COVID-19 Resource Center

COVID-19 Resource Center

March 09, 2020
4 min read

WHO says pandemic threat of COVID-19 ‘very real,’ but could be controlled

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

Tedros Adhanom Ghebreyesus
Tedros Adhanom Ghebreyesus

The outbreak of COVID-19 is nearing the level of a pandemic, according to WHO.

“Now that the virus has a foothold in so many countries, the threat of a pandemic has become very real,” WHO Director-General Tedros Adhanom Ghebreyesus, PhD, MSc, said during a press briefing. “But it would be the first pandemic in history that could be controlled. The bottom line is that we’re not at the mercy of the virus.”

Recently, WHO announced that cases of COVID-19 have surpassed 100,000 and were identified in more than 100 countries.

Tedros explained that the uneven spread of the epidemic worldwide suggests that countries should develop a tailored response that focuses on both containment and mitigation.

Regardless of whether a country has no cases, sporadic cases or clusters of cases, Tedros noted that the response to COVID-19 should involve identifying, testing, treating and isolating cases and monitoring patients’ contacts. In countries with community spread, he said it becomes more difficult to test every suspected case and trace patients’ contacts, and therefore actions like cancelling school and large events are necessary, along with other public health efforts to reduce exposure to the COVID-19 virus.

Places like Singapore and South Korea — where the number of infections has gone down thanks to public health efforts — demonstrate that in regard to this outbreak, “the name of the game is never give up,” Tedros said.

Michael Ryan, MD, executive director of the WHO Health Emergencies Program, said during the briefing that WHO has not yet declared the outbreak a pandemic in part because there is no set definition of a COVID-19 pandemic and also because of concerns about the potential international response to the declaration of a pandemic.

“[T]he word is important because in many situations, [it] involves countries moving towards purely a mitigation approach, and what we’ve seen is that moving to a purely mitigation approach is saying that the disease will spread in an uncontrolled fashion,” he said.

In addition to the briefing by WHO, new data from the CDC and research published in the Annals of Internal Medicine shed light on the extent of the outbreak in the United States and the risk for infection.

CDC discusses US cases, travel recommendations

The CDC announced during a press conference that more than 500 cases of COVID-19 have been reported across 34 states and Washington, D.C., with the highest number of cases reported in California and Washington.


The agency also announced that 78 state and local laboratories across 50 states can now screen up to 75,000 people with CDC test kits, and that more of these test kits are expected to be distributed “soon,” according to Nancy Messonnier, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases. Vice President Mike Pence said during a press briefing on Friday that both LabCorp and Quest Diagnostics will have tests available for sale across the country this week.

Regarding the risk for infection, the CDC stated that data from 70,000 cases reported in China show that only about 2% occurred in patients younger than 19 years of age.

“This seems to be a disease that affects adults and most seriously older adults,” Messonnier said during the press conference.

She explained that an increased risk for disease starts at age 60 years and further increases with age. The highest risk for serious illness and death is among those aged 80 years and older. There is also a higher risk for death and serious illness among those with underlying health conditions, according to Messonnier.

Due to the elevated risks experienced by these groups, Messonnier said the CDC recommends “that travelers, particularly those with underlying health issues, defer all cruise ship travel worldwide. We also recommend that people at higher risk avoid nonessential travel, such as long plane trips.”

She noted that no one younger than 30 years of age has died in South Korea from COVID-19 and no one younger than 50 years of age has died in Japan due to the disease, which is “why it’s so important for older adults and people with serious underlying health conditions to be prepared,” Messonnier said.

Although the CDC notes that its recommendations are subject to change based on new evidence, its current recommendation to actively monitor people who are exposed to the COVID-19 virus for 14 days has been backed by a newly published study.

Incubation period

This research published in the Annals of Internal Medicine shows that patients infected with the COVID-19 virus, SARS-CoV-2, may be symptom free for an average of 5 days.

“Based on our analysis of publicly available data, the current recommendation of 14 days for active monitoring or quarantine is reasonable, although with that period some cases would be missed over the long term,” Justin Lessler, PhD, an associate professor in the Bloomberg School's Department of Epidemiology at Johns Hopkins University, said in a press release.


Lessler and colleagues analyzed 181 cases of COVID-19 from Wuhan, China, and other countries that were detected before Feb. 24, 2020. They collected information on cases from news reports, public health reports and press releases. The cases included in the study had information on the likely date of SARS-CoV-2 exposure and the date of symptom onset.

Of the cases, most involved people who were from or who traveled to Wuhan, China, or who had been exposed to people from the Hubei province in China.

Researchers estimated the median incubation period of SARS-CoV-2 was 5.1 days (95% CI, 4.5-5.8). They also determined that 97.5% of symptomatic patients developed these symptoms within 11.5 days of infection (95% CI, 8.2-15.6).

The findings suggest that 101 of every 10,000 cases of COVID-19 could develop symptoms after 14 days of active monitoring or quarantine.

“Whether this rate is acceptable depends on the expected risk for infection in the population being monitored and considered judgment about the cost of missing cases,” Lessler and colleagues wrote. “Combining these judgments with the estimates presented here can help public health officials to set rational and evidence-based COVID-19 control policies.” – by Erin Michael


Lauer S, et al. Ann Intern Med. 2020;doi: 10.7326/M20-0504.

Disclosures: Lessler reports receiving a grant from the CDC during the conduct of the study. Please see study for all other authors’ relevant financial disclosures. Messonnier, Ryan and Tedros report no relevant financial disclosures.