Dr. Tom Frieden, Former CDC Director, on the Latest Scientific Developments, and Implications for Novel Coronavirus Prevention and Control
At the end of a busy week of our usual work at Resolve to Save Lives in epidemic prevention and cardiovascular health, combined with requests to advise on and discuss the rapidly evolving coronavirus outbreak, I sat down to read seven scientific articles about coronavirus that had come out in the past day. These give us more information than we’ve ever had, but leave many key questions unanswered. Our understanding of nCov2019 is rapidly evolving – with new information nearly every hour. These findings can be revised or reversed - early in an outbreak, there's a "fog of war" reality. The first case in the epi-curve that was just published (see Figure) was from December 1, and there was no uptick in cases until around December 20, with the first alert reported on December 31 – a relatively rapid reporting interval.
Here’s a quick summary of the key findings from the scientific publications:
It’s now highly likely that, as suspected, the ancestral source is bats and the first location may have been the wet market in Wuhan – detailed genetic analysis as well as the largest epidemiological investigation published to date show that 27 of 41 initial cases had exposure to the market. As noted, this virus and bat coronaviruses are close relatives. (Why are bats the cause of so many bad pathogens for people? They are mammals and live in huge cities... sound familiar?)
This coronavirus behaves somewhat like SARS, which it resembles genetically, but is much less deadly, and possibly more infectious. In particular, it seems to attack the lower respiratory tract, because of receptor binding to ACE2, which is found predominantly in the lung. Symptoms are mostly related to the lung, and x-rays show viral pneumonia. The virus, which is an RNA virus prone to replication errors, may well mutate and evolve in the coming months and years.
Superspreader events – one individual or event resulting in many infections – are likely to occur or to have occurred, as they did with both SARS and MERS.
Nosocomial transmission (spread within health care facilities), which was a major source of spread for MERS and SARS, has occurred and remains a major risk for nCov2019 – and is also a major intervention point for control. (The link above is to a familial cluster which may have started with nosocomial transmission. Although this is not proven, it’s clear that nosocomial transmission is occurring.)
From a meticulous description of a family outbreak, it appears that the incubation period may be 3-6 days, at least for some patients, and it is proven that the disease can spread within a household.
One of the leading global units that models disease outbreaks estimates that the reproductive rate, Ro, has been 2.6 (estimated range 1.5-3.5) so far. This is a high number that is consistent with rapid spread observed. The authors note that Ro can decrease as control measures are implemented, but note: “Whether the reduction in transmission is sufficient to reduce R to below 1 – and thus end the outbreak – remains to be seen.”
At least one hospital in Wuhan has begun a clinical trial of antiviral agents.
In addition, public reports indicate increasing recognition of cases in many areas of China, and cases are being identified in an increasing number of countries on several continents. It’s possible that nCov2019 will spread more readily than SARS did, although we don’t know that yet.
What does that all mean?
We still don’t know how infectious the disease is and will remain, but it certainly has been infectious.
We still don’t know the denominator – how many people are infected, what proportion don’t have symptoms (although some are without symptoms, including a 10-year-old child), what proportion have mild illness – so we still don’t know the case fatality rate. However, at this point it appears likely that the mortality rate is lower than it was for SARS (11% for SARS vs. 3-4% so far for nCov2019 – 25 deaths out of 835 diagnosed patients initially, although some of those 835 may die, and the total number infected is undoubtedly much higher than 835, hence the actual mortality rate is likely to be lower, and perhaps far lower).
What should be done?
For most people in the US, nothing different. Wash your hands regularly. Cover your mouth and nose when you cough or sneeze. Don’t go to Wuhan, and consider other travel to China carefully – discuss with your doctor. (For staff in China – work from home to the greatest extent possible, avoid crowds and, if possible, avoid health care facilities unless you’re sick.)
Meticulous infection control in hospitals in China and other areas with infected patients, including rapid detection and isolation of patients with cough, respiratory protection, gloves, disinfection, and the other strategies that controlled SARS and MERS in hospitals. This will protect health workers and decrease the amplification of spread of the virus.
Get more epidemiologic information. How many episodes of nosocomial transmission have there been? What has been studied for each? There’s a big difference if the virus has been spreading from high-risk, aerosol-generating procedures such as sputum induction and bronchoscopy, as opposed to spread in waiting rooms and through other casual contact. Have there been superspreader events? For each recognized outbreak with transmission links, what are the most likely modes of spread and what control measures have been tried, with what effect?
Intensive laboratory work, including testing symptomatic patients (and, in some special studies, contacts), developing serological tests, and collecting multiple virus specimens to monitor for genetic changes.
Establish additional sentinel sites in China to determine what proportion of people both with and without symptoms who attend health care facilities are infected.
Each country should review its ability to find, stop, and prevent coronavirus cases
In the medium term, decide whether live markets should be regulated far more strictly, or closed completely. This won’t change the current outbreak, but allowing the current arrangement to continue, which leads to outbreaks, is not a responsible option.
Dr. Tom Frieden (www.DrTomFrieden.net) is former director of the US Centers for Disease Control and Prevention, and former commissioner of the New York City Health Department. He is currently president and CEO of Resolve to Save Lives, a global non-profit initiative of Vital Strategies, working with countries to prevent 100 million deaths and make the world safer from epidemics. Twitter @DrTomFrieden.
Links to articles cited and linked above:
A Novel Coronavirus from Patients with Pneumonia in China, 2019, New England Journal of Medicine
Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China, The Lancet
Another decade, another coronavirus, New England Journal of Medicine
Coronavirus infections, more than just the common cold, JAMA
A Novel Coronavirus Emerging in China – Key Questions for Impact Assessment, New England Journal of Medicine
Transmissibility of 2019-nCoV, Imperial College.