People with flu are most contagious in the first days after their illness begins. Some otherwise healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Some people, especially young children and people with weakened immune systems, might be able to infect others for an even longer time. Onset of Symptoms. Complications of Flu. People at High Risk from Flu. Preventing Seasonal Flu.
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It was previously led by Dr. Wendy Keitel and is currently under the direction of Dr. Hana El-Sahly. The VTEU network conducts clinical trials that evaluate vaccines and treatments for a wide array of infectious diseases. An important strength of this established network is that it is able to efficiently and safely test new vaccines within a rapid time frame. The VTEU research group in the department has been involved in important studies that led to the licensure of live attenuated and high dose inactivated influenza virus vaccines.
They have tested vaccines to seasonal influenza and they have performed many studies evaluating vaccines targeting pandemic influenza, including the swine-origin H1N1, and the H5N1, H9N2, and H7N9 viruses, among others. They have evaluated methods to improve vaccine immunogenicity, including delivery of vaccine by different routes of administration, different dosages, and with different adjuvant preparations. Researchers involved in these studies include Drs.
Their hope is that the results of these studies will identify the optimal and most effective dosages of vaccine to protect the public from seasonal influenza, as well as from a possible influenza pandemic.
MVM investigators would like to better understand epidemic influenza seasonal flu infections, disease, and vaccines with the goal of developing ways to better control these epidemics. Towards this goal, they are working on developing new improved vaccines against epidemic influenza strains and are trying to understand how the immune systems of different people respond to the influenza virus and influenza vaccines.
In addition, MVM researchers with the VTEU have been evaluating the safety and immunogenicity of seasonal influenza vaccine in pregnant women. Because pregnant women are at higher risk for serious complications from the flu, it is important to develop strategies to protect these women from seasonal and pandemic influenza.
The clinical trial includes up to women recruited from nine sites across the nation and is headed by Dr. Shital Patel. It is one of the few studies that will evaluate antibody responses in pregnant women following vaccination. Evaluating the safety of seasonal inactivated influenza vaccine will yield vital information in anticipation of the need to test novel vaccines against possible future pandemic strains, in pregnant women.
Scientists are also conducting a study in collaboration with Kelsey-Seybold Clinics to determine the effectiveness of an inactivated influenza vaccine in protecting pregnant women and whether these immunized women can pass immunity against influenza to their infants, so that newborns would be protected from influenza during their first few months of life.
Another approach to protect against influenza epidemics is called herd immunity. The idea is to vaccinate a large percentage of school-age children to limit the spread of influenza without needing to vaccinate a larger percentage of the general population.
The reasoning behind this idea is that school-age children are often the source of infection and pass the virus onto their friends, teachers, and family members. This might be especially helpful to the elderly population who are at higher risk from influenza-related complications and whose immune systems may not mount as effective a response to influenza as younger individuals.
Another advantage to this approach is that it might be possible to achieve high community protection from influenza with a limiting amount of vaccine. Pedro Tony Piedra and colleagues are testing herd immunization in school-aged children in central Texas. In their initial study, they found that vaccination of 12 to 15 percent of children in selected communities resulted in an indirect protection to influenza infection in 8 to 18 percent of the adults in these communities.
They are currently conducting a larger, school-based vaccination program with the goal of immunizing 50 percent of the children, and they will determine how effective this level of immunization is in preventing infection in adults.
Piedra and co-workers want to know how many children need to be vaccinated in order to protect the adult population from influenza infection, and they would like to use this approach to control the spread of epidemic influenza.
They also hope to use this approach as a model for combating pandemic influenza and bioterrorism. Piedra has also investigated the effects of oseltamivir commonly known as Tamiflu on influenza-related complications in children with chronic medical conditions. Patients with underlying medical conditions are at higher risk of complications from both seasonal and pandemic flu. Piedra and his colleagues found that children with chronic medical conditions benefit from the use of Tamiflu if it is prescribed early in the disease process.
Children and adolescents between the ages of 1 and 17 who were at high risk of influenza complications showed significant reductions in the risks of respiratory illnesses other than pneumonia, reduced risk of otitis media a middle ear infection , and fewer hospitalizations in the 14 days after influenza diagnosis. The most effective way to prevent the widespread infection and high mortality rate that a new influenza virus could inflict upon the human population would be to vaccinate people, so that the human immune system would be prepared to fight off an infection.
MVM investigators are trying to identify the best way to prime the human immune system to defend against flu strains that could cause a pandemic. Researchers have been testing vaccines against H1N1, H5N1, H7N9, and other potential pandemic flu strains and analyzing the immune responses of different people to the vaccines.
Members of the Department were part of the national effort to prepare a vaccine against H1N1 influenza and test candidate vaccines. Several different parameters were tested: the number of doses required one or two , different dosage amounts 15 or 30 micrograms , and different age groups 18 to 64 years old, age 65 and older, and healthy children. The goal was to determine the reactions and antibody protection responses following immunization with experimental influenza H1N1 vaccine when given with seasonal influenza vaccine.
The trial enrolled healthy adults, and a similar trial was conducted with children aged 6 months to 17 years. Study participants received a single strength of the H1N1 vaccine given in two doses along with the seasonal flu vaccine given either before, during, or after the time that they were inoculated with the H1N1 vaccine. Scientists in the department also examined ways to optimize the collection of samples and testing for infection, analyzing immune responses , and working on epidemiological, pathogenesis , and treatment studies of the virus.
They worked on developing a method to collect samples and isolate viruses so that they could assess the viruses and the immune responses against them. Researchers used these samples to isolate the virus for further characterization and study how the immune system responds. These samples were banked and shared with researchers around the country.
The goal of this study was to help guide the process of vaccine development and to give scientists an idea of the response to antiviral chemotherapy and changes of the virus over time. MVM researchers have been involved in preparing assays used to detect the virus and evaluate immune responses.
The Respiratory Virus Diagnostic Research laboratory supports clinical trials on the epidemiology, immunology, pathogenesis, and vaccine prevention of important human respiratory pathogens and houses a cell culture lab for virus isolation and a polymerase chain reaction PCR lab for respiratory virus identification.
Under the direction of Dr. In addition, Dr. Robert Couch set up serologic assays for evaluation of immune responses. Studies conducted by MVM researchers helped guide public health officials in determining the best course of action in dealing with the H1N1 outbreak. They monitored vaccine recommendations made by the CDC and made suggestions. They kept the general public informed through local and national media outlets.
The scientists continue to study the H1N1 virus to gain a deeper understanding of the virus itself, its interactions with the immune system, and responses to the H1N1 vaccine. Additionally, researchers within the VTEU have been working on other new influenza strains that have pandemic potential including the new avian H7N9 virus and investigating vaccine strategies. This work will provide valuable information in responding to future influenza outbreaks. In more recent work, Dr. Robert Atmar and his colleagues have been conducting a phase 2 clinical trial to test a candidate for a universal flu vaccine known as M Unlike other flu vaccines, which consist of a whole inactivated flu virus or an attenuated live virus, the M vaccine is comprised of nine epitopes, short stretches of viral protein, that are common to many different influenza strains.
Because these regions are shared between different strains, it is hoped that the vaccine would trigger the immune system to respond to multiple strains. Adult healthy volunteers will receive the experimental vaccine or a placebo and will be monitored over time to evaluate their immune responses. Andrew Rice and colleagues are studying an avian influenza virus protein called NS1 that has recently been shown to be associated with virulence. Proteins like NS1 that are involved in pathogenesis are important targets for novel antiviral therapeutics.
The goal of this project is to identify cellular proteins that interact with NS1 and play a role in the pathogenesis of avian influenza virus infection. The PBM is predicted to associate with a class of cellular proteins - termed PDZ proteins - that are typically involved in cell-cell contact, cellular polarity, and signaling pathways.
A long-term goal of this project is to derive small molecules that can inhibit the interaction between the NS1 protein and its cellular PDZ protein targets, as such small molecules may be the basis for the development of novel therapeutics to treat avian influenza virus infection.
In a separate study, Dr. Venkataram Prasad and Zach Bornholdt, a graduate student in his laboratory, have determined the structure of a region of an important influenza protein called NS1. If you're young and healthy, the flu usually isn't serious. Although you may feel miserable while you have it, the flu usually goes away in a week or two with no lasting effects. But children and adults at high risk may develop complications that may include:.
Pneumonia is one of the most serious complications. For older adults and people with a chronic illness, pneumonia can be deadly. The flu vaccine can reduce your risk of the flu and its severity and lower the risk of having serious illness from the flu and needing to stay in the hospital.
Flu vaccination is especially important this season because the flu and coronavirus disease COVID cause similar symptoms. Preventing the flu and reducing the severity of flu illness and hospitalizations could also lessen the number of people needing to stay in the hospital.
This year's seasonal flu vaccine provides protection from the four influenza viruses that are expected to be the most common during the year's flu season. This year, the vaccine will be available as an injection and as a nasal spray. Avoid crowds. The flu spreads easily wherever people gather — in child care centers, schools, office buildings, auditoriums and public transportation.
By avoiding crowds during peak flu season, you reduce your chances of infection. Also avoid anyone who is sick. And if you're sick, stay home for at least 24 hours after your fever is gone so that you lessen your chance of infecting others. Your local health department and the CDC may suggest other precautions to reduce your risk of COVID or the flu if you haven't been fully vaccinated. For example, you may need to practice social distancing physical distancing and stay at least 6 feet 2 meters from others outside your household.
You may also need to wear a cloth face mask when indoors with people outside your household and when outdoors in crowded areas. If you're fully vaccinated and are in an area with a high number of new COVID cases in the last week, the CDC also recommends wearing a mask indoors in public and outdoors in crowded areas or when you're in close contact with unvaccinated people.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press. Older children and adults with flu appear to be most contagious during the initial days of their illness but many people remain contagious for about 7 days.
People who are hospitalized with severe disease and people with weakened immune systems can be contagious for 20 days or longer. Both COVID and flu can spread from person-to-person between people who are in close contact with one another within about 6 feet. Both are spread mainly by large and small particles containing virus that are expelled when people with the illness COVID or flu cough, sneeze, or talk. These particles can land in the mouths or noses of people who are nearby and possibly be inhaled into the lungs.
In some circumstances, such as indoor settings with poor ventilation, small particles might be spread further than 6 feet and cause infections. Although most spread is by inhalation, it may be possible that a person can get infected by touching for example, shaking hands with someone who has the virus on their hands or by touching a surface or object that has virus on it, and then touching their own mouth, nose, or eyes.
Both flu viruses and the virus that causes COVID can be spread to others by people before they begin showing symptoms; by people with very mild symptoms; and by people who never experience symptoms asymptomatic people.
This means the virus that causes COVID can quickly and easily spread to a lot of people and result in continual spreading among people as time progresses. Those at highest risk include:. Most people who get flu will recover on their own in a few days to two weeks, but some people will experience severe complications , requiring hospitalization. Some of these complications are listed above.
People at higher risk of complications or who have been hospitalized for COVID or flu should receive supportive medical care to help relieve symptoms and complications.
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