周末，墨西哥总统安德烈斯·曼努埃尔·洛佩斯·奥夫拉多尔表示，他的检测结果呈阳性新冠肺炎(新型冠状病毒肺炎)这是他第三次对抗病毒。
洛佩兹·奥布拉杜尔在2013年心脏病发作，在推特上写道周日，他说他的病情很轻，而且“我的心脏是百分之百的”
研究表明，大多数美国人至少感染过一次COVID，但越来越多的人感染过多次。
疾病控制和预防中心没有提供再感染数据，但州级数据描绘了一幅不同的画面。
来自的数据纽约州卫生部门显示总感染的大约8.5%是再感染。在华盛顿州，截至2022年10月，所有感染中约有1%是再感染，这是可获得的最新数据州卫生部说道。
专家表示，再感染是由多种因素造成的，包括免疫力下降和更多可传播的变异，但对于那些容易出现COVID严重并发症的人来说，风险最高。
再次感染的风险有多大?
有几个因素与一个人再次感染的可能性有关。
截至3月19日，疾控中心数据显示未接种疫苗人群的新冠肺炎病例率为每10万人中81.11人，比完全接种疫苗和加强免疫人群的每10万人中25.81人高出三倍多。
虽然完全接种疫苗并接种二价加强疫苗可以降低再次感染的风险，但研究表明，免疫力确实会随着时间的推移而减弱。
此外，如果一个人生活在社区传播水平高而传播水平低的县，再感染的机会就会增加。
另一个疾病控制中心的研究观察了之前被感染的重要工人。研究发现，未接种疫苗、首次感染后不经常戴口罩以及是黑人都增加了再次感染的风险。
波士顿儿童医院(Boston Children's Hospital)的流行病学家兼首席创新办公室(chief innovation office)主任、美国广播公司新闻撰稿人约翰·布朗斯坦(John Brownstein)博士说，“事实是，进入疫情已经三年了，我们知道感染取决于多种因素，包括之前的免疫力。”。“这不是不可能的，特别是在很长一段时间内，免疫力下降，无论是通过感染还是通过疫苗接种。”
他继续说道，“我们见过许多人感染了两次、三次甚至四次COVID。和行为有关。这与掩蔽或旅行有关。”
变体的作用
目前，XBB.1.5是omicron的子变体，占美国新COVID病例的大多数，疾控中心数据显示。
与此同时，另一个亚变异体XBB.1.16在印度首次发现，占新病例的近10%。
世界卫生组织新冠肺炎技术负责人Maria van Kerkhove博士说，在一次新闻发布会上说"在刺突蛋白上有一个额外的突变，在实验室研究中显示传染性增加."
目前，没有数据表明XBB.1.16导致更严重疾病、住院或死亡的增加。
布朗斯坦说，保持警惕很重要，因为一种新的变种可能会改变再次感染的可能性。
布朗斯坦说:“我们仍然担心在变异问题上遇到难题。”。“到目前为止，我们看到了一条非常可预测的奥米克隆前沿道路，但我们有可能会看到一些完全出乎意料的东西，可能会挑战我们从以前的感染和疫苗中获得的潜在免疫力。”
再感染危险吗?
布朗斯坦说，关于COVID再感染是否会增加慢性疾病的风险，一直存在相互矛盾的数据。然而，专家称，既往感染确实提供了一些保护。
“归根结底，拥有潜在的免疫力是有益的...某种程度的免疫将为新的变异提供一些交叉保护，”他说。
布朗斯坦说，那些更有可能出现新冠肺炎严重并发症的人仍然有风险，包括老年人和免疫功能低下的人。
此外，每一次COVID感染都会增加某人患长期COVID的风险，当一个人的COVID症状持续三个月或更长时间时，就会发生长期COVID。
“我们担心的不仅仅是住院和死亡;这是COVID的长期慢性影响，”布朗斯坦说。“每次你被感染时，都有可能出现持续时间更长的症状，这一点我们已经看到了强有力的数据支持，其中一些影响会对人群产生多么大的削弱作用。”
After Mexican president tests positive for 3rd time with COVID, what do we know about reinfection?
Over the weekend, Mexican President Andres Manuel Lopez Obrador said he had tested positive forCOVID-19, his third time battling the virus.
Lopez Obradour, who suffered a heart attack in 2013,wrote on Twitteron Sunday that his case is mild and that "my heart is at 100 percent."
Studies suggest that most Americans have been infected with COVID at least once but a growing number have been infected multiple times.
The Centers for Disease Control and Prevention does not provide reinfection data but state-level data paints a varied picture.
Data from theNew York State Department of Healthshows that about 8.5% of total infections are reinfections. In Washington state, about 1% of all infections are reinfections as of October 2022, the latest date for which data is available, thestate health departmentsaid.
Experts say reinfection is caused by a number of factors -- including waning immunity and more transmissible variants -- but the risk is highest for those who are vulnerable to serious complications from COVID.
What is the risk of being reinfected?
There are several factors tied to a person's likelihood of being reinfected.
As of March 19,CDC datashows the COVID-19 case rate for unvaccinated people was 81.11 per 100,000 -- more than three times higher than the rate of 25.81 per 100,000 among people fully vaccinated and boosted.
While being fully vaccinated and getting the bivalent booster shot can lower the risk of reinfection, studies have shown that immunity does wane over time.
Additionally, the chances of reinfection increases if a person lives in a county with high community transmission levels versus low transmission levels.
Anotherstudy from the CDClooked at essential workers who had previously been infected. It found that being unvaccinated, not frequently wearing a mask since first infection and being Black all increased the risk of being reinfected.
"The reality is three years into the pandemic, we know that infection is dependent on a variety of factors, including prior immunity," said Dr. John Brownstein, an epidemiologist and chief innovation office at Boston Children's Hospital and an ABC News contributor. "It's not impossible especially over a long period of time, with immunity waning, whether that's through infection or through vaccination."
He continued, "We've seen many people with two, three, even four times COVID infection. It's related to behavior. It's related to practices around masking or travel."
Role of variants
Currently, XBB.1.5, a subvariant of omicron, makes up the majority of new COVID cases in the U.S.,CDC datashows.
Meanwhile, another subvariant, XBB.1.16, which was first detected in India, makes up nearly 10% of new cases.
Dr. Maria van Kerkhove, the World Health Organization's technical lead for COVID-19,said at a briefing that the variant"has one additional mutation in the spike protein, which in lab studies showed increased infectivity."
Currently, no data suggests XBB.1.16 causes an increase in more severe illness, hospitalizations or deaths.
Brownstein said it's important to stay vigilant because a new variant could change how likely reinfection is.
Mexico's President Andres Manuel Lopez Obrador speaks during a news conference at the Secretariat of Security and Civilian Protection in Mexico City, March 9, 2023.
Henry Romero/Reuters, FILE
"We still have concern about being thrown a curveball when it comes to variants," Brownstein said. "So far, we're seeing a pretty predictable path along this omicron front but it is possible we'll see something completely out of left field that could challenge that underlying immunity that we've had from previous infections and vaccines."
Is reinfection dangerous?
Brownstein said there has been conflicting data on whether or not COVID reinfection raises the risk of chronic illness. Having a prior infection, however, does offer some protection, experts say.
"At the end of the day having the underlying immunity is beneficial ... some level of immunity will provide some cross protection to new variants," he said.
Brownstein said there is still a risk for those who are more likely to have severe complications from COVID-19, including the elderly and those who are immunocompromised.
Additionally, every COVID infection increases the risk of someone developing long COVID, which occurs when a person has ongoing symptoms of COVID lasting three months or longer.
"The concern that we have is not just about hospitalizations and deaths; it's the long-term chronic impact of COVID," Brownstein said. "And each time that you get infected, there's a potential for having longer-lasting symptoms, which we've seen strong data support, how debilitating some of these impacts can be for the population."
