A January 14 WHO tweet that has been widely re-broadcast months later by the right-wing US press (e.g. NYPost, WashExam but not exclusively by them, e.g. Bloomberg opinion piece, Politico o.p.) said that:

Preliminary investigations conducted by the Chinese authorities have found no clear evidence of human-to-human transmission of the novel #coronavirus (2019-nCoV) identified in #Wuhan, #China.

The WHO is lampooned for this moment by the aforementioned media pieces, but these don't really say when the WHO came to a different conclusion regarding human-to-human transmission. So when did that happen, and what information source did the WHO use for the latter determination?


2 Answers 2


The WHO was clearly wary that human-to-human transmission may be a factor at the beginning of January - although their initial Disease Outbreak News (DON) of January 5th entitled "Pneumonia of unknown cause – China" states that:

According to the authorities, some patients were operating dealers or vendors in the Huanan Seafood market. Based on the preliminary information from the Chinese investigation team, no evidence of significant human-to-human transmission and no health care worker infections have been reported.

They also note that all patients are being isolated, and that close contacts of patients are being identified and monitored, which indicates that this avenue was being investigated.

Further advice published on 10th January also indicated that:

From the currently available information, preliminary investigation suggests that there is no significant human-to-human transmission, and no infections among health care workers have occurred.

But again, warned that travellers should take measures such as

  • avoiding close contact with people suffering from acute respiratory infections;
  • frequent hand-washing, especially after direct contact with ill people or their environment;
  • travellers with symptoms of acute respiratory infection should practice cough etiquette (maintain distance, cover coughs and sneezes with disposable tissues or clothing, and wash hands).

According to the WHO COVID-19 Timeline's entry for January 14th:

Dr. Maria Van Kerkhove noted in a press briefing there had been limited human-to-human transmission of the coronavirus (in the 41 confirmed cases), mainly through family members, and that there was a risk of a possible wider outbreak. Dr. Kerkhove noted that human-to-human transmission would not be surprising given our experience with SARS, MERS and other respiratory pathogens.

After WHO officials from its China and Western Pacific regional offices conducted a brief field visit to Wuhan from the 20th-21st of Jan, the latter office published a twitter thread on January 21st stating that as a result of the increasing number of cases of the virus; "It is now very clear [...] that there is at least some human-to-human transmission of #nCoV2019". The thread also states that "more information and analysis are needed on this new virus to understand the full extent of human-to-human transmission and other important details".

Additionally, on the 21st of January, the DON for the spread of the disease in the Republic of Korea contained the phrase "the extent of human-to-human transmission", the first DON not to question the existence of human-to-human transmission, but rather its extent.

A more formal announcement was made by the WHO mission to China on the 22nd of January which states that:

Data collected through detailed epidemiological investigation and through the deployment of the new test kit nationally suggests that human-to-human transmission is taking place in Wuhan. More analysis of the epidemiological data is needed to understand the full extent of human-to-human transmission. WHO stands ready to provide support to China to conduct further detailed analysis.

In conclusion then, while human-to-human transmission was suspected to be present from the initial WHO DON on January 5th, this was not confirmed until after data observed in the field in Wuhan by members of the WHO China & Western Pacific regional offices was thought to show that human-to-human transmission was clearly a factor. These field investigations took place on the 20th-21st of January, and announcements acknowledging this conclusion were first made on the 21st.


It's important to note that China had some evidence of human-to-human transmission as early as December 2019

The symptom onset date of the first patient identified was Dec 1, 2019. None of his family members developed fever or any respiratory symptoms. No epidemiological link was found between the first patient and later cases. The first fatal case, who had continuous exposure to the market, was admitted to hospital because of a 7-day history of fever, cough, and dyspnoea. 5 days after illness onset, his wife, a 53-year-old woman who had no known history of exposure to the market, also presented with pneumonia and was hospitalised in the isolation ward.

By late December, that evidence had grown considerably

The majority of the earliest cases included reported exposure to the Huanan Seafood Wholesale Market, but there was an exponential increase in the number of nonlinked cases beginning in late December.

While the WHO timeline might want to claim credit for noting that as early as Jan 14, that is contradicted by the WHO public statement it made that same day (as noted in the question). That same day Wuhan reiterated they did not believe COVID-19 was spreading from human to human (Google Translate below)

  1. As of now, have you found any cases of person-to-person transmission?

Existing findings indicate that there is no clear evidence of person-to-person transmission, and the possibility of limited person-to-person transmission cannot be ruled out, but the risk of continuing person-to-person transmission is low. At present, further research is being conducted in combination with clinical and epidemiological data.

It wasn't Jan 19, either, when the BBC has this quote from the WHO

Chinese officials say there have been no cases of the virus spreading from one person to another.

Instead, they say, the virus has crossed the species barrier and come from infected animals at a seafood and wildlife market in Wuhan.

The WHO's China office said the analysis was helpful and would help officials plan the response to the outbreak.

"Not enough is known to draw definitive conclusions about how it is transmitted, the clinical features of the disease, the extent to which it has spread, or its source, which remains unknown."

The first public WHO statement indicating human-to-human transmission came on Jan 22

Data collected through detailed epidemiological investigation and through the deployment of the new test kit nationally suggests that human-to-human transmission is taking place in Wuhan. More analysis of the epidemiological data is needed to understand the full extent of human-to-human transmission.

The WHO did not act like it believed its own reports

Just saying Jan 22 doesn't really explain why the linked stories are so critical.

Despite the fact that its own investigations were showing human-to-human transmission, the head of the WHO continued to criticize countries limiting or banning travel to China (article is dated Feb 03, but unclear what date the quotes come from)

WHO chief Tedros Adhanom Ghebreyesus says 151 cases of the disease and one death have been confirmed in 23 countries outside China. He says this small number of cases can be managed without countries resorting to extreme measures.

"There is no reason for measures that unnecessarily interfere with international travel and trade. We call on all countries to implement decisions that are evidence-based and consistent. WHO stands ready to provide advice to any country that is considering which measures to take,” Tedros said.

The WHO head then later praised China for limiting the outbreak (WHO speech from Feb 15)

We are encouraged that the steps China has taken to contain the outbreak at its source appear to have bought the world time, even though those steps have come at greater cost to China itself. But it’s slowing the spread to the rest of the world.

We’re encouraged that outside China, we have not yet seen widespread community transmission.

The WHO would finally declare a pandemic on Mar 11, long after COVID-19 had exploded worldwide

In the past two weeks, the number of cases of COVID-19 outside China has increased 13-fold, and the number of affected countries has tripled.

There are now more than 118,000 cases in 114 countries, and 4,291 people have lost their lives.

It contains these statements seemed more interested in blunting criticism

WHO has been assessing this outbreak around the clock and we are deeply concerned both by the alarming levels of spread and severity, and by the alarming levels of inaction.


And we have called every day for countries to take urgent and aggressive action.

We have rung the alarm bell loud and clear.

For some people, the conclusion they draw is that the WHO did not believe it was a seriously contagious disease until Mar 11, when the disease had already shut down most of the world.

  • 3
    The studies you linked do not necessarily support the conclusion that China "had" evidence. They are retrospective studies, the dates cited within are from etymological studies afterwards. Also, in the first fatal case (also the case of husband-to-wife transmission, the first reported case of limited H2H transmission), the husband had first signs of symptoms on December 20, 2019 and went to the hospital on December 27. Quoting the section with the first sentence regarding another case with onset from Dec 1 is rather misleading.
    – xngtng
    Apr 11, 2020 at 13:28
  • 3
    The Wuhan statement is consistent with WHO's timeline, "limited H2H transmission cannot be ruled out" vs. "may have been limited H2H". In the same Wuhan govt statement, you can find they reported the case of (possible) husband-to-wife transmission.
    – xngtng
    Apr 11, 2020 at 13:36
  • 5
    3/11 is the day they officially declared COVID-19 a pandemic, which is very different than saying it had was capable of human to human transmission. For something to be a pandemic, it must, by definition, already have spread around the world. No one should have taken the fact that it was not a declared pandemic to mean that it did not have the potential to be or was not likely to be one
    – divibisan
    Apr 12, 2020 at 1:24
  • 4
    Your bold headline "WHO did not act like it believed its own reports" is not supported by the evidence you have given. You are assuming, without cause, that large scale travel restrictions are the only way to combat a disease with H2H transmission. That is not the case. In particular, contact tracing can be effective in containing the spread of an infectious disease, and is far less disruptive. It was not known at the time that COVID-19 also spreads by asymptomatic people (or people with symptoms so mild they mistake COVID-19 for the common cold), which makes contact tracing less effective.
    – meriton
    Apr 12, 2020 at 11:21
  • 2
    Also, WHO is far from alone in being skeptical of travel restrictions: According to various scientists, travel restrictions can merely delay, not prevent, the arrival of the first case. That is, they do not contain the epidemic or lessen its impact, but merely delay it for a few weeks.
    – meriton
    Apr 12, 2020 at 14:31

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