In my past post "herd immunity as a public good", I have explained that vaccination that generates herd immunity is a public good and so economists can analyze the problem, using the theory of public goods. At that time (September 2020), vaccination is a remote issue. Now, the issue is no longer remote. UK and US have approved some vaccines for Covid-19 to be used for common citizens in these countries. Certain problems in relation to herd immunity has also become clear. Let us discuss.
Recall what is the issue. First, vaccination can prevent widespread infections of a disease. If many people have already taken vaccines, they are immune to an infectious disease. The disease cannot be easily spread in such a society (but it cannot definitely prevent the spread). This is a public good, which is non-rivalrous and non-excludable. A good is non-rivalrous if someone's taking it will NOT diminish its availability for others (such as streetlights). A good is non-excludable if there is no (easy) way to prevent one from taking or enjoying it (like fresh air) within a scope (say, in a city) when the good is already there. Now, herd immunity is both non-rivalrous and non-excludable. If most people are immune to the disease already, it is not easy for you to get infected. Your low risk of being infected will not make others more risky. Others still can enjoy the low infection risk. Also, you cannot prevent others from enjoying this low risk.
In my past post, I have mentioned that the idea is not free of controversy. Some people (including influential people) believe that vaccination is unnatural, will cause severe side-effects, and does more harms than benefits. At that time, this is only an abstract idea for Covid-19 vaccines. But now, things become more concrete as the first groups of vaccinated citizens appeared and the side-effects are widely reported. Furthermore, soon we also need to assess if and when we should be vaccinated.
Recall what is the issue. First, vaccination can prevent widespread infections of a disease. If many people have already taken vaccines, they are immune to an infectious disease. The disease cannot be easily spread in such a society (but it cannot definitely prevent the spread). This is a public good, which is non-rivalrous and non-excludable. A good is non-rivalrous if someone's taking it will NOT diminish its availability for others (such as streetlights). A good is non-excludable if there is no (easy) way to prevent one from taking or enjoying it (like fresh air) within a scope (say, in a city) when the good is already there. Now, herd immunity is both non-rivalrous and non-excludable. If most people are immune to the disease already, it is not easy for you to get infected. Your low risk of being infected will not make others more risky. Others still can enjoy the low infection risk. Also, you cannot prevent others from enjoying this low risk.
In my past post, I have mentioned that the idea is not free of controversy. Some people (including influential people) believe that vaccination is unnatural, will cause severe side-effects, and does more harms than benefits. At that time, this is only an abstract idea for Covid-19 vaccines. But now, things become more concrete as the first groups of vaccinated citizens appeared and the side-effects are widely reported. Furthermore, soon we also need to assess if and when we should be vaccinated.
Recent news reports say that, to attain herd immunity, about 75% of people are required to be vaccinated. But surveys show that only 60% of the people in the US are willing to be vaccinated. Hence, even though vaccines are there, US cannot be rescued from the pandemic if vaccination is purely voluntary! In fact, certain people are not suitable for taking vaccines as they suffer from allergic problem. They can only wait for others to take vaccines, establishing herd immunity so that they will also be safe. But if not sufficient people take vaccines, they cannot be protected in this way. Herd immunity is not only about protecting oneself (those who have taken vaccines) but also for protecting the minority (who are not suitable for vaccines).
My past post has already mentioned that voluntary contribution to the public good is less likely in the case of herd community. From recent news reports, we know this is not only a possible situation, but is real. What economists will say then? In economics, normally tax/subsidy or public provision will be recommended for public goods (if voluntary contribution is not likely). In the case of herd immunity (as a public good), the problem may not be simply financial cost (so that a subsidy can reduce the cost of taking vaccines). The one who does not want vaccines may either believe that vaccines are bad for health or they are allergic or unsuitable for vaccines. Giving them some money may not change their minds. For the latter type (allergic), we also should not change their minds. Then, should we consider compulsory vaccinations (public provision of herd immunity)? I doubt this option will be seriously considered at all, especially in places like US.
So, people are trapped in the problem that voluntary (non-compulsory) contribution to a public good leads to insufficient provision of the good, and we don't see an easy way out!
However, I am not that pessimistic. The point is, people will change their mind. When someone see others who have taken vaccines and do not suffer from a big problem, they may also take vaccines, especially when Covid-19 is such an important death-or-alive issue, and receives so many attentions than any other types of vaccines. However, how to promote the issue and how to convey the messages (that vaccination is not unhealthy) is a key point, and no governments should take it lightly.
