COVID-19 Vaccines Might Be Changed to Fight New Versions of Virus

The makers¹ of coronavirus vaccines² are learning how to change their vaccines to deal with virus mutations. Experts are looking to influenza⁵, or flu, vaccines to help them understand if and when the shots may need to be changed.

Richard Webby directs a World Health Organization (WHO) flu center from St. Jude Children's Research Hospital in Virginia. He said that the process will not happen quickly.

"It's not really something you can sort of flip⁶ a switch, do overnight," Webby said.

Viruses mutate, or change, often. Recent studies have raised concerns that first-generation COVID-19 vaccines are not as effective against a coronavirus mutation⁴ that first appeared in South Africa. However, many of the COVID-19 vaccines are made with new technology that permits changes. But it will still be difficult for experts to decide whether the virus has mutated enough to make it necessary to change the vaccines.

Flu offers a model

The WHO and the U.S. Food and Drug Administration (FDA) are looking to the worldwide flu vaccine³ system for help. Influenza mutates much faster than the coronavirus. Flu shots have to be changed nearly every year.

National centers around the world collect spreading flu viruses and observe how they change over time. They send samples to special WHO laboratories for high-level "antigenic" testing to decide on vaccine strength. WHO experts and government rule-makers work together to agree on each year's new vaccine recipe. Manufacturers then make the necessary changes.

For COVID-19 vaccines, Webby said an important step will be establishing a similar observation and testing network. It can then decide on which mutations are most worrisome. Today, there are wide differences in how nations track and test mutated versions. For example, Britain does more testing of the changing viral genome than the United States does.

Three variants⁸ first discovered in Britain, South Africa and Brazil are worrisome because of combinations of mutations that make them spread more easily and quickly.

On Sunday, U.S. researchers reported another mutation found in seven variants that have appeared in several U.S. states. Researchers do not yet know if this mutation makes the virus easier to spread.

Current COVID-19 vaccines and variants

Just because a variant⁹ spreads more easily does not mean it will be resistant¹⁰ to a vaccine. But the variant first identified in South Africa is raising concerns.

Columbia University's David Ho put blood samples from people given the Pfizer or Moderna vaccines into small containers with the mutated virus. He found that vaccine-produced antibodies still offered protection, but the protection was much less strong.

Early test results of two other vaccine candidates — from Novavax and Johnson & Johnson — supported Ho's findings. Both still offered protection. However, that protection was weaker in South Africa than in other places. A much smaller test of the AstraZeneca vaccine in South Africa has raised questions about its effectiveness.

Several of the approved and available COVID-19 vaccines require two shots for full effectiveness. The drugmaker Moderna is about to explore one possible solution: Could a third shot of its vaccine raise immunity¹¹ enough to fight off some variants?

Ho said it is a good idea to test, because people may "still have plenty of cushion" if their antibody levels are very high.

Changing the recipe

Major manufacturers also are developing experimental variant vaccines as an extra measure.

COVID-19 vaccines produce antibodies that recognize the spike¹² protein that covers the coronavirus. When the virus mutates, sometimes the spike protein is changed in ways that make it harder for vaccine-produced antibodies to recognize.

The Pfizer and Moderna vaccines are made with a piece of genetic¹³ information called messenger RNA (mRNA). It tells the body how to make some harmless copies of the spike protein that train disease-fighting cells. To change the vaccine, the drugmakers can simply change the first version of genetic information with mRNA for the mutated spike protein.

The AstraZeneca vaccine and the one made by Johnson & Johnson are expected to be available in the United States soon. Both are made with cold viruses engineered to introduce a spike protein gene⁷ into the body. Making changes to these two vaccines requires growing cold viruses with the mutated gene. The process is a little more complex than the mRNA process. But it is still not as difficult as remaking traditional flu shots.

Testing vaccines, round two

First-generation COVID-19 vaccines were tested in tens of thousands of people to be sure they work and are safe. The research took many months.

Simply changing the recipe to better target virus mutations will not require repeating those studies in thousands of people, said Dr. Peter Marks. He is the vaccine chief with the FDA. He recently told the American Medical Association that the FDA plans to be "pretty nimble" when it comes to approving vaccine changes. In other words, it will act quickly.

If an updated vaccine is needed, he said, tests in a few hundred people would likely be enough to know if it causes a good immune reaction.

Words in This Story

mutation –n. a change in the genes¹⁴ of a plant or animal that causes a different quality to be recognized

flip a switch –idiom to easily and quickly make a change

sample –n. a small amount of something that is used to give information about what it was taken from

recipe –n. a set of directions for making food

track –v. to follow and observe, especially in an effort to find evidence

genome –n. the total amount of genetic information in the chromosomes¹⁵ of an organism

variant –n. something that is different in some way from others of the same kind

cushion –n. something extra that can reduce bad effects or problems

spike –n. a sharp, thin structure that sticks out from something

1 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

2 vaccines   

疫苗，痘苗( vaccine的名词复数 )

参考例句：

• His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
• The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

3 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

4 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

5 influenza   

n.流行性感冒，流感

参考例句：

• They took steps to prevent the spread of influenza.他们采取措施
• Influenza is an infectious disease.流感是一种传染病。

6 flip   

vt.快速翻动；轻抛；轻拍；n.轻抛；adj.轻浮的

参考例句：

• I had a quick flip through the book and it looked very interesting.我很快翻阅了一下那本书，看来似乎很有趣。
• Let's flip a coin to see who pays the bill.咱们来抛硬币决定谁付钱。

7 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

8 variants   

n.变体( variant的名词复数 )；变种；变型；（词等的）变体

参考例句：

• Those variants will be preserved in the'struggle for existence". 这些变异将在“生存竞争”中被保留下来。 来自辞典例句
• Like organisms, viruses have variants, generally called strains. 与其他生物一样，病毒也有变种，一般称之为株系。 来自辞典例句

9 variant   

adj.不同的，变异的；n.变体，异体

参考例句：

• We give professional suggestions according to variant tanning stages for each customer.我们针对每位顾客不同的日晒阶段，提供强度适合的晒黑建议。
• In a variant of this approach,the tests are data- driven.这个方法的一个变种，是数据驱动的测试。

10 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。

11 immunity   

n.优惠；免除；豁免，豁免权

参考例句：

• The law gives public schools immunity from taxation.法律免除公立学校的纳税义务。
• He claims diplomatic immunity to avoid being arrested.他要求外交豁免以便避免被捕。

12 spike   

n.长钉，钉鞋；v.以大钉钉牢，使...失效

参考例句：

• The spike pierced the receipts and held them in order.那个钉子穿过那些收据并使之按顺序排列。
• They'll do anything to spike the guns of the opposition.他们会使出各种手段来挫败对手。

13 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

14 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

15 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》