News & Events

H1N1 (“Swine”) Flu statistics update from MDPH

Massachusetts, National and International H1N1 Activity
Exclusion Period (Updated)
School Guidance (Updated)
MMWR-Evaluation of Rapid Influenza Diagnostic Tests
Novel H1N1 Influenza Vaccine
Novel H1N1 Influenza Vaccine Safety
Seasonal Influenza Vaccine

Massachusetts H1N1 Flu Activity

As of August 6, 2009, 1,383 confirmed cases of H1N1 have been reported throughout Massachusetts. As of July 30, there have been 5,514 hospitalized cases of H1N1 nationally, with 353[1] deaths.

Table 1. Confirmed H1N1 cases in MA, as of 8/6/09

Age Group (N)

Age group (%)

Female (%)

Pregnant (N)

Hospitalized (N)

Hospitalized (%)

Deaths (N)

0-4 years








5-11 years








12-18 years








19-25 years








26-44 years








45-64 years








65+ years
























As shown in Table 1 above, school-aged individuals (5-18 years) have been primarily affected by H1N1, with 63% of cases age 18 or younger. The median age of cases is 14 years and cases ranged in age from 0 to 84 years. To date, males and females have been equally impacted by H1N1. Overall, 176 cases have been hospitalized (12.7%), which is similar to the national hospitalization rate of 11% as of July 10, and 10 cases have died. Of the 10 deaths, 8 had underlying conditions

National Flu Activity Update

  • Influenza illness, including illness associated with the novel influenza A (H1N1) virus, is ongoing in the U.S. As of August 7, 2009, 6,506 total novel influenza A (H1N1) hospitalizations, and 436 total deaths have been reported to CDC by state and local public health departments.
  • CDC estimates that between April and June 2009, more than 1 million cases of novel H1N1 flu occurred in the United States.
  • The August 7 FluView Report shows that influenza activity decreased in the United States during July 26 – August 1, 2009, compared to the previous week; however, there are still higher levels of influenza-like illness than is normal for this time of year (see graph below).
  • Novel H1N1 flu outbreaks are ongoing in parts of the U.S., in some cases with intense activity. Novel H1N1 viruses now make up more than 98% of all sub-typed influenza A viruses analyzed by the U.S. WHO/NREVSS collaborating laboratories.
  • Since September 28, 2008, CDC has received 98 reports of laboratory confirmed influenza-associated pediatric deaths that occurred during the 2008-09 influenza season, 30 of which were due to novel influenza A (H1N1) virus infections.
  • CDC anticipates that novel H1N1 viruses will co-circulate with regular seasonal influenza viruses over our influenza season. The timing, spread and severity of novel H1N1 virus – in addition to our regular seasonal influenza viruses – are uncertain.

International Situation Update as of August 4, 2009

  • Novel influenza A (H1N1) continues to circulate widely. Descriptive epidemiology of cases remains similar across countries. Isolates sequenced at WHO and CDC suggest that circulating novel influenza A (H1N1) viruses look similar to California/07/2009 (the reference virus selected by WHO as a potential candidate for novel influenza A (H1N1) vaccine).
  • The novel influenza A (H1N1) virus is the dominant influenza virus in circulation in the U.S., England, South Africa, New Zealand, Australia, Chile, Argentina and Brazil. South Africa has had a notable increase in the proportion of influenza that is novel influenza A (H1N1), and now it represents the majority of influenza in the country.
  • Many seasonal influenza viruses from these countries have not been subtyped. Of those that have been subtyped in Australia, South Africa, and Argentina, the most common seasonal influenza virus is influenza A (H3N2).

Exclusion Period

  • On August 5, CDC revised its recommendation about how long people with flu-like illness should stay home and away from other people to prevent spreading the flu. CDC now recommends that those with flu-like illness stay home until at least 24 hours after their fever is gone, without using fever-reducing medicines like acetaminophen or ibuprofen.
  • Previously, CDC had recommended that people stay home for seven days after they became ill or 24 hours after they had no symptoms, whichever was longer. The change in recommendation is based on what we learned about the new H1N1 virus during spring 2009 and is designed to decrease the risk of spreading the flu while also reducing the disruption to society caused by people staying home for long periods.
  • During spring 2009, most people infected with the new H1N1 flu had fevers for 2-4 days. By tailoring the recommendation to how long someone with flu has a fever, people with less severe illnesses will be able to return to their daily lives sooner, while also protecting others from the flu during their most contagious period.
  • The new recommendation applies to camps, schools, businesses and other community settings where most people are not at high risk for flu complications. It does not apply to healthcare settings.
  • The recommendations for healthcare remain at 7 days after symptoms began or until all symptoms are gone, whichever is longer.
  • The guidance applies to all people who have the flu or flu-like illness, even if they are taking antiviral drugs. It’s important that those with flu-like illness stay home while sick, except to seek medical care, and avoid contact with other people. People give off more flu virus when they have a fever. So staying home during this time will be especially important to not spread the flu to friends, co-workers and fellow students.
  • Even when fever has subsided, people can continue giving off the flu virus. They should take steps to protect others, like voiding close contact with people they know are at high risk of flu complications, frequently washing hands and covering their mouths and noses when coughing or sneezing.
  • Because not everyone ill with the new H1N1 flu will have a fever, it is important for everyone to wash their hands frequently and follow good hand hygiene and respiratory etiquette so they don’t unknowingly infect others.
  • State and local health departments may decide to lengthen the time period that people should stay home. This will be especially important for those who are returning to a place where there are many people at high risk for flu complications, such as a camp for children with asthma or a childcare facility for children less than 5 years old.
  • CDC will update the guidance as more information becomes available.

School Guidance

  • On August 7, CDC released new guidance to help schools promote a safer environment for their students and staff and reduce exposure to influenza during the 2009-10 school year. The new guidance is designed to decrease the spread of regular seasonal flu and the new H1N1 flu while limiting the disruption of day-to-day activities and the vital learning that goes on in schools.
  • By implementing these recommendations, schools and health officials can help protect a fifth of the country’s population from flu. This guidance provides a menu of tools to fight flu that school officials can enact, in coordination with local health officials, based on conditions in their area and what CDC and other public health organizations are learning about the virus.
  • We know far more about the new H1N1 flu virus than we did when it was first detected in April. We know that closing schools is not the best option in most cases.
  • The options schools use should match the severity of the illness that’s being reported and local flu activity.
    • For an outbreak similar to the spring H1N1 outbreak, CDC recommends stepping up basic good hygiene practices like hand washing, keeping sick students and staff away from school and helping families identify their children who are at high-risk for flu complications and would benefit from early evaluation from their physician if they develop the flu.
    • If outbreaks become more severe, CDC recommends extending the time that sick people are away from school, allowing people at high risk for flu to stay home, actively watching for signs of illness in students and staff and considering preemptive school dismissal.
  • The recommendations will be most effective when implemented together as a package that combines good hygiene and practices to keep those who are ill separated from those who are well, with more active interventions based on the severity of the flu outbreak.
  • We do anticipate more illness from the new H1N1 influenza than this past spring and more school-based outbreaks because influenza is typically transmitted more easily in fall and winter. By taking planning steps now schools can help ensure they’re prepared for any future flu activity.
  • Updated Guidance and Toolkit for Schools for the Fall Flu Season: CDC announced updated federal guidelines to offer state and local public health and school officials a range of options for responding to 2009 H1N1 influenza in schools, depending on how severe the flu may be in their communities. The guidance says officials should balance the risk of flu in their communities with the disruption that school dismissals will cause in education and the wider community. To access the guidance, and toolkit for schools, use the following link:
  • School Policies Technical Report The comprehensive technical report on school policies including school exclusions and closure can be found at

Recommendations for outbreak similar to spring 2009

  • Hand Hygiene/Respiratory etiquette
  • Emphasize the importance of promoting basic foundations of preventing flu: getting vaccinated, frequent hand washing with soap and water when possible, covering noses and mouths with a tissue when coughing or sneezing and staying home when sick.
  • CDC recommends that:
    • All children aged 6 months up to their 19th birthday get a seasonal flu vaccine.
    • All children from 6 months through 18 years of age receive the new H1N1 flu vaccine when it becomes available.
    • Alcohol-based hand sanitizers can be used if soap and water are not available. In places where alcohol-based sanitizers are not allowed, other sanitizers can be substituted but may not work as well.
    • If tissues are not available, coughing or sneezing into the arm or sleeve is recommended.
    • Schools should provide time for students to wash their hands whenever necessary and make tissues readily available to students and staff.
  • Exclusion period
    • Those with flu-like illness should stay home for at least 24 hours after they no longer have a fever, without use of fever-reducing medicines and regardless of whether or not they are using antiviral drugs.
    • Those who are sick should stay in the home during this period, except to seek necessary medical care and should avoid contact with others.
  • Routine cleaning
    • People can sometimes get flu if they touch droplets left on hard surfaces and objects by those who are ill and then touch their eyes, nose or mouth.
    • Studies have shown that influenza virus can survive on environmental surfaces and can infect a person for up to 2-8 hours after being deposited on the surface.
    • School staff should routinely clean areas that students and staff touch often with the cleaners they typically use. Special cleaning with bleach and other special cleaners is not necessary.
    • Environmental cleaning should not be the primary focus of influenza prevention activities.
  • Separate ill students and staff
    • Students and staff who appear to have flu-like illness should be sent to a room separate from other students until they can be sent home. CDC also recommends they wear a surgical mask if possible.
    • Space is often a challenge in schools, so it’s essential that schools begin to identify this area now. It should not be an area that’s used for other purposes like a lunchroom.
    • Schools should limit the number of staff who cares for ill students before they can be sent home. Those caring for students should wear protective gear, such as a mask.
    • Consider selectively dismissing students and staff. Schools that serve pregnant students or medically fragile students* may consider dismissing schools if they cannot protect students from flu with classes in session.

* For this guidance, a medically fragile child is a child who needs intensive, life sustaining medical assistance or therapy, and needs assistance with daily living (for example, a child who uses an oxygen tank, has trouble moving, is fed through a tube, needs suctioning, or is on a ventilator). Many of these children need skilled nursing care and special medical equipment. These medically fragile children may have chronic lung disease, severe cerebral palsy, muscular dystrophy, immunodeficiency, or problems with their metabolism.

  • Decisions should be based on the severity of disease in the community and should be made in collaboration with local and state public health officials.

Recommendations for outbreaks of INCREASED SEVERITY

  • If the influenza viruses circulating during the 2009-10 school year cause higher rates of severe illness, hospitalizations and deaths, communities should consider adding interventions like permitting high risk students, such as those who are pregnant or have chronic medical conditions, to stay home and dismissing school.
  • Except for school dismissals, these strategies have not been scientifically proven. But we want school and health officials to have tools in their toolbox that they can use if it seems like the right measure for their community and the circumstances.
  • Decisions about what measures to implement should be made jointly by school and local health officials.
  • Extended exclusion period (Increased Severity Scenario)
    • Under this scenario, people with flu-like illness should stay home for at least 7 days after illness onset, even if they have no more symptoms. People who are still sick after 7 days should stay home for at least 24 hours after all their symptoms are gone.
    • Let high-risk students and staff members stay home
    • Those at high risk of flu complications and their families may want to talk to their doctor about staying home from school when a lot of flu is circulating in the community.
    • Schools should plan now for ways to continue educating students who stay home, through instructional phone calls, homework packets, internet lessons, and other approaches.
    • Schools also must develop contingency plans to fill important positions like school nurses if regular staff members are ill or home with ill family members. Schools should identify healthcare workers in the community who would be willing to volunteer at the school.
    • It will be important for those people who stay home to avoid becoming ill also avoid other places where they might catch the flu, like large public gatherings.
  • Active screening (Increased Severity Scenario)
    • Parents should check their children each morning for illness and should keep children home if they have a fever. Medications that decrease fevers like acetaminophen don’t prevent the spread of flu virus, so it’s important to stay home when sick with flu, even if taking medicine.
    • Schools should also check students and staff for fever and other symptoms of flu when they get to school in the morning, separate those who are ill, and send them home as soon as possible.
  • Keep siblings home (Increased Severity Scenario)
    • Students who have an ill family member should stay home for 5 days from the day that their family member got sick. This is the time period that they’re most likely to get sick themselves.
  • Increase distance at schools (Increased Severity Scenario)
    • By keeping the same children together throughout the day, schools can help reduce spread of the flu. We encourage schools to try innovative ways of separating students. These can be something as simple as moving desks farther apart to more drastic changes such as rotating teachers between classrooms with the same students, and canceling classes that bring together children from different classrooms.
  • School dismissals (Increased Severity Scenario)
    • School officials should balance the risks of flu in their community with the disruption dismissals will cause in both education and the wider community.
    • Decisions should be made locally and can include dismissing when absenteeism is excessive, and proactively closing schools to decrease the spread of flu.
    • Schools that dismiss students should do so for at least 5-7 calendar days and should reassess whether or not to resume classes. Based on the reason for dismissing school (in reaction to outbreaks vs. preemptively), the amount of time schools are dismissed may be longer.
    • Parents should start thinking now about how they might handle a school dismissal, as these decisions may be made very quickly.


  • When seasonal influenza or the new H1N1 flu is widespread in the community, action should be taken to protect the most vulnerable students and staff.
  • High-risk groups for influenza complications include:
    • Children younger than 5 years old;
    • Pregnant women;
    • Children and adolescents (younger than 18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye’s syndrome after influenza virus infection;
    • Adults and children who have chronic pulmonary disease (such as asthma); cardiovascular, hepatic, hematological, neurologic, neuromuscular, or metabolic disorders, such as diabetes; adults and children who are immunosuppressed;
    • Residents of nursing homes and other chronic-care facilities;
    • And those who are 65 or older.
    • For more information:

MMWR-Evaluation of Rapid Influenza Diagnostic Tests

  • The August 7, 2009 Morbidity and Mortality Weekly Report article, “Evaluation of Rapid Influenza Diagnostic Tests for Detection of Novel Influenza A (H1N1) Virus—United States, 2009” evaluates three commercially available rapid influenza diagnostic tests (RIDTs) for their ability to detect novel influenza A (H1N1).
  • Rapid Influenza Diagnostic tests (RIDTs) are tests that detect influenza A or B antigens and can provide results within 15 minutes.
  • RIDTs from three companies were evaluated and results indicate that these tests can detect novel influenza A (H1N1) in respiratory specimens, but the overall sensitivities range from 40-69% meaning that many novel influenza A (H1N1) infections will be missed. Given the lower sensitivities found with RIDTs compared to reverse transcriptase-polymerase chain reaction (rt-PCR), decisions regarding treatment and further testing among patients with negative results from RIDT testing should be based upon clinician suspicion, underlying medical conditions, severity of illness, and risk for complications in those persons suspected of having novel H1N1 virus infection.
  • Early treatment with influenza antiviral medications of persons infected with influenza who are at increased risk of influenza complications and those people hospitalized with suspected influenza is important to maximize benefit of treatment and to lessen the severity of illness. Antiviral treatment should not be withheld pending the results of diagnostic testing if the suspicion for novel H1N1 virus infection is high.
  • On Wednesday, July 29th, CDC issued "Interim Guidance for the Detection of Novel Influenza A Virus Using Rapid Influenza Diagnostic Tests." This guidance updates previous guidance on this topic and is available at

Novel H1N1 Influenza Vaccine

  • CDC’s Advisory Committee on Immunization Practices (ACIP), a panel made up of medical and public health experts, met July 29, 2009, to make recommendations on who should receive the new H1N1 vaccine when it becomes available, and to determine which groups of the population should be prioritized if the vaccine is initially available in limited quantities.
  • The Committee recommended that initial vaccination efforts focus on five key populations:
    • all people 6 months through 24 years of age
    • people who live with or care for children younger than 6 months of age
    • all pregnant women
    • healthcare and emergency services personnel, and people aged 25 through 64 years who have health conditions associated with higher risk of medical complications from influenza.
  • Together, these key populations equal 159 million (approx. 3.4 million in Massachusetts). By vaccinating these priority groups we hope to reduce the impact of H1N1.
  • People in these groups are at higher risk of disease or serious complications, likely to come in contact with novel H1N1, or who could infect young infants. Vaccinating persons who live with or care for children <6 months is the best way to help protect these children since those there is no influenza vaccine for children <6 months.
  • Once the demand for vaccine for these prioritized groups has been met at the local level, programs and providers should begin vaccinating everyone from the ages of 25 through 64 years.
  • Current studies indicate that the risk for infection among persons age 65 or older is less than the risk for younger age groups. Many older adults seem to already have some existing immunity to the novel H1N1 virus. However, as vaccine supply and demand for vaccine among younger age groups is being met, programs and providers should also offer vaccination to people 65 years and older.
  • Availability and demand for vaccine can be unpredictable. It is possible that initial amounts of vaccine will not be enough to meet demands. If vaccine is available in insufficient amounts for the initial priority groups, the following groups would be prioritized:
    • pregnant women
    • people who live with or care for children younger than 6 months of age,
    • healthcare and emergency services personnel with direct patient contact,
    • children 6 months through 4 years of age, and
    • children 5 through 18 years of age who have chronic medical conditions.
  • Novel H1N1 vaccine supply and availability is projected to increase quickly over time, and vaccine should not be kept in reserve for later administration of the second dose.
  • The novel H1N1 vaccine is not intended to replace the seasonal flu vaccine – it is intended to be use along-side seasonal flu vaccine to protect people.
  • It is anticipated that seasonal flu and novel H1N1 vaccines may be administered on the same day.
  • The U.S. will soon begin an initial set of five clinical trials of candidate novel H1N1 influenza vaccines. The research will be under the direction of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. More information about these clinical trials can be found at
  • The five manufacturers who already produce U.S.-licensed seasonal vaccine are also conducting their own novel H1N1 influenza vaccine trials under contract with HHS.
  • If things progress to full scale production, some H1N1 vaccine may be available as early as mid-September.
  • The novel H1N1 influenza vaccine will be made using the same processes and facilities that are used to make the currently licensed seasonal influenza vaccines.
  • CDC will provide the public with transparent information about what we know and do not know about the safety and efficacy of novel H1N1 vaccines to help them make informed decisions.
  • A mass vaccination program of even a modest scale will involve extraordinary efforts at the federal, state and local levels.

Novel H1N1 Influenza Vaccine Safety

  • The novel H1N1 flu vaccines will be very much like seasonal flu vaccines, which have a very good safety profile. However, no vaccine is 100% safe. This vaccine will be no exception. Those who choose vaccination for themselves or their children will be screened for contraindications (such as egg allergy) and will receive information sheets describing the vaccine’s risks and benefits, signs and symptoms of adverse events to look for following vaccination, and how to report adverse events.
  • CDC expects that H1N1 vaccines will be available in multiple formulations, including a formulation that does not contain th preservative thimerosal.
  • CDC is working to enhance our safety monitoring systems and will actively encourage providers and vaccine recipients to report to us adverse events following vaccination (whether or not they believe the vaccine caused the event). We will be monitoring very closely for any signs that the vaccine is causing unexpected adverse events and we will work with state and local health officials to investigate any unusual events rapidly.

Seasonal Influenza Vaccine

  • The new H1N1 influenza virus is a reminder of the unpredictable nature of influenza, and the importance of prevention. While the novel H1N1 influenza virus has been the focus of attention since the spring, it is important that we do not forget the risks posed by seasonal influenza viruses.
  • Every year in the United States, on average 5% to 20% of the population gets the flu; more than 200,000 people are hospitalized from flu complications, and; about 36,000 people die from flu-related causes. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious complications from seasonal influenza.
  • The single best way to protect yourself and your loved ones against the flu is to get vaccinated each year. We hope that people, especially those at high risk for serious complications and their close contacts, will start to go out and get vaccinated in September or as soon as vaccine is available at their doctors’ offices or in their communities.
  • It is not too early to get a flu vaccine as soon as it is available in August or September. The protection you get from the vaccine will not wear off before the flu season is over.
  • While we hope that people who want to avoid getting seasonal influenza will not delay getting vaccinated, we know that some will. We will be encouraging them to get vaccinated throughout the influenza season, into December, January, and beyond.
  • Annual flu vaccines contain three viruses: one A (H1N1) virus, one A (H3N2) virus and one B virus. The viruses in the vaccine change each year based on international surveillance and scientists’ estimations about which types and strains of viruses will circulate in a given year.
  • The fact that annual flu vaccines contain an A (H1N1) virus may cause some confusion. The novel H1N1 influenza virus that has caused the current pandemic is not the same as the H1N1 virus in the seasonal flu vaccine. We want to make sure that we communicate clearly to the public that the seasonal flu vaccine is not expected to protect against the novel H1N1 influenza virus. There are efforts underway to develop a safe and effective novel H1N1 vaccine.
  • As always, it’s not possible for us to predict at this time of year whether this year’s seasonal vaccine will be a good match with circulating viruses. Influenza viruses are constantly changing – they can change from one season to the next or they can even change within the course of the same season.
  • Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time.
  • Because of these factors, there is always the possibility of a suboptimal match between circulating viruses and the viruses in the vaccine.
  • While a less than ideal virus match can reduce the vaccine’s effectiveness against the variant virus, the vaccine can still offer cross-protection against related influenza viruses and prevent many illnesses and flu-related complications.

Donna Lazorik, RN, MS
Adult Immunization Coordinator
Massachusetts Department of Public Health
MDPH Flu Website: