A vaccine for coronavirus could be at least a year away,but the government seems to be trying to engineer the same effect with something called herd immunity.
The expectation is that enough people will become infected with the virus that they develop immunity, this would stop it spreading widely and protect the vulnerable.
Here's an example.
We know that each person who catches the virus is likely to pass it to between 2.4 and three others, but if enough people develop immunity, then transmission is reduced considerably because there are fewer susceptible people.
But how many is enough depends on how contagious the disease is.
As this chart shows, measles is very infectious, one person can pass it on to twelve others and so for herd immunity to work, around 90% need to be immune.
But coronavirus reproduces at a far slower rate, so successful containment requires just 60% of people to have been infected and develop resistance.
Now taking the UK as a whole, that's around 40 million people catching Covid-19. The available evidence suggests 32 million or 80% of them would have mild symptoms, but that means around 8 million we could have severe or critical symptoms and would need treatment in hospital.
The government expects 50% of those severe cases to be in hospital during the peak of the outbreak, which is expected to last around 3 weeks, and that would put considerable strain on the NHS.
But of course that assumes you haven't isolated the most vulnerable people and that could be crucial.
Each death is a death too much and each person who has to be admitted in intensive care occupies a bed, that may be essential to save lives for someone who has a stroke or heart failure or what have you, so I don't think we can let nature go, you know, it's game.
Scientists also have no idea how long it would take for 60% of the population to become infected, that number simply hasn't been reached in any other country.
單詞釋義：
herd immunity : 群體免疫
herd /hɜːd/ n. 獸群，畜群；放牧人 (文中則側重於群體的概念，不要僅僅局限於詞典的解釋，因為很多時候，詞典並不能涵蓋單詞在實際使用中所有的意思和一些引申用法。所以要避免死記硬背，更多地通過閱讀等去感受單詞的用法和意思)
immunity /ɪ'mjuːnɪtɪ/ n.免疫力
vaccine /'væksiːn/ n. 疫苗;痘苗
coronavirus /kəˈrəʊ.nəˌvaɪə.rəs/ n.冠狀病毒
engineer /endʒɪ'nɪə/ vt. 策劃；設計；精明地處理
effect /ɪ'fekt/ n. 效果；作用；影響
vulnerable /'vʌln(ə)rəb(ə)l/ adj. 易受傷的, 脆弱的, 敏感的
transmission /trænz'mɪʃ(ə)n/ n. 傳送, 傳播, 傳達
considerably /kənˈsɪdərəblɪ/ adv. 相當,非常,頗
susceptible /sə'septəb(ə)l/ adj. 易受影響的; 易動感情的
contagious /kən'teɪdʒəs/ adj. (病)有傳染性的
chart /tʃɑːt/ n. 圖表
measles /'miːz(ə)lz/ n. 麻疹；風疹
immune /i'mju:n/ adj. 免疫的, 有免疫力的; 不受影響的
reproduce /riːprə'djuːs/ vt. & vi. 複製; 重現; 再版；生殖, 繁殖
containment /kən'teɪnm(ə)nt/ n. 控制;抑制
resistance /rɪ'zɪst(ə)ns/ n. 抵抗, 反抗, 抵抗能力
available /ə'veɪləb(ə)l/ adj. 可用的或可得到的
outbreak /'aʊtbreɪk/ n. 爆發, 突然發生
considerable /kən'sɪd(ə)rəb(ə)l/ adj. 相當大(或多)的
strain /streɪn/ n. 壓力
NHS：National Health Service 英國國家醫療服務體系
assume /ə'sjuːm/ vt. 假定
isolate /'aɪsəleɪt/ vt. 使孤立；使絕緣；使隔離
crucial /'kruːʃ(ə)l/ adj. 決定性的；重要的；定局的；決斷的
admit /əd'mɪt/ vt. & vi. 許可進入
intensive /ɪn'tensɪv/ adj. 加強的, 集中的, 密集的
stroke /strəʊk/ n.中風