How long am I contagious with a corona infection? A British study got to the bottom of the question and has now published the latest findings.
It is probably a question that not only concerns those affected: How long and from when is a corona infected person contagious? Researchers at Imperial College London now have new detailed insights into how long sick people should isolate themselves.
Only when the symptoms appear is it actually contagious
The study team conducted detailed daily tests from the point at which 57 people were exposed to SARS-CoV-2 to examine when and for how long people were contagious. Contrary to the widespread assumption, it was shown that infected people can only infect others when the first symptoms appear. Study leader Prof. Ajit Lalvani explains in a university statement: “We closely monitored people and recorded when they developed an infection until they stopped being contagious. This enabled us to precisely define the respective time windows. This is fundamental to combating any pandemic.”1 And he adds: “There remains a lack of clarity about how to safely emerge from self-isolation. Our study is the first to assess how long infectivity lasts, using real-life evidence.”
Also interesting: That’s how likely it is that you Corona had without noticing it
Study with 57 infected people
The 57 participants who were confirmed to be infected filled out daily questionnaires about their symptoms and took nose and throat swabs, which were sent to a laboratory for PCR testing. PCR positive samples were then tested to determine how infectious the virus actually was. In addition, the subjects carried out a total of 652 quick tests on themselves. Incidentally, three of them had no symptoms despite positive tests. The results can currently be read in the journal «The Lancet Respiratory Medicine».2
Also interesting: Experts concerned about the new corona variant BA.2.75
How long people infected with corona are really contagious
In a nutshell, the study found that infected people are usually only contagious for five days, and only after they have developed symptoms. However, it can occasionally happen that they are already infectious before they appear. Therefore, one should never feel safe. The corona pandemic teaches us: very, very many exceptions confirm the rule! The study also revealed that it can happen that you are still contagious even after the five days have passed. But one thing is certain: the infectiousness decreases more and more with each passing day.
Also interesting: Boosted are less contagious with omicron infection
Quick tests provide reliable information
For Lalvani and his team, the common rapid antigen tests provide comparatively reliable information on whether and how long you are still contagious with Corona. Based on their results, the researchers recommend that people with corona should isolate themselves for five days and then carry out rapid tests from the sixth day. If the tests are negative two days in a row, it is safe to leave isolation.
Also interesting: Omikron BA.5 – this is how the symptoms differ from previous corona variants
Does the study also apply to Omikron?
The investigation took place between September 2020 and March 2021. At that time, alpha and delta were the dominant variants. Omicron was still in the stars. Are the results still transferrable? Yes, emphasize the study authors: “There is even evidence that omicron variants have a lower viral load and are therefore probably contagious for a shorter period of time.” This could mean that those currently infected are probably contagious for less than five days on average. As Corona is so unpredictable – as mentioned before – scientists are extremely cautious with clear recommendations regarding omicron and duration of contagion.