What to Know About mFlusiva, the New mRNA Flu Vaccine

Sep 15, 2026 | Cold and Flu, Family Medicine, Featured, Infectious Diseases, Vaccines, Your Health

For the first time, adults age 50 and older in the United States can get an mRNA flu vaccine.

The U.S. Food and Drug Administration (FDA) approved mFlusiva®, the first mRNA flu vaccine, in August 2026. Moderna makes mFlusiva. It uses the same basic vaccine technology as mRNA COVID-19 vaccines. But it targets influenza.

Unlike traditional flu vaccines, mFlusiva does not contain a live or killed influenza virus, or pieces of the virus. Instead, it uses messenger RNA (mRNA). This gives temporary instructions to your immune system, your body’s natural defense system. The instructions help it learn to recognize influenza.

This new approach might even have an edge over traditional flu vaccines.

“There is some evidence that suggests mFlusiva may offer somewhat better protection against the flu than traditional flu vaccines,” says Rebecca Choudhury, MD, Assistant Professor of Medicine (Infectious Diseases), Icahn School of Medicine at Mount Sinai.

How does mFlusiva work? How well does it protect against the flu? What do we know about safety and side effects? Dr. Choudhury explains the new mRNA flu vaccine and gives advice on getting your flu shot.

Rebecca Choudhury, MD, Assistant Professor of Medicine (Infectious Diseases), Icahn School of Medicine at Mount Sinai

How does mFlusiva work, and how is it different from traditional flu vaccines?

Traditional flu vaccines show the influenza virus or parts of it to the immune system. This teaches the immune system to recognize and fight the virus later. Depending on the vaccine, that may mean a killed virus, a weakened virus, or pieces of the virus.

mFlusiva is an mRNA vaccine. It does not contain a living or dead virus. It also does not contain viral parts. The vaccine uses messenger RNA designed to produce influenza surface proteins called hemagglutinin.

An image of the mFlusiva mRNA flu vaccine. Image credit: Moderna

It’s the same basic principle used by mRNA COVID-19 vaccines. But the target is different. COVID-19 vaccines tell cells to make the coronavirus spike protein. mFlusiva tells cells to make an influenza surface protein.

“This flu vaccine is creating a different protein, but the principle of how it works is the same,” says Dr. Choudhury.

Is mFlusiva more effective than traditional flu vaccines?

In one trial in adults age 50 and older, about 2 percent of people who received mFlusiva developed influenza confirmed by lab testing within six months of vaccination. By comparison, 2.8 percent of people who received a standard-dose flu vaccine developed influenza. The mFlusiva group had a 27 percent lower rate of flu.

For adults 65 and older, there is an important caveat. People in this age group typically receive a high-dose or adjuvanted flu vaccine rather than the standard-dose vaccine used in this trial. An adjuvanted vaccine has an added ingredient that helps the vaccine work better.

Studies comparing the immune response to mFlusiva with a high-dose flu vaccine have been encouraging. Immune response means how the body reacts to a vaccine to build protection.

“However, a stronger immune response does not necessarily mean better protection against actually getting the flu,” Dr. Choudhury notes.

Another study is expected to directly compare clinical outcomes between mFlusiva and a high-dose flu vaccine in adults 65 and older.

Is mFlusiva safe? What are the side effects?

Clinical trials so far suggest mFlusiva has a safety profile similar to traditional flu vaccines for serious adverse events. These are harmful or unexpected medical problems or side effects.

In a trial comparing mFlusiva with a standard-dose flu vaccine, serious vaccine-related adverse events were very rare. They occurred at similar rates in both groups.

Researchers also looked closely at heart-related events because of concerns previously raised about mRNA COVID-19 vaccines.

One participant who received mFlusiva developed cardiomyopathy and pericarditis. These are two heart-related conditions. This happened about three months later. It was unclear whether the vaccine caused them. One participant in the traditional flu vaccine group also developed pericarditis.

Dr. Choudhury says current data do not show a higher risk of these events with mFlusiva than with traditional flu vaccines.

The main difference so far is short-term side effects. Injection-site reactions, headaches, body aches, and fatigue occurred more often with mFlusiva than with traditional flu vaccines. This was seen across multiple studies.

“These symptoms are generally relatively mild, they go away on their own without any sort of treatment,” Dr. Choudhury says.

What are the advantages of an mRNA flu vaccine?

“The advantages are less so in how the vaccine itself works, and more so in how the vaccine is made,” Dr. Choudhury says.

Each year, scientists must predict which influenza strains will circulate months before flu season. Traditional flu vaccines take several months to produce. That can make it hard to change the vaccine if the strains that circulate are different from those expected.

Because mRNA vaccines do not rely on growing influenza virus in a lab, they can be produced more quickly. Dr. Choudhury says this could give vaccine makers more flexibility. They can update an mRNA vaccine when an unexpected flu strain begins circulating.

That flexibility could help produce flu vaccines that more closely match the strains actually circulating. It could also potentially improve how well seasonal flu vaccines protect people.

Who can get mFlusiva, and who may want to consider it?

mFlusiva is approved for adults age 50 and older. Based on the evidence so far, Dr. Choudhury says adults ages 50 to 64 may have the clearest reason to consider it.

People ages 50 to 64 typically receive a standard-dose flu vaccine. That was the same type used in the clinical trial. The trial found a lower rate of influenza among mFlusiva recipients.

Dr. Choudhury says mFlusiva may be especially worth considering for adults ages 50 to 64 with long-lasting (chronic) health conditions. These conditions can raise the risk of severe influenza. They include high blood pressure (hypertension), diabetes, chronic kidney or liver disease, obesity, or chronic lung disease.

Adults 65 and older can also receive mFlusiva. However, researchers are still gathering stronger clinical evidence. The studies compare mFlusiva with the high-dose or adjuvanted flu vaccines typically recommended for this age group.

Still, choosing between vaccines should not stop you from getting vaccinated.

“Ultimately, the best flu vaccine is the flu vaccine that you can get,” Dr. Choudhury says. If mFlusiva is not easy to get, she recommends getting an appropriate flu vaccine from your doctor’s office, pharmacy, or workplace rather than going without vaccination.

Can an mRNA flu vaccine change your DNA?

No. The mRNA in mFlusiva cannot change your DNA. It also cannot become part of your genetic code.

Dr. Choudhury says this has confused some people. Some worry that mRNA could reprogram their genetic code. But that’s not how the technology works.

Like other mRNA vaccines, mFlusiva gives cells temporary instructions to make a specific protein. Here, that protein is an influenza surface protein. The mRNA is then quickly broken down by the body.

“The mRNA in mFlusiva cannot become part of your genome,” says Dr. Choudhury.

When should you get your flu shot?

Flu season typically begins around October. Infections often peak around December. But the timing can vary from year to year.

Your immune system needs about two weeks after vaccination to build protection. Dr. Choudhury recommends planning ahead. The same timing applies to mFlusiva.

“I typically get the flu vaccine myself around early October,” Dr. Choudhury says.

Getting vaccinated is important even if you don’t consider yourself at high risk for serious problems from the flu. Influenza can cause severe illness that requires a hospital stay. Even a less serious case can leave you sick in bed for a week or longer.

“Getting your flu shot is a very easy, safe and effective step you can take to reduce your risk of getting sick and reduce your risk of making others sick,” Dr. Choudhury says.

Have questions about the new vaccine? Talk with your doctor.

What to Know About the Cyclospora Stomach Illness Outbreak

Updated on Jul 20, 2026 | Featured, Infectious Diseases, Your Health

You have probably heard about the Cyclospora outbreak, a stomach illness affecting a number of people in New York and across the country. Cyclospora is a parasite that can infect food and water, and the disease it causes is called cyclosporiasis. While the risk is considered low, there are a number of ways to protect yourself.

In this Q&A, Daniel Caplivski, MD, an infectious disease doctor with Mount Sinai, explains what to know about Cyclospora infection and how to prevent it.

A headshot of Daniel Caplivski, MD

Daniel Caplivski, MD

What are the symptoms?
Many people do not experience symptoms. In rare cases, Cyclospora can cause severe diarrhea. Cyclospora infection is usually not life threatening.

What is the risk that I might contract Cyclospora infection?
Overall risk remains low for the general population. We often see food-borne infections in clusters of the population.

Who is most at risk?
People with compromised immune systems, such as cancer patients undergoing chemotherapy and people with severe autoimmune diseases, are at risk for more severe diarrhea.

How do you know if you have Cyclospora?
We have special testing on stool specimens, including molecular testing and acid fast staining. This helps us identify parasites that are difficult to grow in culture systems. If you have severe diarrhea and vomiting that gets better then returns more than once, you should see a doctor and get checked.

How can I avoid it?
Your can avoid Cyclospora infection by:

  • Cooking your vegetables (this kills the parasite)
  • Thoroughly washing fresh fruits and vegetables (helps prevent spread)
  • Avoiding prewashed packaged lettuce unless you wash it again yourself
  • Wash your hands with soap and water thoroughly before handling raw fruits and vegetables

What are the treatments?
We have antibiotics that help treat patients with severe cases, but most people recover with supportive care, such as drinking plenty of fluids and getting rest. And your doctor may suggest an anti-diarrheal medicine.

What is causing the current outbreak?
The Centers for Disease Control and Prevention is investigating the source of the current outbreak. Prior outbreaks have been linked to raspberries, prewashed lettuce, basil, and snow peas.

Find a Mount Sinai doctor who specializes in Infectious Diseases
Learn more about Cyclospora on the CDC website.

Here’s What You Should Know About the New Hepatitis B Vaccine Recommendation

Jan 5, 2026 | Children's Health, Family Medicine, Featured, Infectious Diseases, Pediatrics

For several decades, federal guidelines regarding hepatitis B vaccination for infants in the United States had been unchanged and consisted of a first shot given at birth, a second at 1-2 months, and a third at 6-18 months.

In December 2025, the Centers for Disease Control and Prevention (CDC) announced new recommendations for hepatitis B vaccinations. For infants born to mothers who test negative for hepatitis B, the agency recommended the initial shot only at two months or after, and for infants to undergo antibody testing to determine whether the second and third shots are needed.

“The medical community hasn’t changed its stance on hepatitis B vaccinations, however,” says Daniel Caplivski, MD, Professor of Medicine (Infectious Diseases) at the Icahn School of Medicine, and Director of the Icahn School of Medicine Travel Medicine Program.

Daniel Caplivski, MD, Professor of Medicine (Infectious Diseases) at the Icahn School of Medicine at Mount Sinai (left), and Roberto Posada, MD, Professor of Pediatrics (Infectious Diseases) at the Icahn School of Medicine at Mount Sinai (right).

“Hepatitis B is a virus that, for many people, once they get the infection, they have it for the rest of their lives,” says Roberto Posada, MD, Professor of Pediatrics (Infectious Diseases) at the Icahn School of Medicine at Mount Sinai. “It can lead to cirrhosis of the liver and liver cancer, both of which are very preventable through childhood vaccination.”

Why are medical experts recommending that infants receive hepatitis B vaccinations at birth and to receive all shots? Drs. Caplivski and Posada explain the rationale behind the schedule and other facts about the virus.

Why should babies be vaccinated for hepatitis B at birth?
Dr. Posada: This recommendation had been in place since 1991. There are a few reasons why medical experts had pushed for hepatitis B vaccination for infants at birth. Usually, we check pregnant women for hepatitis B. But some people might not have access to full prenatal care, or the check sometimes gets missed. A mother in that situation can unknowingly pass hepatitis B on to the child. Vaccination at birth can prevent that.

Another reason is that the opportunity to protect the child is highest at the moment of childbirth. Once a child and mother are discharged, they might not return for follow-up appointments, or do so at the appropriate times. Thus, giving the hepatitis B vaccination right at childbirth at least provides that initial protection.

What’s the risk of waiting to vaccinate infants for hepatitis B?
Dr. Posada: For infants, other than hepatitis B being passed from the mother, the virus can be transmitted to some degree through household exposure to someone who has hepatitis B. For example, sharing utensils, an infant putting a parent’s toothbrush in the mouth—these are not the main ways of contracting the disease, but they can happen. We want to vaccinate the kids in the event there is someone in the household with hepatitis B.

Other than for infants, the main way hepatitis B is transmitted is through sexual transmission or contact with contaminated blood, such as via needles. That’s another reason to vaccinate children before they become sexually active.

Is the hepatitis B vaccine effective at preventing transmission?
Dr. Caplivski: Ever since we adopted the practice of vaccinating infants at birth, the rate of infants and children contracting hepatitis B has dropped to practically zero.

And the success of vaccinating at childbirth has been replicated around the world. In China, after they adopted a three-dose vaccination schedule from birth, the prevalence of hepatitis B carriers under 5 years old fell from 10 percent to around 0.3 percent in 10 years. That’s a lot of lives saved from chronic complications of the disease.

What could be the consequences of contracting hepatitis B?
Dr. Posada: If a baby gets it at birth, they’re very likely to have it for the rest of their life. And because the infection is lifelong, the more chances for cirrhosis, liver failure, or liver cancer to develop in the lifetime. Someone who contracts it at an older age has a higher chance of clearing the infection from the body.

Dr. Caplivski: The long-term consequences of liver failure and cancer are incredibly difficult for a patient. It is a medically intensive disease, but it also has a huge impact on health care expenditures. All of these could be avoided through vaccinations at childbirth.

According to statistics from the CDC, about 9 in 10 infants who become infected go on to develop lifelong chronic infection. The risk goes down as a child gets older. About 1 in 3 children who get infected before age 6 will develop chronic hepatitis B. Approximately 15–25 percent of people with chronic infection develop chronic liver disease, including cirrhosis, liver failure, or liver cancer.
Is it safe for infants to be vaccinated at childbirth?
Dr. Posada: The vaccine is a recombinant vaccine—meaning it is not a live virus; it is only protein from the virus synthesized in the lab. It cannot cause infection. Other than discomfort at the time of injection, we have had decades of data showing that hepatitis B vaccination at childbirth is safe.
Would the new recommendation by CDC create any access changes?

Dr. Caplivski: Historically, insurers have used CDC recommendations to base their coverage of vaccinations. While the federal entity is retreating from actively recommending hepatitis B vaccinations at childbirth, don’t forget that state departments of health can have their own recommendations and intervene if needed. In the case of New York State, there has been no change in guidelines, and we are still actively recommending hepatitis B vaccinations at childbirth.

What the new CDC action might have caused is a worsening of vaccine skepticism. Even in that situation, it is worth speaking with your pediatrician and health provider to learn more about what is the right course of action for you and your child.

Dr. Posada: Besides talking to your pediatrician, there are other sources of information that are well trusted, such as the American Academy of Pediatrics. It has very good information about childhood vaccines. At the end of the day, as doctors, we want your children to be healthy too.

 

Stories Behind the Science: Preparing to Fight the Next Epidemic

Updated on Sep 9, 2025 | COVID-19, Featured, Research

Stories Behind the Science: Preparing to Fight the Next Epidemic

Kris White, PhD, Assistant Professor of Microbiology at the Icahn School of Medicine at Mount Sinai (right), and lab member Isidora Suazo, PhD, Postdoctoral Fellow (left), are part of a research network to discover new drugs for a viral epidemic preparedness initiative.

It was June 2022, and Peter White, a lawyer from Point Lookout, Long Island, was in Florida attending a work event. As he was waiting for his flight home, he started to feel sick.

“By the time I landed, I was very sick with a heavy pressure in my chest,” said Mr. White, 67. “Any time I had previously felt like this, it had always, at a minimum, developed into bronchitis or pneumonia.”

Mr. White was worried it was COVID-19, which could spell poor outcomes given his underlying respiratory condition. “When I get a cold, it has a tendency to morph into bronchitis and, at times, pneumonia. I’ve had walking pneumonia several times, as well as regular pneumonia,” he said. “I can’t count the number of times I have had bronchitis.”

His doctor advised him to go to the emergency room to seek treatment for COVID-19. Thankfully, just months prior—in December 2021—the antiviral medication Paxlovid (nirmatrelvir/ritonavir) from Pfizer had become available via emergency use authorization for the treatment of COVID-19.

“I did not feel better right away,” Mr. White recalled. “However, I did not get worse, which was huge given my prior history, and it was a comfort for me that the drug was working.”

“Thankfully, his bout with COVID-19 ended up being uneventful, because he was able to take Paxlovid quickly and clear it out of his system,” said Kris White, PhD, Assistant Professor of Microbiology at the Icahn School of Medicine at Mount Sinai and Mr. White’s son.

“The COVID-19 pandemic really taught us the value of having treatments ready to test and deploy quickly when an epidemic hits,” said Dr. White.

Mount Sinai has been working toward that goal, in part through its involvement in the Antiviral Drug Discovery (AViDD) Centers for Pathogens of Pandemic Concern, established in 2022 by the National Institutes of Health (NIH). Dr. White’s lab is among several at Mount Sinai contributing research as part of the AViDD Centers, developing antiviral drugs to tackle future outbreaks.

Dr. White (second from right) with his father, Peter (second from left), with five of Dr. White’s children and two nieces. Peter caught COVID-19 in 2022, but with Paxlovid antiviral treatment, it did not develop into something severe, for which Mr. White was at high risk.

However, recent cuts to NIH funding have threatened to stall progress. “We were halfway to the finishing point,” said Dr. White. “With our funding cut, it is like we have half a drug—and that is of no good to anyone.”

Read about how antiviral research can help us navigate future epidemics, and challenges the AViDD Centers face.

‘It Could Have
Been A Very
Different Pandemic’

The issue with relying solely on pharmaceutical companies to develop drugs for an epidemic is that until the health crisis is at hand, there is no incentive for them to carry out such research, noted Dr. White.

That was the case with COVID-19—when it hit in early 2020, there were few if any drug candidates to test right away. Pharmaceutical companies and academic institutions scrambled to find new compounds, or repurpose old ones, that could treat the infection.

Pfizer had a lead, PF-07321332, which had potential for targeting SARS-CoV-2, the virus that causes COVID-19. It was developed in 2003 to address the severe acute respiratory syndrome (SARS) outbreak in 2002-2004. But before it could make it into human clinical trials, the outbreak was contained and development was discontinued.

Even promising compounds take time before they can be used on patients. It wasn’t until March 2021 that Pfizer announced it would test PF-07321332 in humans in a phase 1 trial. In June that year, a phase 2/3 trial was carried out to test its effectiveness, and in December, the compound, which had been named Paxlovid, received its emergency-use authorization.

“We’ve seen that given the will, we can quickly test the effectiveness and safety of treatments and make them available to the public,” said Dr. White. “Imagine if we had compounds ready to test right at the beginning, it could have been a very different pandemic.”

For Dr. White’s father, that difference was between life and death. “Paxlovid was a game changer for me,” said Mr. White. “Knowing that I was most likely going to suffer, but not die, from COVID-19 was good news. It would have been better if this drug was available sooner rather than later.”

Having treatments available early on not only reduces transmission, disease severity, and mortality rates, but also has an impact on health policy.

“Having such an antiviral could even have mitigated the need for severe lockdowns, or even vaccine mandates,” said Dr. White. For people who might be ineligible for vaccines, or were resistant to such mandates, having a treatment available would have provided options for health providers and policymakers, he explained.

March 2020

The World Health Organization declares COVID-19 a pandemic.
September 2020

Pfizer completes pharmacokinetic study of PF-07321332 in rats.
March 2021

PF-07321332 tested in a first-in-human phase 1 trial.
June 2021

Phase 2/3 trial for PF-07321332 begins.
December 2021

PF-07321332 receives emergency-use authorization from the FDA, is named Paxlovid.

Kickstarting the Process

Dr. White, seen dressed in protective clothing, works with Biosafety Level 2 and Biosafety Level 3 viruses as part of his work. His lab’s research includes drug discovery of new antivirals and building up animal models of viral infection.

Following the authorization of Paxlovid, the National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, realized the benefits of having promising drug candidates ready to be tested at the onset of an outbreak.

“Academic institutions like Mount Sinai were perfectly suited for kickstarting that discovery work,” said Dr. White, whose lab studies viral-host interactions, develops cell culture and animal models of viral infection, and performs other antiviral drug discovery work.

Members of Dr. White’s lab, from left to right: Briana McGovern, BS, Senior Research Associate; Meg Gordon, BA, Research Associate; Dr. White; Dr. Suazo; Jared Benjamin, MS, Research Associate.

“Historically, drug discovery was a process that took billions of dollars, and was usually undertaken by pharmaceutical companies,” said Dr. White. “Now, with technological advances and artificial intelligence, the cost of that process has been brought down to millions of dollars, which is a realm that the federal government can provide funding for.”

NIAID awarded a total of $577 million in 2022 toward the creation of nine AViDD Centers, which collectively work to discover better treatments for SARS-CoV-2 and other coronaviruses, as well as six other pathogen families of concern, which include Ebola, Zika, and other cold-causing viruses. Mount Sinai researchers received a total of $16 million and are involved in four of the nine centers.

Progress
Cut Short

Dr. White handling cell cultures stored in a cold storage unit in his lab.

The AViDD Centers were conceived as a five-year project. However, in March 2025—three years into the Centers’ inception—the Centers for Disease Control and Prevention canceled more than $11 billion in funding earmarked for pandemic response.

This included funding for the AViDD Centers, where researchers had the remainder of their unspent budget terminated immediately, pulling out the rug from under several projects.

“I’ve had to let people go from my lab, and we’re currently working in an unfunded state for the AViDD project,” said Dr. White. “We’re only continuing because we had prepaid for certain things before the funding cutoff.”

The most advanced drug developed thus far was basically a better Paxlovid for targeting coronaviruses, but without the need for the ritonavir component, said Dr. White. This is critical because the ritonavir component severely limits the use of Paxlovid in some patients due to drug interactions with other drugs. That compound is more or less ready for a pharmaceutical company to take over for clinical trial testing, with its patents remaining open access, as directed by the NIH.

“We have an excellent coronavirus drug ready to go to clinical trials, but every other drug for the other viruses—paramyxovirus, filovirus, flavivirus, and more—none of them are even close,” he said.

At best, work on the other viruses are close to getting their animal model efficacy data, which is crucial for moving the drugs into human models, said Dr. White. “Getting animal model data is hard enough in five years. Without funding for the remaining two years, getting that data in just three years is almost impossible.”

The drug dispensing robotics system, operated by research associate Mr. Benjamin in this photo, is part of the workflow in which the lab tests new antiviral compounds, said Dr. White. The equipment functions similar to an inkjet printer, and is able to print drugs into a plate format.
Dr. White’s lab had been working on animal models of coronaviruses, flaviviruses, and enteroviruses, and with funding for AViDD Centers abrupted halted, cultures remain in cold storage, waiting for work to resume.
Mr. Benjamin is monitoring the high throughput liquid handler system, which increases the number of samples that can be tested. Throughput is what drives drug discovery, and the lab was able install the equipment thanks to AViDD Centers funding, said Dr. White.

Operating costs for AViDD projects are on a larger scale because they involve high-throughput structural biology and biochemistry that run millions of dollars per year, noted Dr. White. Researchers are reaching out for patchwork funding to keep operations going, including from the Department of Defense, NIH, not-for-profit organizations such as the Drugs for Neglected Diseases initiative, and philanthropy.

Getting continued funding is crucial because viral outbreaks do not take breaks.

“At our labs, we’ve been focusing on Zika virus disease and dengue fever, and these are viral infections we’ve already seen on our shores but still have no treatments for,” said Dr. White.

“At the end of the day, I want to be able to keep my dad and many other people like him safe when—and not if—the next viral outbreak occurs,” said Dr. White. “We were already caught by surprise once with COVID-19. Let’s not have history repeat itself again.”

What You Need to Know Right Now About Legionnaires’ Disease in New York City

Updated on Jul 12, 2026 | Featured, Infectious Diseases, Your Health

You have probably heard about an outbreak of Legionnaires’ disease in New York City.  Legionnaires’ disease is a type of pneumonia (lung infection) caused by Legionella bacteria. The outbreak is mostly affecting people in the Carnegie Hill and Yorkville neighborhoods of Manhattan’s Upper East Side. The disease is suspected to have been caused by a building’s cooling system.

A key takeaway for New Yorkers is that Legionnaires’ disease is not contagious, cannot be spread by person-to-person contact, and can be treated with antibiotics, according to Vani George, DO, Assistant Professor, Medicine (Infectious Diseases), Icahn School of Medicine at Mount Sinai.

Get the latest update on the current outbreak from the New York City Department of Health.

In this Q&A, Dr. George discusses Legionnaires’ and how to protect yourself.

Can I catch Legionnaires’ from another person?

No, you cannot. Legionella bacteria thrive in warm water and people get infected and sick by breathing aerosolized water droplets in the air that are contaminated with Legionella.

Vani George, DO

What are early symptoms I should watch for, and how serious can it get?

Some of the early symptoms of Legionnaires’ disease are very similar to flu and can include fever, cough, headaches, shortness of breath, and muscle aches. As opposed to other types of pneumonia, Legionnaires’ disease can cause gastrointestinal disturbances, such as nausea, vomiting and diarrhea, as well as kidney injury.

How is Legionnaires’ disease treated?

Legionnaires’ disease can be effectively treated with antibiotics. Complications from the disease are less common if treatment is started early on. It’s important to contact your health care provider as soon as possible if you have flu-like symptoms.

How did the recent outbreak in New York City happen?

Currently, there is a cluster of Legionnaires’ disease in Carnegie Hill and Yorkville from the following zip codes: 10028, 10128, and 10075. The suspected source of the bacteria causing pneumonia in this community is a cooling tower in the affected area. Cooling towers are water systems on top of the buildings that control the temperature of cooling systems, such as central air conditioning or refrigeration. There is an ongoing investigation and all the cooling towers in this area are being tested by local health authorities. The New York City Department of Health & Mental Hygiene has reported that the current outbreak is unrelated to any building’s plumbing system. It is safe for you to drink water, bathe, shower, cook, and use your air conditioner.

Is this contamination likely to happen at other locations in the city, and how?

The contamination can happen at other locations in the summer months because the bacteria thrive in warm water between 77-113o F and in stagnant water. New York City’s cooling tower regulations have specific requirements of maintenance to prevent such outbreaks in the community.

Beside cooling towers, how else is the disease spread?

In addition to cooling towers, other sources of legionella have been decorative fountains, hot tubs, humidifiers, hot water tanks, and whirlpool spas.

Am I at higher risk because of my age or any health issues I have?

Most healthy people exposed to Legionella generally don’t get sick. Individuals at higher risk of developing Legionnaires’ disease after exposure are:

  • Adults 50 years or older
  • Current or former smokers
  • People with weakened immune systems
  • People with a chronic disease

How can I avoid Legionnaires’ disease?

If you own any of the following devices, you should follow the manufacturer’s instructions regarding cleaning, disinfecting, and maintenance:

  • Cooling towers
  • Decorative fountains
  • Hot tubs
  • Centrally installed mister, atomizers, air washers or humidifiers

The Centers for Disease Control and Prevention has developed a useful toolkit in controlling Legionella in common sources of exposure.

For more information, read Cooling Towers: Learning from Legionnaires’ Disease Outbreak Investigations from NYC Health.

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A Message Board of COVID-19 Reflections

Updated on Jun 17, 2025 | COVID-19 Reflections

Five years have passed since the height of the COVID-19 pandemic in New York City, and the Mount Sinai Health System marked the occasion by preparing ways to reflect on lessons learned during the health crisis, and to memorialize the challenges faced.

During the period in which the message board was open to Mount Sinai staff for posting, many shared their experiences of going through the height of the pandemic, such as this post from Sean Liu, MD, PhD, Medical Director of the COVID Clinical Trials Unit.

One such effort was creating a message board and inviting staff across Mount Sinai to share their thoughts. From March through June 2025, doctors, nurses, volunteers, and even researchers posted about their experiences on navigating the pandemic.

“Many of us look back at the COVID-19 pandemic like a time of war,” wrote Sean Liu, MD, PhD, Medical Director of the COVID Clinical Trials Unit, on the message board. “Our loved ones were sheltered away at home while we marched into the hospital every day to face uncertainty and witness the horror and devastation of an invisible enemy.”

Some shared memorials for lives lost to COVID-19. Some put up pictures about the camaraderie and courage shown by members on the front line. One poster, in particular, shared how he tried to lighten mood for his team with a comically sized fake mustache on his mask.

The message board is now closed for any new posts, but you may still view it to see what Mount Sinai staff shared.

Check out the message board here