How many people need to be vaccinated for COVID-19 herd immunity?
The current global situation of the COVID-19 epidemic is still severe, and the anti-epidemic pressures vary from place to place. Non-pharmaceutical interventions (wearing masks, washing hands frequently, maintaining safe social distancing, etc.) have played a very important role in epidemic prevention and control, but they really need to be overcome. The epidemic still depends on improving herd immunity. COVID-19 vaccination is the fastest and most effective way to improve herd immunity.
The basic characteristics of the WHO ideal vaccine have four points:
1. The safety assessment is excellent and it is suitable for many types of people, such as the elderly, children and pregnant women.
2. No contraindications and very few adverse reactions.
3. Theoretically, it will take effect within at least two weeks, and the effective rate will reach 70% and above.
4. The protection period of the vaccine is at least one year.
From the vaccination rate to the realization of herd immunity, this is a topic that cannot be avoided by public health. Therefore, based on the basic reproduction number R0 of the COVID-19 and the effective rate of the vaccine, the theoretical inoculation rate of the COVID-19 vaccine is estimated. “If the basic reproductive number (R0) of the global COVID-19 is 2.66, then the theoretical vaccination rate of the global vaccine is 89.2%. Specifically, the basic reproductive number (R0) of the COVID-19 in Asia is 2.28. According to the WHO proposal, the vaccine should be 70%. The theoretical inoculation rate is 82.7%. The basic reproduction number (R0) of the COVID-19 in Europe is 3.06, and its theoretical inoculation rate is 96.2%.”
For some countries, in order to form herd immunity, the theoretical scale of inoculation of the COVID-19 vaccine is also different. “The basic reproductive number (R0) of the COVID-19 in China is 2.40, the vaccination rate is 83.3%, and the scale of vaccination is 1,199.4 million; the basic reproductive number (R0) of the COVID-19 in India is 1.62, and the vaccination rate is 54.7%. The scale of vaccination is 754.4 million.” Professionals believe, “Obviously, to achieve this scale of vaccination, the global vaccination task is very difficult.”
