What is herd immunity
That’s what they call it state any community in which a large number of people have immunity to any infectious disease. It allows you to minimize the risks of spreading viruses, bacteria or other pathogens transmitted from person to person, and, accordingly, reduce the likelihood of disease outbreaks or epidemics. However, it may not appear for all infections. For example, due to the mutation rate for influenza and coronavirus, it is unattainable.
How does herd immunity work?
Immunity occurs when antibodies appear – specific proteins in the blood plasma that the immune system produces specifically to fight infections. Once encountering a virus or bacteria, the body will remember it and will know what to do if it encounters it again. As a result, if the infection enters the body again, the immune system will quickly destroy it.
For herd immunity to occur, 100% of the population does not have to have it. The indicator can vary between 40–95%. Exact numbers depend on the infection contagiousness index. This value shows how many people out of 100 can become infected after contact with a sick person. For example, in measles it high — 95%, respectively, for collective immunity to occur, at least 95% of people need to have antibodies. U polio the index is slightly lower – 80%, and flu – 60%.
The main goal of herd immunity is to reduce the likelihood of a collision between a sick person and a person susceptible to the disease. Imagine a room in which there are 100 people: 95 of them have immunity, four without it stand at the edges, and in the center is the only patient. People who separate the “infectious” and the “unprotected” literally create a shield that prevents the infection from spreading. Of course, if everyone in the room suddenly starts changing places, there is a chance that the patient will cross paths with a person from the risk zone, but it is small. And if you scale this example to the size of a city, region or country, the risks will become even smaller.
How is herd immunity formed?
![What is herd immunity and how does it save even those who are against vaccines so far? What is herd immunity and how does it save even those who are against vaccines?](https://cdn.lifehacker.ru/wp-content/uploads/2024/05/immunitet-2_1716282616-630x315.png)
There are really only two ways to achieve this.
Living with illness
A large percentage of the population must survive the infection and recover. For example, in 1918 it was like this formed herd immunity from the Spanish flu.
This method There is several controversial points. Firstly, it is dangerous: there is no guarantee that the disease will not cause any significant health complications and will not lead to death. Secondly, such formation of collective immunity does not provide complete confidence that the disease will never recur. You don’t need to look far for an example – during the coronavirus pandemic, some people got sick again
Vaccination
That is introduction into the body of killed or weakened forms of the pathogen – the immune system will also respond to them by producing antibodies, while you will not have to experience the symptoms of the disease and deal with possible complications from it. For example, this is how collective immunity to polio.
Vaccination is considered a more effective way. It can be one-time, periodic or regular – it depends on the characteristics of the disease, in particular the period for which immunity from it remains in the body.
It should be borne in mind that vaccination does not provide a 100% guarantee of protection. Let’s say the measles vaccine reducesthe risk of getting sick is approximately 97%. Therefore, there is no need to forget about precautionary measures like regular hand washing.
Vaccines against dangerous infections, to which it is better to have collective immunity in society, are included in the national calendar of preventive vaccinations (NCPP). In Russia, such relate, for example, viral hepatitis B, tuberculosis, diphtheria, whooping cough, tetanus, polio, measles, rubella. If you get vaccinated against them on time, that is, according to the NKPP schedule, then you can do it for free at the hospital at your place of residence. Vaccines in Russia now trains holding “Nacimbio” for the full cycle – from antigen production to drug formation.
Why is herd immunity necessary?
![What is herd immunity and how does it save even those who are against vaccines? What is herd immunity and how does it save even those who are against vaccines?](https://cdn.lifehacker.ru/wp-content/uploads/2024/05/immunitet-1_1716282668-630x315.png)
Firstly, it reduces your own risks of encountering the disease, but there is also a more global reason. Some groups of people literally depend on herd immunity because for some reason they cannot get vaccinated themselves. To them relate:
- people with weakened immune systems, including white blood cell abnormalities, a removed spleen, or HIV;
- people who are undergoing radiation or chemotherapy;
- babies;
- elderly.
Herd immunity also protects people who deliberately refuse vaccination without objective reasons. But up to a certain point, if there are too many anti-vaxxers, problems can arise. For example, in 2019 worldwide happenedMassive outbreaks of measles: WHO recorded as many as 120 cases per million people (for comparison: in 2016 there were only 18 per million). This is partly due to the lack of vaccinated people. The measles vaccine is given in two doses – one year and one at 6 years: according to as of 2019, about 85% of children had the first, and only 71% had the second. Let us remind you that for collective immunity against measles, at least 95% must be covered.
After such a sharp jump, the situation was stabilized, but not completely – outbreaks of measles are still occurring. And in Russia in 2023 the situation is even worsened— the incidence increased 127 times compared to 2022, 8.92 cases per 100 thousand people were registered. This is the highest figure in 30 years – in 1994 there were about 20 cases per 100 thousand people. Mistrust of vaccinations also played a role here: a survey among the country’s doctors in 2023 showed that more than a quarter of parents refuse from the measles vaccine.