自2020年12月以来，已经发现了几种冠状病毒变种，目前正在调查中. Each new variant raises questions: Are people more at risk for getting sick? Will the COVID-19 vaccines still work? Are there new or different things you should do now to stay safe?

Lisa Maragakis, M.D., M.P.H., senior director of infection prevention, Stuart Ray, M.D., vice chair of medicine for data integrity and analytics, and Robert Bollinger, M.D., M.P.H., the Raj and Kamla Gupta Professor of Infectious Diseases, all of Johns Hopkins Medicine, are experts in SARS-CoV-2, the virus that causes COVID-19. They talk about what is known about these new variants, and answer questions and concerns you may have.

Coronavirus Mutation: Why does the coronavirus change?

当病毒的基因发生变化或突变时，病毒就会发生变异. 雷说，像冠状病毒这样的RNA病毒的本质是逐渐进化和改变. “Geographic separation tends to result in genetically distinct variants,” he says.

病毒的突变——包括导致COVID-19大流行的冠状病毒——既不是新的，也不是意外的. Bollinger explains: “All RNA viruses mutate over time, some more than others. For example, flu viruses change often, which is why doctors recommend that you get a new flu vaccine every year.”

What is a variant of concern?

Coronavirus variants are classified 按世界卫生组织(WHO)和疾病控制与预防中心(CDC)等组织的不同类别分类.

A variant of interest is a coronavirus variant that, compared with earlier forms of the virus, has genetic characteristics that predict greater transmissibility, evasion of immunity or diagnostic testing, or more severe disease.

A variant of concern has been observed to be more infectious, 并且更有可能在接种过疫苗或以前感染过的人身上引起突破性感染或再感染. These variants are more likely to cause severe disease, evade diagnostic tests, or resist antiviral treatment. Alpha, beta, gamma, SARS-CoV-2冠状病毒的δ型和组粒型变体被归类为值得关注的变体.

A variant of high consequence is a variant for which current vaccines do not offer protection. As of now, there are no SARS-CoV-2 variants of high consequence.

Will the COVID-19 vaccines and boosters work on the new variants?

Ray says, “有来自实验室研究的证据表明，由当前疫苗驱动的一些免疫反应对其中一些变体可能不太有效. Those eligible for COVID-19 boosters should obtain them for added protection against infection and severe disease.

“The immune response involves many components, including B cells that make antibodies and T cells that can react to infected cells, and a reduction in one does not mean that the vaccines will not offer protection.

“接种疫苗的人应该关注疾病预防控制中心指导的变化, and continue with coronavirus safety precautions to reduce the risk of infection, such as mask-wearing, physical distancing and hand hygiene.”

“We deal with mutations every year for flu virus, and will keep an eye on this coronavirus and track it,” says Bollinger. “If there would ever be a major mutation, the vaccine development process can accommodate changes, if necessary,” he explains.

The Omicron Variant

In November 2021, a variant of the SARS-CoV-2 coronavirus emerged and was named omicron by the WHO, which lists it as a variant of concern. Cases of the highly contagious variant, including a subvariant called BA.2, or “stealth omicron,” 导致COVID-19激增，特别是在安全预防措施放松的地区.

马拉加基斯说:“基因组变体是自2019年以来最大的激增的原因。.

“Omicron has a large number of mutations that all appeared at once. It’s very different from previous versions, including delta. It has over 50 mutations, many in the spike protein, which is how it gets into our cells in the first place. 刺突蛋白也是我们的免疫系统识别的病毒最突出的外部特征之一, responds to and uses to develop antibodies.

“Unfortunately, 组粒是一场完美的风暴:突变使它能够逃避弱免疫反应，并变得更容易在人与人之间传播.

Omicron and BA.2: Do they cause more severe illness?

Bollinger says, “The answer appears to be no. 事实上，有证据表明，组粒基因引起的疾病可能没有丁型变异严重.”

“我们看到的是，组粒可能对我们的上呼吸道比对我们的下呼吸道更有亲和力, and can be more easily spread through talking, coughing or breathing, especially from people without masks on. Omicron also may have more potential for airborne aerosolization of the virus, hanging in the air in indoor settings,” Maragakis says.

Are omicron and BA.2 more contagious than other variants of the coronavirus?

Omicron and especially its subvariant, BA.2, are very contagious, more so than the original coronavirus or the delta variant.

Do the COVID vaccines work on the omicron variant and BA.2?

数据显示，及时接种疫苗和增强剂可以使大多数人免受COVID-19最严重的影响. “充分接种疫苗并在符合条件的情况下尽快接种加强疫苗，可以很好地防止住院和死亡,” says Bollinger.

Current data indicates that even if you are exposed to omicron or BA.2, 及时接种COVID-19疫苗和增强剂将保护您并预防严重疾病.

According to the CDC, research from January 2022 shows that coronavirus vaccine boosters are effective in preventing severe COVID-19. The CDC encourages boosters for those who are eligible, and recommends staying up to date on all COVID-19 vaccines.

“During both Delta- and Omicron-predominant periods, 接种第三剂疫苗在预防与covid -19相关的急诊和紧急护理遭遇方面非常有效(94%和82%), respectively) and preventing COVID-19–associated hospitalizations (94% and 90%, respectively).”

A March 2022 study from the CDC 发现接种两剂或三剂mRNA COVID-19疫苗与COVID-19相关的有创机械通气或死亡风险降低90%相关. 三剂mRNA疫苗在组粒优势期的保护率为94%.

Could a new coronavirus variant affect children more frequently than earlier strains?

雷说，三角洲和组粒变异的广泛感染导致儿童病例数量增加, including uncommon severe infections and deaths.

“没有令人信服的证据表明，任何一种变异都有感染儿童或导致儿童疾病的特殊倾向. 我们需要对这种变化保持警惕，但目前我们只能推测。.

Will there be more new coronavirus variants?

Yes. As long as the coronavirus spreads through the population, mutations will continue to happen, and the delta and omicron variant families continue to evolve.

“New variants of the SARS-CoV-2 virus are detected every week,” Ray says. “Most come and go — some persist, but don’t become more common; some increase in the population for a while, and then fizzle out. When a change in the infection pattern first pops up, it can be very hard to tell what’s driving the trend — changes to the virus, or changes in human behavior. 令人担忧的是，刺突蛋白的类似变化正在多个大陆独立出现.”

Regarding coronavirus variants, how concerned should we be?

“我们在这种病毒中看到的大多数基因变化就像人们一生中积累的伤疤——道路上偶然的痕迹, most of which have no great significance or functional role,” Ray says. “当有足够的证据表明病毒基因变化导致病毒行为发生变化时, we gain new insight regarding how this virus works. 这种病毒在进化过程中似乎有一些局限性——有利的突变是从相对有限的菜单中提取出来的——所以我们有一些希望，我们可能不会看到完全逃脱我们疫苗的变异.

“Updated versions of the current vaccines are being evaluated, 但目前还没有临床试验证据表明，变异特异性疫苗能提供更大的保护. 尽管SARS-CoV-2正在逐渐变化，但它的基因多样性仍然远不如流感.”

“就这些变体而言，我们不需要反应过度，”博林格说. “But, as with any virus, changes are something to be watched, to ensure that testing, treatment and vaccines are still effective. 随着这种冠状病毒的进化，科学家们将继续研究新版本的基因测序.”

COVID Variants: Safety precautions still work

“In the meantime, we need to continue all of our efforts to prevent viral transmission, by practicing safety precautions, 尽快为尽可能多的人接种疫苗，并鼓励在符合条件的人中加强接种,” says Bollinger.

Ray concurs. “Vaccines and boosters are the medical miracle of 2020, but we also need to reemphasize basic public health measures. We have tools at hand 这使个人能够管理风险，包括佩戴高质量的口罩或呼吸器. 等级为FFP2或FFP3的口罩比布制口罩的防护性更强，而且通常更容易佩戴. Hand-washing and avoiding large indoor gatherings, especially with unmasked people, are other ways to mitigate the risk of infection.”

马拉加基斯说:“基本措施有效，每个人都应该意识到，现在任何人都可能感染这种病毒. If you get yourself into that mindset and act accordingly, then if you get that call that someone you know is positive, if you’ve been vigilant, you can know you’re safer.”

She adds, “It’s entirely possible that yet another variant could emerge. 几个月后，免疫力似乎会下降，但助推剂能显著提高免疫力. I encourage everyone who is eligible to get their booster. We are all in this together.”

“新的变种提醒我们，为了我们自己和我们关心的人的安全，我们应该使用多种工具,” agrees Ray.