When the action movie Wolf Warrior II broke China’ s box-office records in 2017, a less prominent (突出的) figure unexpectedly left a strong impression     1     the audience—a military scientist     2     (call) Dr. Chen who developed a vaccine for a deadly virus spreading across Africa.

Two years ago, a real military scientist Dr. Chen Wei     3     (send) from China to Africa to fight against the deadly Ebola. The only difference between the two figures is     4     the real Dr. Chen is “she”.

When SARS broke out in China in 2003, Dr. Chen and her team isolated (隔离) the virus and identified (确认) the cause of the disease without delay.     5     (lucky), the efforts devoted by them had prevented about 14,000 front-line medical workers from     6     (get) infected.

After SARS, the forward-looking woman shifted her attention to Ebola which claimed (夺去生命) over 10,000     7     (life) worldwide. In 2015, she and her team went to Sierra Leone and started their second phase of clinical experiments (临床实验). After countless trials and errors, her vaccine has proven safe and     8     (effect), and been widely administered (供给) to staff assigned to help people in Africa.

From SARS and Ebola to COVID-19, Dr. Chen has spent half of her life fighting against life-threatening viruses.“ We do not have any other choices but     9     (win),” she said. And she made     10    .

3 . Vaccination（接种疫苗）is among the most effective ways to help us prevent diseases. For viruses that don't change too much-the measles virus（麻疹病毒）, for example—getting vaccinated is a once-and-for-all method to prevent you from becoming infected with the virus. If you had two measles vaccines when you were a child, you will be protected for life.

However, it's a different story when it comes to influenza（流行性感冒）, commonly known as "the flu", which generally peaks between December and February. Flu vaccines cannot protect us in the long term.

There is no long-term immunity（免疫）, according to Theodore Strange, associate medical director at Staten Island University Hospital in New York. "The virus essentially 'changes its coat'—HIN1, H2N3, and so on," he told the website Healthline.

Apart from a person's immune protection from flu vaccination declining over time, flu viruses are also constantly changing. So the vaccines are likely to be updated from one season to the next to protect against the viruses that research suggests may be the most common during the upcoming flu season.

Thus, to develop effective flu vaccines, over 100 national influenza centers around the world conduct year-round surveillance（监测）for influenza. Researchers will test thousands of influenza virus samples from patients, according to the official website of the US Centers for Disease Control and Prevention（CDC）. The World Health Organization also suggests there are three or four influenza viruses that are most likely to spread among people during the upcoming flu season.

But even when a vaccine is developed, getting it can prove to be difficult, as it is in high demand and short supply. The timing of influenza vaccine production and distribution is unpredictable, thus the availability of the flu vaccine supply does not always coincide with（与……一致）peak demand.

So scientists prioritize（划分优先顺序）access to the vaccination. The CDC recommends key populations, such as medical staff, teachers, students, children and those aged 60 and above, receive flu vaccines.

This year the situation seems more complicated, as the upcoming flu season coincides with the COVID-19 pandemic. This could overwhelm hospitals, straining（过度使用）resources and healthcare workers' time.