During the past 3 weeks, new major epidemic foci of coronavirus disease 2019 (COVID-19),
some without traceable origin, have been identified and are rapidly expanding in Europe,
North America, Asia, and the Middle East, with the first confirmed cases being identified
in African and Latin American countries. By March 16, 2020, the number of cases of
COVID-19 outside China had increased drastically and the number of affected countries,
states, or territories reporting infections to WHO was 143.
On the basis of ”alarming levels of spread and severity, and by the alarming levels
of inaction”, on March 11, 2020, the Director-General of WHO characterised the COVID-19
situation as a pandemic.
The WHO Strategic and Technical Advisory Group for Infectious Hazards (STAG-IH) regularly
reviews and updates its risk assessment of COVID-19 to make recommendations to the
WHO health emergencies programme. STAG-IH's most recent formal meeting on March 12,
2020, included an update of the global COVID-19 situation and an overview of the research
priorities established by the WHO Research and Development Blueprint Scientific Advisory
Group that met on March 2, 2020, in Geneva, Switzerland, to prioritise the recommendations
of an earlier meeting on COVID-19 research held in early February, 2020.
In this Comment, we outline STAG-IH's understanding of control activities with the
group's risk assessment and recommendations.
To respond to COVID-19, many countries are using a combination of containment and
mitigation activities with the intention of delaying major surges of patients and
levelling the demand for hospital beds, while protecting the most vulnerable from
infection, including elderly people and those with comorbidities. Activities to accomplish
these goals vary and are based on national risk assessments that many times include
estimated numbers of patients requiring hospitalisation and availability of hospital
beds and ventilation support. Most national response strategies include varying levels
of contact tracing and self-isolation or quarantine; promotion of public health measures,
including handwashing, respiratory etiquette, and social distancing; preparation of
health systems for a surge of severely ill patients who require isolation, oxygen,
and mechanical ventilation; strengthening health facility infection prevention and
control, with special attention to nursing home facilities; and postponement or cancellation
of large-scale public gatherings.
Some lower-income and middle-income countries require technical and financial support
to successfully respond to COVID-19, and many African, Asian, and Latin American nations
are rapidly developing the capacity for PCR testing for COVID-19.
Based on more than 500 genetic sequences submitted to GISAID (the Global Initiative
on Sharing All Influenza Data), the virus has not drifted to significant strain difference
and changes in sequence are minimal. There is no evidence to link sequence information
with transmissibility or virulence of severe acute respiratory syndrome coronavirus
the virus that causes COVID-19.
SARS-CoV-2, like other emerging high-threat pathogens, has infected health-care workers
in China4, 5 and several other countries. To date, however, in China, where infection
prevention and control was taken seriously, nosocomial transmission has not been a
major amplifier of transmission in this epidemic. Epidemiological records in China
suggest that up to 85% of human-to-human transmission has occurred in family clusters
and that 2055 health-care workers have become infected, with an absence of major nosocomial
outbreaks and some supporting evidence that some health-care workers acquired infection
in their families.4, 5 These findings suggest that close and unprotected exposure
is required for transmission by direct contact or by contact with fomites in the immediate
environment of those with infection. Continuing reports from outside China suggest
the same means of transmission to close contacts and persons who attended the same
social events or were in circumscribed areas such as office spaces or cruise ships.6,
Intensified case finding and contact tracing are considered crucial by most countries
and are being undertaken to attempt to locate cases and to stop onward transmission.
Confirmation of infection at present consists of PCR for acute infection, and although
many serological tests to identify antibodies are being developed they require validation
with well characterised sera before they are reliable for general use.
From studies of viral shedding in patients with mild and more severe infections, shedding
seems to be greatest during the early phase of disease (Myoung-don Oh and Gabriel
Leung, WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School
of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong,
Special Administrative Region, China, personal communication).8, 9 The role, if any,
of asymptomatic carriers in transmitting infection is not yet completely understood.
Presymptomatic infectiousness is a concern (Myoung-don Oh and Gabriel Leung, personal
communication)8, 9 and many countries are now using 1–2 days of symptom onset as the
start day for contact identification.
A comprehensive report published by the Chinese Center for Disease Control and Prevention
on the epidemiological characteristics of 72 314 patients with COVID-19 confirmed
previous understanding that most known infections cause mild disease, with a case
fatality ratio that ranged from 2·9% in Hubei province to 0·4% in the other Chinese
This report also suggested that elderly people, particularly those older than 80 years,
and people with comorbidities, such as cardiac disease, respiratory disease, and diabetes,
are at greatest risk of serious disease and death. The case definition used in China
changed several times as COVID-19 progressed, making it difficult to completely characterise
the natural history of infection, including the mortality ratio.
Information on mortality and contributing factors from outbreak sites in other countries
varies greatly, and seems to be influenced by such factors as age of patients, associated
comorbidities, availability of isolation facilities for acute care for patients who
need respiratory support, and surge capacity of the health-care system. Individuals
in care facilities for older people are at particular risk of serious disease as shown
in the report of a series of deaths in an elderly care facility in the USA.
The pandemic of COVID-19 has clearly entered a new stage with rapid spread in countries
outside China and all members of society must understand and practise measures for
self-protection and for prevention of transmission of infection to others. STAG-IH
makes the following recommendations.
First, countries need to rapidly and robustly increase their preparedness, readiness,
and response actions based on their national risk assessment and the four WHO transmission
for countries with no cases, first cases, first clusters, and community transmission
and spread (4Cs).
Second, all countries should consider a combination of response measures: case and
contact finding; containment or other measures that aim to delay the onset of patient
surges where feasible; and measures such as public awareness, promotion of personal
protective hygiene, preparation of health systems for a surge of severely ill patients,
stronger infection prevention and control in health facilities, nursing homes, and
long-term care facilities, and postponement or cancellation of large-scale public
Third, countries with no or a few first cases of COVID-19 should consider active surveillance
for timely case finding; isolate, test, and trace every contact in containment; practise
social distancing; and ready their health-care systems and populations for spread
Fourth, lower-income and middle-income countries that request support from WHO should
be fully supported technically and financially. Financial support should be sought
by countries and by WHO, including from the World Bank Pandemic Emergency Financing
Facility and other mechanisms.
Finally, research gaps about COVID-19 should be addressed and are shown in the accompanying
and include some identified by the global community and by the Research and Development
Blueprint Scientific Advisory Group.
Research gaps that need to be addressed for the response to COVID-19
Fill gaps in understanding of the natural history of infection to better define the
period of infectiousness and transmissibility; more accurately estimate the reproductive
number in various outbreak settings and improve understanding the role of asymptomatic
Comparative analysis of different quarantine strategies and contexts for their effectiveness
and social acceptability
Enhance and develop an ethical framework for outbreak response that includes better
equity for access to interventions for all countries
Promote the development of point-of-care diagnostic tests
Determine the best ways to apply knowledge about infection prevention and control
in health-care settings in resource-constrained countries (including identification
of optimal personal protective equipment) and in the broader community, specifically
to understand behaviour among different vulnerable groups
Support standardised, best evidence-based approach for clinical management and better
outcomes and implement randomised, controlled trials for therapeutics and vaccines
as promising agents emerge
Validation of existing serological tests, including those that have been developed
by commercial entities, and establishment of biobanks and serum panels of well characterised
COVID-19 sera to support such efforts
Complete work on animal models for vaccine and therapeutic research and development
The STAG-IH emphasises the importance of the continued rapid sharing of data of public
health importance in medical journals that provide rapid peer review and online publication
without a paywall. It is sharing of information in this way, as well as technical
collaboration among clinicians, epidemiologists, and virologists, that has provided
the world with its current understanding of COVID-19.