Most people with covid-19 are still infectious after five days

There is a person by the name ofClare Wilson.

The most comprehensive study yet of people catching covid-19 in real life shows that two-thirds of them are still infectious five days after their symptoms start.

When people are in the first days of developing covid-19, the tests give incorrect results about a third of the time, but they are much more accurate when people stop being infectious.

Seran Hakki and her colleagues studied people before and after covid-19 developed. They asked those who had been in close contact with known cases to carry out frequent nose and throat swabs.

The person's "viral load", which is seen as a key measure of infectiousness, was calculated by using a further test that measured how much infectious virus was in the mucus and how much was in the saliva. The mucus was put in a dish with cells that were vulnerable to infections.

42 people had the beginning and end of their infectious periods revealed by the tests. Hakki says they captured the moment they became infectious.

One in five of these people were found to be infectious before symptoms began. 67 percent of the time, the test gave a positive result. Hakki says that negative results shouldn't be trusted if someone has symptoms.

The majority of people were still infectious five days after their symptoms began. After seven days, 25% were infectious. 92 percent of people who were infectious were found to have positive results from the lateral flow tests.

Although most people can stop self-isolating after five days, they should not meet people who are more vulnerable. For three days, those under 18 are advised to self-isolated.

"This shows beyond a shadow of a doubt that people are releasing infectious virus for far longer than is stated on current guidance," says Stephen, who wasn't involved in the study.

The results may be different for the BA.5 omicron variant. When people in the UK were being exposed to the original coronaviruses strain, the study was done. Omicron is linked with lower viral loads.

Asking people to stay away from work and school would stop the transmission of covid-19, but it would also cause people to stay away from work and school. He thinks five days is a good trade-off.

The guidance is being reviewed by the UK health security agency. Most transmission in adults occurs three days before the start of symptoms to five days after, and the infectiousness for omicron peaks within a shorter time frame than previous versions.

The journal's title is The Lancet Respiratory Medicine.