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Swedish analysis suggests World Health Organization may be underestimating spread of COVID-19 coronavirus

The COVID-19 virus may be at least as transmissible as SARS; WHO officials cautioned it's too early to tell if the spread will keep slowing.

Jeff Lagasse, Associate Editor

Just yesterday, officials from the World Health Organization said the spread of the COVID-19 coronavirus has been slowing down, meaning it likely won't rise to the level of a pandemic as some had feared.

But new research coming out of Sweden suggests the coronavirus probably has a stronger ability to spread than WHO has estimated so far, basing this on a review of previous studies of the coronavirus' transmissibility.

Based on the findings from Sweden's Umeå University, the COVID-19 virus is at least as transmissible as SARS, another coronavirus that caused widespread concern when it began spreading several years ago.


WHO estimates that the coronavirus has a transmissibility, expressed as a reproduction number, of between 1.4 and 2.5. A reproduction number is a measurement of how many people a contaminated person transmits the virus to in a previously healthy population. The higher the number, the more transferable the virus is and the higher the risk for rapid spread. When the reproduction number falls below 1.0, the epidemic is likely to die out.

Researchers carried out a review of several scientific studies of the novel coronavirus, and found twelve studies of sufficiently high quality. The studies consisted of estimations of the growth rate based on cases observed in the Chinese population, and on statistical and mathematical methods.

The earliest studies of the coronavirus indicated a relatively low transmissibility. Thereafter, the transmissibility rose rapidly to stabilise between 2-3 in the most recent studies. The reproduction number summed up to a mean of 3.28 and a median of 2.79, which is significantly higher than WHO's estimation of 1.4-2.5.

Meanwhile, the Centers for Disease Control and Prevention said the novel coronavirus is "not currently spreading in the community in the United States," but that it is an "emerging, rapidly evolving situation."

"For severely ill individuals, testing can be considered when exposure history is equivocal (e.g., uncertain travel or exposure, or no known exposure) and another etiology has not been identified," according to the CDC. The availability of test kits is limited, and "performance issues" were identified in the manufacturing of one of the reagents, so these will need to be replaced.

On social media, people with cough and fever are posting their concerns that hospitals will not test them for COVID-19 even if they are negative for influenza -- which is highly prevalent at the moment, according to Doctors for Disaster Preparedness. One was concerned about touching, but not opening, a package she had received from Wuhan, the virus' epicenter in China.

Virus does remain infective on surfaces for a time, but is destroyed by ultraviolet exposure (as from sunlight) or disinfectants including rubbing alcohol. Chinese banks are disinfecting banknotes by using ultraviolet light or high temperatures, then sealing and storing the cash for 7 to 14 days before recirculating.


WHO Director General Dr. Tedros Adhanom Ghebreyesus said Monday that 72,000 cases have been reported in China, with 1,772 resulting in death. Most of these cases are local to Wuhan. Outside China, 694 cases have been reported around the world.

The latest data shows a decline in new cases of the virus, but Ghebreyesus said this trend should be interpreted cautiously, and added that WHO is unsure whether the decline will continue.

He also said it appears the COVID-19 coronavirus is not as deadly as other relatively recent coronaviruses. About 14% of those affected experience severe cases of pneumonia and shortness of breath; many have septic shock and organ failure, and the risk of death generally increases with age.

Twitter: @JELagasse

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