Virus could be more contagious than thought

The virus t hat causes COVID- 19 could be even more contagious than previously believed, a new study released this week found.

In the early days of the outbreak in China, the number of infected people doubled every 2.3 to 3.3 days as opposed to the six to seven days that was previously believed, the study found.

That means that the initial R number, which is the number of people that an infected person is expected to infect, is also much higher. Most experts had that number pegged at 2.2 to 2.7, but the researchers believe it something closer to 5.7.

The findings were published in an early release article from the Los Alamos National Laboratory and posted on the Centers for Disease Control and Prevention website on Tuesday.

The researchers said the findings illustrate the need for active surveillance of confirmed cases and contact tracing, which means figuring out who they have been in contact with. The researchers also argue for quarantines and early and strong social distancing measures.

The higher level of infectiousness also means that herd immunity will be harder to achieve. With a lower R, such as 2.2, only 55 per cent of the population would have to be infected or vaccinated to achieve herd immunity. With an R of 5.7, that number rises to 82 per cent.

The study also hammers down the trajectory of the disease once a person is infected.

The researchers estimate that the incubation period, or the time it takes to feel symptoms after being infected is 4.2 days, which is consistent with other estimates.

The average amount of time it takes before a person is hospitalized after feeling symptoms varies considerably. Before human- to- human transmissions were being reported in China, it took 5.5 days on average for a person to be hospitalized. After Jan. 18 that number shortened to 1.5 days.

The average time from hospital admittance to discharge was 11.5 days and the average time in hospital before a person died from the disease was 11.2 days. The time from symptom-onset to death was 16.1 days.

During a briefing Thursday, Canadian health officials said they estimated that before stronger public health measures were introduced each infected Canadian infected 2.2 other people on average.

There are a few reasons why the numbers from China in January could be higher. For one, the study estimates that somewhere between 40,000 and 140,000 people in Wuhan travelled outside of Hubei Province before the lockdown was imposed on Jan. 23.

Canadian health officials also had the luxury of several months to prepare as they watched the outbreak sweep across the globe and instituted social distancing measures early on.