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When do we achieve COVID 19 herd immunity?
The concept of herd immunity is often mentioned in the discussion about the coronavirus pandemic. What is meant by this is that a sufficient proportion of the population is immune to an infectious disease, making it less likely for individuals to become infected with the disease. When can COVID-19 expect such herd immunity?
Dr. Gregory Poland is an infectious disease expert at the renowned Mayo Clinic in the United States. He heads a vaccine research group looking for a vaccine against COVID-19. In a recent communication from the clinic, he explains the principle of herd immunity and when general protection can be expected in the population.
What is herd immunity?
Dr. Poland uses a simple example to explain herd immunity. When a hundred people interact in a confined space and someone has a new virus, every interaction with the infected carries a risk of infection. In a short time, the virus spreads to other people in the group. These fall ill and develop antibodies against the virus.
The next time you come into contact with an infected person, those who were already ill will no longer fall ill. If the proportion of those recovered is high enough, the risk of infection for those who have not yet come into contact with the virus will also decrease, since it will be less likely to interact with a potential transmitter who will pass on the virus. “The more immune people are around the vulnerable, the less likely the virus can infect someone,” explains Poland. The recovered act like a shield around the vulnerable.
How do you acquire herd immunity?
According to Dr. Poland has two main approaches that can be used to acquire herd immunity. The first way is that as many people as possible get the infection. “In the context of COVID-19, this means that you have to be prepared to accept a lot of serious illnesses and even deaths to get there,” explains the infectious disease expert.
Another strategy is to use a vaccine or antibody therapy to make the body think that it has already been exposed to the virus. This stimulates the immune system to produce its own antibodies against the virus without actually being ill, explains Poland.
Until a suitable therapy is available, only the first way can be followed. Here, however, it is crucial how quickly the infection spreads. If too many people fall ill at once, the health system could collapse, which could have drastic consequences for all illnesses, accidents, births or similar events in which the health system plays an important role.
How many people need to have antibodies?
"We know that around 60 percent of the population must be immune to flu in order to have herd protection," says the professor. Measles must be as high as 95 percent because it is a highly contagious infection. According to the current state of knowledge, around 70 percent of a population in SARS-CoV-2 must have come into contact with the virus, reports Poland.
How long does it take in Germany?
A recent joint statement by the Fraunhofer Institute, the Helmholtz Institute, the Leibnitz Society and the Max Planck Society shows that it would take several years for herd immunity to exist in Germany. To achieve such immunity, restrictive measures would have to be maintained over the entire period so that the health system is not overloaded. (vb)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Graduate editor (FH) Volker Blasek
- Mayo Clinic: Understanding herd immunity (published: May 4th, 2020), newsnetwork.mayoclinic.org
- Joint statement by the Fraunhofer Institute, the Helmholtz Institute, the Leibnitz Society and the Max Planck Society: Strategies to curb the COVID-19 pandemic (published: April 28th, 2020), mpg.de