WHO Declares H1N1 Pandemic Over, Urges Continued Influenza Vigilance
Washington, D.C., August 10, 2010 (PAHO) — The World Health Organization (WHO) announced today that the 2009 H1N1 pandemic has effectively ended, and the world has moved into a “post-pandemic” phase characterized by traditional seasonal patterns of influenza.
“The new H1N1 virus has largely run its course,” WHO
Director-General Dr. Margaret Chan said in a telephone news conference.
“During the pandemic, H1N1 crowded out other influenza viruses to become
the dominant circulating virus. This is no longer the case.”
The announcement came following a meeting earlier today of the
Emergency Committee of the International Health Regulations (IHR), which
consists of leading experts on influenza who provide advice to WHO
based on the latest epidemiological and virological data.
Dr. Chan said the committee’s advice to declare an end to the
pandemic was based on the global situation but also took into account
significant influenza activity in several countries. Among the key
factors considered were:
- Influenza outbreaks worldwide have returned to levels of intensity that are characteristic of normal influenza seasons.
- H1N1 is no longer the dominant influenza virus but is part of a mix of circulating viruses.
- Large numbers of people now have some immunity to the H1N1 virus as a result of infection, exposure, or vaccination campaigns.
Dr. Chan cautioned, however, that ongoing vigilance is needed to ensure
that the virus does not unexpectedly reemerge as a threat. “We expect
the virus to continue to circulate for some years to come.”
Dr. Mirta Roses, Director of the Pan American Health Organization
(PAHO), joined Dr. Chan in emphasizing the need for continued vigilance,
especially on the part of PAHO/WHO member countries in Latin America
and the Caribbean.
“Influenza viruses are highly unpredictable. We need to keep up
surveillance and reporting to ensure that we are not taken by surprise
as a result of any such change,” said Dr. Roses.
During the past 16 months, the 2009 H1N1 pandemic virus reached
every WHO region and affected all but a handful of the world’s
countries. Officially, the virus has caused approximately 18,500 deaths.
That figure, however, is based only on laboratory-confirmed cases. Dr.
Keiji Fukuda, WHO’s leading influenza expert, described the number as a
“minimum” and said it may take several years to develop more accurate
death toll numbers based on traditional methods of estimating influenza
In the Americas, more than 8,500 laboratory-confirmed deaths due to
H1N1 have been reported (as of early August) to PAHO. Outbreaks in Latin
America and the Caribbean peaked in April–August 2009 and, in a number
of countries, stretched the capacity of national health systems to
handle the large number of cases. Among the hardest hit countries were
Mexico and the countries of the Southern Cone.
Dr. Roses noted that the H1N1 virus continues to circulate at low
levels, along with other influenza viruses, in Latin America and the
Caribbean and that it could still cause outbreaks that could have
significant effects on local communities.
Moreover, the H1N1 virus could change—through antigenic drift—in
ways that make people’s current immunity less protective. In addition,
countries that were less affected during the pandemic could see more
severe disease from H1N1 in a future season.
For these reasons, PAHO is urging health authorities in its member countries in Latin America and the Caribbean to:
- Maintain surveillance of influenza virus, influenza-like illness and
severe acute respiratory illness, and monitor and investigate unusual
events, such as clusters of severe respiratory illness or death.
- Report to PAHO/WHO changes such as sustained transmission of
antiviral-resistant H1N1 virus, human cases of infection with any
influenza virus not known to be circulating in human populations, or
significant changes in the epidemiological or genetic characteristics of
H1N1 or other influenza viruses.
- Continue to vaccinate against the H1N1 virus, using monovalent
(single virus) H1N1 vaccine or trivalent seasonal vaccine (which now
contains H1N1), depending on availability. This is particularly
important for high-risk groups, including pregnant women.
- Continue to provide appropriate care for people suspected of illness
from influenza, including treatment with anti-viral medicines for
groups at increased risk of severe illness.
Dr. Roses also said that PAHO member countries should
review their national pandemic preparedness plans and make improvements
to those plans based on experience gained during the 2009 H1N1
“We believe our work with member countries on preparing for a
pandemic was a valuable investment in building capacity for surveillance
and reporting and in strengthening health systems in general. But there
is still much work to be done in both of these areas to ensure that our
countries are better prepared for the next health emergency, whatever
that might be.”
PAHO was established in 1902 and is the world’s oldest public health
organization. It works with all the countries of the Americas to
improve the health and quality of life of the people of the Americas and
serves as the Regional Office for the Americas of the World Health
CONTACT: Donna Eberwine-Villagran, email:
, Tel. +1 202 974 3122, Knowledge Management and
Communication Area, PAHO/WHO – www.paho.org