The thing about immunity


In times of the coronavirus pandemic, everyone is talking about immunity. Especially about the concept of “herd immunity” - a hypothetical point in the future, when 60% of the entire population is either infected or already recovered, so the pandemic will come to a standstill. From time to time we even hear stories about people who got infected on purpose, hoping to get over with it as quickly as possible. But also due to the feeling of uncertainty about the virus, many people ask themselves if they can get infected a second time after the recovery.

But what do the scientists have to say about it? And how can we find out whether the cured are immune or not?

First of all, immunity means that the blood contains antibodies against a specific illness. These are usually already created when a person is still sick, so they can help to kill the germs. After recovery, the number of antibodies decreases bit by bit, until they’re finally all gone. Are there only a few antibodies left, they still can defeat a reinfection quickly (and the course will be much more mild), although they cannot fully prevent it. This is called partial immunity.

How about the coronavirus?

To put it in a nutshell: There is not enough data. As it is a novel disease, research started only recently. But recent experiments with rhesus monkey can raise hope. This species is very similar to humans in their reaction to various diseases. Scientists have infected a few monkeys with the coronavirus, they also showed typical symptoms known from humans. After they recovered, the scientists once again infected them with the same pathogen. This time, they didn’t fall sick or showed any symptoms. Although the results should be taken with a pinch of salt, this evidence suggests that an immunity is at least possible.

Now, there are several reports about people who have been tested positive after recovery. Some scientists blame the testing method: With some diseases, there is still detectable genetic material left even months after a full recovery. COVID-19 can indeed be one of them.

A possible scenario: Either shortly before or after recovery, a coronavirus patient gets infected with another virus that shows similar symptoms (like a flu or the common cold). There are the same symptoms again, only caused by another pathogen. At the same time, there is still genetic material of the coronavirus left in the blood. So, tests that are explicitly searching for coronaviruses will deliver a positive result.

Many questions - almost no data

It is still unclear, how long such an immunity can protect someone. Some scientists speculate about a time period of 1-2 years. But these numbers are taken from experience with other coronaviruses and therefore are only partly conclusive.

Is it possible that the body does, in fact, produce antibodies, but they aren’t effective enough to defeat the coronavirus? According to scientists, this would be highly unlikely, but possible. It is also still unclear how the virus will behave in the future. For the moment, scientists assume the virus to mutate surprisingly slowly, which makes immunity easier. Nevertheless, no long-term prognosis can be made. Let’s, for example, not forget that the virus has already split into two strains in the first months of the outbreak.

But there’s always (at least) one glimmer of hope left: The science works hardly and with big financial investitions to produce a vaccine. In order for a vaccine to be effective, the question of immunity should be solved. As the two tasks are intertwined, it is highly likely that we will get more answers very soon.