”
調(diào)整預期
杜教授非常謹慎地對疫苗免疫和自然免疫進行了比較,他表示,前者的免疫力應該更強一些。
杜教授說:“根據(jù)疫苗研究報告的相關(guān)數(shù)據(jù),疫苗免疫在效力和免疫時間方面的表現(xiàn)似乎都比自然免疫要好。”
同為香港大學臨床微生物學系臨床副教授的希德哈斯·斯里德哈表示,二次感染病例的出現(xiàn)也“改變了我們對疫苗效力的預期”,因為這一案例表明,任何對新冠病毒的免疫都是有局限性的。斯里德哈教授雖未參與對二次感染的研究,但其一直在從事與新冠病毒相關(guān)的研究工作。
“二次感染者的出現(xiàn)可能是一種信號,說明新冠肺炎和新冠病毒將會長期存在下去。由于其具有造成二次感染的能力,所以沒有什么東西能對其產(chǎn)生100%的免疫力。”斯里德哈說。
但即便疫苗不能誘發(fā)人體對新冠病毒產(chǎn)生100%的免疫力,也能在感染新冠病毒時“有效激發(fā)免疫反應”。
這位33歲的患者在第二次感染新冠肺炎時有一個明顯特征,那就是具有無癥狀的特點,這可能是因為免疫系統(tǒng)已經(jīng)學會了如何抑制這種病毒的結(jié)果。斯里德哈表示,這是個“好消息”,因為這表明,即使疫苗免疫不能防止出現(xiàn)二次感染,也能防止再次出現(xiàn)相關(guān)癥狀。
斯里德哈說:“即便二次感染時出現(xiàn)了相關(guān)癥狀,此前感染過新冠病毒或接種過疫苗的人可能也會實現(xiàn)更好的免疫效果,進而防止出現(xiàn)危重癥狀。只要現(xiàn)在研發(fā)中的疫苗能夠達到這一目的,說實話,就算大功告成了。”
有針對性的疫苗接種
“二次感染者”的出現(xiàn)為我們解答了一些問題,但也提出了一些新的問題。比如:二次感染患者是否具有傳染性就是一個很大的未知數(shù)。
另一個問題則是第一次感染后獲得的免疫力維持了多少時間。該患病男子的兩次感染之間間隔了四個半月,但尚無足夠數(shù)據(jù)表明該個案在更廣泛的人群中是否具有代表性。
杜教授表示,目前尚不了解新冠疫苗的免疫效力能維持多久,而二次感染個案的出現(xiàn)表明,(研究者)在試驗中應注意搜集這方面的數(shù)據(jù)。
更重要的是,本次出現(xiàn)二次感染情況的男子相對年輕,而且身體也比較好,所以他的情況不能代表那些體質(zhì)偏弱的群體,比如老年人或免疫力低下的人群。
杜教授表示:“理論上說,免疫力低下人群二次感染的幾率會更高,但目前我們還沒有這方面的證據(jù)。”
如果新冠病毒會像普通感冒或季節(jié)性流感那樣呈現(xiàn)出周期性傳播的特點,那么,未來的疫苗接種方案可能需要鼓勵體質(zhì)較弱的人群定期接種疫苗。斯里德哈表示,無論如何,疫苗上市之后都應當讓盡可能多的人接種疫苗。
“這名患者可能只是個例……否則二次感染的現(xiàn)象以后可能會經(jīng)常出現(xiàn)。”斯里德哈說。(財富中文網(wǎng))
譯者:梁宇
審校:夏林
Researchers at the University of Hong Kong confirmed the world's first known case of coronavirus reinfection on Monday.
The reinfected person is a 33-year-old man from Hong Kong who was hospitalized with COVID-19 and discharged in April. The man tested positive for the virus again earlier this month after flying back to Hong Kong from Spain. He was asymptomatic the second time he was infected. His reinfection was detected by coronavirus testing that Hong Kong requires of all arriving travelers.
The researchers' findings have several implications for any future coronavirus vaccination program. A vaccine aims to mimic the natural immunity to the coronavirus a human develops after contracting and recovering from COVID-19. The reinfection case is worrisome because it raises the question: if natural immunity wears off to the point that a patient can be reinfected, will immunity from a vaccine diminish too?
Universal need
At the very least, the reinfection finding underscores the universal need for a coronavirus vaccine. It suggests that coronavirus management tactics like the controversial herd immunity approach—in which health officials allow the disease to spread unchecked in hopes that a population will become naturally immune—won't be sufficient. It also suggests that those who contract and recover from COVID-19 shouldn't be exempt from a vaccine.
"Patients who have recovered from COVID-19 should not assume that they will not be infected again," said Kelvin Kai-Wang To, a clinical associate professor in microbiology at the University of Hong Kong (HKU) and one of the researchers who headed the reinfection study. "They should still receive COVID-19 vaccine when it becomes available."
Adjusting expectations
To is careful to draw a likely distinction between the immunity from a vaccine versus the natural immunity gained from an infection: the former is expected to be stronger, To said.
"Based on the data reported from vaccine studies, it's likely that vaccination can induce a more potent and prolonged immunity than natural infection," To said.
At the same time, though, the reinfection case should "adjust our expectations" for a vaccine since it suggests that any immunity to the coronavirus is finite, says Siddharth Sridhar, also a clinical assistant professor in microbiology at HKU. He wasn't involved with the reinfection study but has been conducting research on the coronavirus.
"[The confirmed reinfection] might in fact be a signal that COVID-19 and the virus SARS-CoV-2 is actually here for good, because it is able to establish reinfection, and there will be no such thing as 100% immunity against the virus," Sridhar said.
But even if it can't elicit 100% immunity, a vaccine can be effective in "[priming] our immune response" to a coronavirus infection, Sridhar said.
That "priming" appears to have happened in the instance of the reinfection. The 33-year-old man displayed symptoms the first time he contracted COVID-19, but not the second time, perhaps because his immune system had learned how to suppress the virus. That's "good news," Sridhar said, since it suggests that even if the immunity from a vaccine can't prevent reinfection, it might stop symptoms from flaring up a second time around.
"Even if the reinfection is symptomatic, it is hopeful that an earlier encounter with the virus—or an earlier encounter with a vaccine—will prime our immune responses somewhat and help to prevent a very severe reinfection," Sridhar said. "As long as any of the vaccines currently in development can achieve this, really, mission accomplished."
Targeted vaccination
The reinfection case raises new questions as it answers others. One big unknown is whether the reinfected patient was contagious the second time around.
Another is how long the immunity from his first infection lasted. Four and a half months elapsed between his two coronavirus infections, but there isn't enough data yet to know whether his case is representative of the broader population.
The case suggests that vaccine trials should be monitoring for the duration of protection against the coronavirus, which is still unknown, To said.
What's more, the reinfected man is healthy and relatively young; his experience with reinfection may not translate to more vulnerable population groups like elderly people and immunocompromised people.
"Theoretically, those with poor immune systems may have a higher chance of reinfection, but we don't have the proof yet," To said.
If the coronavirus starts to regularly circulate like viruses that cause the common cold and seasonal influenza currently do, future vaccination programs might encourage more vulnerable populations to receive periodic vaccinations. Regardless, as many people as possible should be vaccinated when a vaccine becomes available, Sridhar said.
"This patient could be an outlier ... or [reinfection] might actually be quite a common occurrence," Sridhar said.