Study finds coronavirus infection after exposure faster than expected – POLITICO Europe

Exposing people to a tiny amount of coronavirus led to infection on average 42 hours later, according to preliminary results from the first British study testing participants response to the virus.

A study of 36 highly screened healthy people who had volunteered to be infected with the virus, found that in the 18 people who became COVID-19 positive (defined as two positive PCR tests), the time between exposure and viral detection was significantly shorter than existing estimates putting the average incubation period at five to six days.

The study found that the smallest planned dose of the virus administered up the nose was enough to infect half of the participants, aged between 18 and 30, so no higher doses were tested.

Once infection was detected, there was a steep rise first in the amount of virus found in the throat, followed by the nose, where virus levels were the highest.

Virus levels peaked at around five days, but high viral load was still picked up in lab tests up to 12 days later for some. There were no severe symptoms or clinical concerns, with mild symptoms ranging from sore throat to aches and pains, and headache.

While this human challenge study used a virus isolated early in the pandemic, the researchers are planning a next study using a Delta strain, most likely in vaccinated volunteers.

The researchers told journalists they intend to begin the study in spring and expect it to contribute to data on the new COVID-19 vaccines and antivirals.

Wednesday's study, a collaboration between Imperial College London, the Royal Free London NHS Foundation Trust, hVIVO, the Vaccine Task Force and the Department of Health and Social Care, is available online but has not yet been peer reviewed.

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Study finds coronavirus infection after exposure faster than expected - POLITICO Europe