New research, called challenge study on covid, from the UK shows how fast Covid infection spreads and takes hold of the body

World-beating challenge research on Covid was conducted by British experts. So, what exactly is the challenge of the study?

It enables doctors to monitor healthy people who have Covid for the duration of the infection, which is not possible with Covid patients.

Incubation Period During Delta Variant

On average, symptoms showed up in newly infected people about five days after contact.

In some instances, symptoms appeared as quickly as two days after exposure, but most people with symptoms would have them by Day 12.

The other sick people investigated were clearly ill by the time Day 14 came around.

In some very rare cases, symptoms can show up after 14 days, with researchers estimating this happens with about one in every 100 people.

Incubation Period During Omicron variant

Given the possibility of a shortened incubation period, according to experts, anyone who has contact with an infected individual gets tested about 72 hours after the exposure.

Coronavirus Incubation Period at current scenerio

The current study followed 36 healthy young adults who had no immunity to the coronavirus.

Participants aged 18 to 30 years old who had never been vaccinated against Covid-19 and had never been infected with the disease were given a low dose of the virus – delivered by drops up the nose – and then observed in a controlled environment for two weeks.

They were given the smallest amount of virus that may induce infection, around the same as what would be detected in a single droplet of nose fluid when someone was at their most contagious.

Imperial College London, the Vaccine Taskforce, the Department of Health and Social Care, and the Royal Free Hospital in London collaborate on the Human Challenge Programme.

The key findings revealed that symptoms appear relatively quickly, on average two days following an encounter with the virus.

The infection begins in the throat and peaks after five days, by which time it has become substantially more ­abundant in the nose.

This groundbreaking study conducted at the Royal Free Hospital demonstrated that experimental infection of volunteers accurately mimics real infections, paving the way for future challenge tests of novel vaccines and treatments against Covid-19.

The average time from first exposure to the virus to viral identification and early symptoms (incubation period) was 42 hours among the 18 infected participants, much less than previous predictions of five to six days.

Following this time, the amount of virus (viral load) identified in swabs taken from participants’ noses or throats increased dramatically, culminating at roughly five days.

There were some differences in the locations where the most virus was discovered. The virus was discovered in the throat first, much before it was discovered in the nose (40 hours in the throat compared to 58 hours in the nose).

In addition, peak viral levels in the nose were substantially higher than in the throat.

This suggests that the danger of viral transmission from the nose is higher than from the mouth, emphasizing the need of wearing a face mask that covers both of these locations.

“This important study has provided further key data on Covid-19 and how it spreads, which is invaluable in learning more about this novel virus, so we can fine-tune our response,” says Professor Jonathan Van-Tam, former deputy chief medical officer, adding “Challenge studies could still prove to be important in the future to speed the development of ‘next-generation’ Covid-19 vaccines and antiviral drugs.”

”Image Credit: Getty

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