Cdc statistics h1n1 virus

The English language content on this website is being archived for historic and reference purposes only. Situation Update The U. Diagnosis How the illness is diagnosed, recommendations for lab testing…. Vaccination is the best protection we have against flu. CDC is now encouraging everyone to get vaccinated against H1N1. The vaccines to protect against H1N1 are widely available. Supplies of seasonal flu vaccine may be limited. Find a vaccine Influenza is thought to spread mainly person-to-person through coughing or sneezing of infected people.

Take everyday actions to stay healthy. As the outbreak unfolded, team structures and staffing were periodically assessed for functionality and utility. On April 23, , samples submitted by Texas revealed two additional cases of human infections with H1N1, transforming the investigation into a multistate outbreak and response. At the same time, CDC was testing 14 samples from Mexico, some of which had been collected from patients who were ill before the first 2 U.

California patients. Results from seven of the samples were positive for H1N1 and similar findings were reported for specimens submitted by Mexico to Canada. It had now become clear that cases were occurring in multiple countries and human to human spread of the virus appeared to be ongoing. That same day CDC held the first formal full press briefing to inform the media and guide the public and health care response to the rapidly evolving situation. CDC held nearly 60 press briefings during the H1N1 response.

On April 24, , CDC uploaded complete gene sequences of the H1N1 virus to a publicly-accessible international influenza database, which enabled scientists around the world to use the sequences for public health research and for comparison against influenza viruses collected elsewhere, and an updated report on the outbreak was published online in the MMWR.

On Saturday, April 25, , under the rules of the International Health Regulations, the Director-General of WHO declared the H1N1 outbreak a Public Health Emergency of International Concern and recommended that countries intensify surveillance for unusual outbreaks of influenza-like illness and severe pneumonia.

Also on April 25, , New York City officials reported an investigation into a cluster of influenza-like illness in a high school, and CDC testing confirmed two cases of H1N1 influenza infection in Kansas, and another case in Ohio shortly after. After the determination of the public health emergency, FDA also took action to expand possible usage of antiviral drugs oseltamivir and zanamivir by issuing Emergency Use Authorizations EUAs. This included allowing for off-label use of:.

On April 27, the WHO Director-General raised the level of influenza pandemic alert from phase 3 to phase 4 , based primarily on epidemiological data demonstrating human-to-human transmission and the ability of the virus to cause community-level outbreaks.

Based on reports of widespread influenza-like-illness and many severe illnesses and deaths in Mexico, CDC issued a travel health warning recommending that United States travelers postpone all non-essential travel to Mexico. As in past influenza seasons, CDC urged the public and especially those people at highest risk of influenza-related complications, to protect themselves by taking antiviral drugs early in their illness when recommended by their doctor; CDC also advised that everyone take every day preventive actions like covering coughs and sneezes and staying home from work and school when ill to help reduce the spread of illness.

On April 29, WHO raised the influenza pandemic alert from phase 4 to phase 5 , signaling that a pandemic was imminent, and requested that all countries immediately activate their pandemic preparedness plans and be on high alert for unusual outbreaks of influenza-like illness and severe pneumonia. The U.

Government was already implementing its pandemic response plan. CDC continued to post and update guidance for states, clinicians, laboratories, schools, partners and the public on topics ranging from the non-pharmaceutical measures communities could take to limit spread of disease, to how to evaluate a patient for possible infection with H1N1 influenza, to how to care for children who might be sick with H1N1 influenza.

Findings in Mexico indicated that transmission in Mexico involved person-to-person spread with multiple generations of transmission. The Dispatch suggested that the high school age students had respiratory and fever symptoms similar to those caused by a seasonal flu, but in addition, about half had diarrhea, which is more than expected with seasonal flu. As the details of the outbreak unfolded, the Federal response continued in high gear. Also on April 30, , HHS announced that the Federal government would purchase an additional 13 million treatment courses of antiviral drugs to help fight influenza.

The additional treatment courses would be added to the SNS. As the outbreak spread, CDC began receiving reports of school closures and implementation of community-level social distancing measures meant to slow the spread of disease. School administrators and public health officials were following their pandemic plans and doing everything they could to slow the spread of illness. Social distancing measures are meant to increase distance between people.

Measures include staying home when ill unless to seek medical care, avoiding large gatherings, telecommuting, and implementing school closures. While initial efforts were underway to develop a safe and effective vaccine to protect people against H1N1, work also was being done at CDC to help laboratories supporting health care professionals to more quickly identify the H1N1 virus in samples from patients.

Prior to the availability of this EUA, public health laboratories had been able to identify whether influenza A viruses were seasonal influenza viruses or were a novel strain, but the new diagnostic kits allowed labs to confirm a virus as H1N1. On May 1, , CDC test kits began shipping to domestic and international public health laboratories. Each test kit contained reagents to test 1, clinical specimens.

From May 1 through September 1, , more than 1, kits were shipped to domestic and international laboratories in countries. Once labs had the test kits and verified that their testing was running properly, they were able to identify new cases more quickly than before and no longer needed to send samples to CDC for lab confirmation.

By May 18, , 40 states had been validated to conduct their own H1N1 testing, with eight states having multiple laboratories able to do their own testing.

CDC alerted the public that the expansion in testing capacity would likely result in a jump in the number of H1N1 cases, but that this would actually present a more accurate picture of the true scope of H1N1 influenza in the United States. Probable cases were reported to CDC by state health departments and occurred in people who tested positive for influenza A and negative for seasonal influenza A H1N1 and A H3N2 subtypes at their state health department laboratory, but whose samples had not had confirmatory testing for the H1N1 influenza virus.

CDC deployed a large number of staff to the field to support the outbreak response; by May 1, , 50 staff people were deployed, and that number climbed to more than by May 11, , before gradually declining as field teams returned from deployment to complete studies, analyze collected data, and help inform policy decisions for the prevention and control of H1N1 influenza. Over the course of the outbreak, more than 3, people from throughout CDC would support the response.

On May 6, , CDC distributed recommendations for the use of influenza antiviral medicines to provide guidance for clinicians in prescribing antiviral medicines for treatment and prevention chemoprophylaxis of H1N1 influenza. CDC recommended that testing and antiviral treatment be prioritized for people with severe respiratory illness and people at high risk of complications from seasonal influenza.

This included children younger than 5 years old, pregnant women, people with chronic medical conditions, and people 65 years and older. By this point in the outbreak, about half of all influenza viruses being detected through laboratory surveillance were H1N1 viruses, with the other half being regular seasonal influenza viruses, including seasonal influenza A H1N1, influenza A H3N2 and type B viruses. The highest rates of hospitalization were among children younger than 5 years of age; the next highest hospitalization rate was in people 5 years to 24 years of age.

Based on data from previous influenza pandemics and seasonal influenza, pregnant women had been recognized as a high-risk group early in the outbreak.

This article emphasized the importance of empiric treatment treatment without confirmatory testing of pregnant women suspected to have H1N1. People with other previously recognized medical conditions that placed them at high risk of complications from seasonal influenza also appeared to be at increased risk of complications from H1N1 influenza.

Reported deaths had occurred in people ranging in age from 22 months old to 57 years old. Early results of an antibody study conducted by CDC indicated that children had no existing cross-reactive antibody to the H1N1 influenza virus, while about one-third of adults older than 60 years of age had cross-reactive antibody against the H1N1 flu virus.

One possible explanation for this pre-existing antibody in older adults was that they may have had previous exposure, either through infection or vaccination, to an influenza A H1N1 virus that was more closely related to the H1N1 flu virus than contemporary seasonal influenza A H1N1 viruses are.

Data from a similar study suggested that seasonal influenza vaccine would not provide any significant protection against H1N1 influenza virus. On June 11, , WHO signaled that a global pandemic of H1N1 influenza was underway by further raising the worldwide pandemic alert level to Phase 6.

The press conference had a total of 2, participants. At the time, more than 70 countries had reported cases of H1N1 infection, and community level outbreaks of H1N1 were ongoing in multiple parts of the world. The WHO decision to raise the pandemic alert level to Phase 6 was a reflection of spread of the virus in other parts of the world and not a reflection of any change in the H1N1 influenza virus or associated illness.

To date, most people in the United States who had become ill with H1N1 influenza had not become seriously ill and had recovered without hospitalization. After the WHO declaration of a pandemic on June 11, the H1N1 virus continued to spread and the number of countries reporting cases of H1N1 nearly doubled from mid-June to early July Additionally, CDC estimated that ,, people worldwide died from H1N1 pdm09 virus infection during the first year the virus circulated.

This differs greatly from typical seasonal influenza epidemics, during which about 70 percent to 90 percent of deaths are estimated to occur in people 65 years and older. Though the flu pandemic primarily affected children and young and middle-aged adults, the impact of the H1N1 pdm09 virus on the global population during the first year was less severe than that of previous pandemics.

Estimates of pandemic influenza mortality ranged from 0. It is estimated that 0. However, H1N1 pdm09 virus continues to circulate as a seasonal flu virus, and cause illness, hospitalization, and deaths worldwide every year. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Influenza Flu. Section Navigation. Influenza pandemics of the 20th century.

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