Mini Kamboj, MSK's Chief Medical Epidemiologist
Polio has been in the news after the poliovirus was detected in wastewater samples of several New York counties — including New York City — and a person was identified as having the disease by New York health officials in July. On September 9, Gov. Kathy Hochul declared a state of emergency in New York State to help curb the spread of the virus.
Mini Kamboj, Chief Medical Epidemiologist at Memorial Sloan Kettering Cancer Center (MSK), answers questions you may have about polio, the current outbreak, and how to best protect yourself.
What is polio, and how is it spread?
Polio is a life-threatening disease caused by the poliovirus. Polio can affect the nervous system, causing muscle weakness and even paralysis. The virus spreads from person to person through contact with fecal secretions primarily but also can spread through oral and respiratory secretions. Polio is highly contagious and infected people can transmit the virus even if they aren’t sick. Polio has been virtually nonexistent in the United States since 1979, thanks to a widespread vaccination campaign.
How many cases of polio have been detected in New York State?
As of August 9, 2022, one case has been found in an unvaccinated adult in Rockland County who suffered paralysis. But Mary Bassett, the state’s Health Commissioner, warned in a statement that the single case may be the “tip of the iceberg.”
On September 9, Gov. Hochul declared a state of emergency in New York State, after health authorities announced the poliovirus was detected in wastewater samples taken in Nassau County. This follows earlier reports that the virus was found in wastewater samples taken in New York City, as well as Orange, Sullivan, and Rockland counties.
Based on earlier outbreaks, for every polio case in which a person suffered paralysis, hundreds of other people may be infected with no or mild symptoms resembling the flu or gastrointestinal illness. Of infected people who feel sick, 1 in 200 can develop life-threatening paralysis.
What does a state of emergency mean?
A state of emergency expands the network of providers who can administer the polio vaccine; they include emergency service workers, midwives, and pharmacists. The order also requires healthcare providers in New York to share polio immunization data with the state health department to help focus vaccination efforts where they are most needed.
What are the symptoms of polio?
According to The Centers for Disease Control and Prevention (CDC), most people who get infected (about 3 out of 4) will not have any visible symptoms. About 1 out of 4 people who are infected with polio will have symptoms that may include:
- Sore throat
- Fever
- Tiredness
- Nausea
- Headache
- Stomach pain
A few people (about 1 to 5 out of 1,000) will develop more serious symptoms that affect the brain and spinal cord. The most severe symptoms include muscle weakness or even paralysis. Between 2 and 10 out of 100 people who have paralysis from the poliovirus die because the infection affects the muscles that help them breathe.
What do authorities say is the cause of the recent increase in detection of the virus?
Officials continue to investigate the origin and spread of the virus. From what we know as of August 9, 2022, the New York State Department of Health says the patient was infected in the United States. This person’s illness was caused by the strain of the virus used in the oral polio vaccine, which the U.S. stopped using in 2000. Therefore, experts think the infection was introduced to New York from a region outside the United States and spread to other people in areas with low protection from vaccines.
How serious is the polio outbreak in New York?
Polio is very contagious, and someone can transmit the virus even if they aren’t sick. An infected person may not have symptoms, or their symptoms may be mild and take 30 days to appear. During this time, an infected person can unknowingly spread the virus to many others. Health officials are very concerned, especially following the identification of the case that caused paralysis, the most dreaded complication of polio. They have issued an urgent call for the unvaccinated or those who are not up to date on their polio immunization to get inoculated against the virus, citing new evidence of possible “community spread.”
What type of polio vaccine is administered in the U.S.?
The only polio vaccine approved in the U.S. is an inactivated polio vaccine (IPV), which is given by a shot in the arm or leg, depending on the person’s age.
People vaccinated with the oral polio vaccine can shed the weakened virus in their stool, and — in rare cases — this virus can change back to its original form and cause paralysis. It is important to remember that the polio vaccine used in the U.S. contains an inactivated form of the virus that cannot cause paralytic polio.
How can I protect myself against infection by the poliovirus?
Vaccination is the best way to guard against polio. Children, adolescents, and adults who are unvaccinated or do not know if they were vaccinated are at risk for polio, if exposed, and should get vaccinated.
At this time, New York city and state health officials are not recommending boosters for the general public — including people undergoing cancer treatment — who are considered fully immunized against the virus.
People undergoing cancer treatment should ensure that everyone in their household (adults and children) are fully vaccinated or up to date on their shots against the poliovirus.
The polio vaccine is part of the recommended childhood vaccines in the U.S. The CDC recommends that all children get 4 doses of the inactivated polio vaccine by age 6. Please visit the website below to learn about where people of all ages can get vaccinated:
How can I check if I’ve been vaccinated against polio?
If you are unsure whether you have been vaccinated against polio, please contact your primary care doctor, pediatrician, and/or family member for your childhood vaccination records. If you attended childcare or public school in the United States, you would have had to submit these records unless you were granted a religious exemption.
If you are not fully vaccinated against the virus, we strongly urge you to complete the polio vaccination series as soon as possible.
What should I do if I am not fully vaccinated against polio?
If you have received 1 or 2 doses only, please do not wait to complete the series now with the additional required doses, as vaccination is the best way to guard against the poliovirus. There is no need to repeat the previous doses regardless of the time passed.
Please visit the website below to learn about where people of all ages can get vaccinated
Is the polio vaccine safe for children and pregnant women?
Vaccination is the best protection against polio and is recommended for all infants and children. The CDC recommends that children get four doses of the polio vaccine by age 6. They should get one dose at each of the following ages: 2 months old, 4 months old, 6 through 18 months old, and 4 through 6 years old.
At MSK, most children who have undergone treatment for cancer receive their polio shots again 3 to 6 months after their treatment was complete, regardless of previous vaccination.
The IPV is very safe and effective and provides nearly complete protection from paralytic polio. The vaccine does not have significant side effects, except for rare cases of allergic reactions, which can occur with any immunization or medication. Some people may experience soreness or redness at the injection site.
Those with severe allergies to certain components of the IPV, including neomycin, streptomycin, or polymyxin B, should not receive the vaccine. It is best to wait if you are suffering from an acute illness until you fully recover before getting the IPV.
The polio vaccine can be given during pregnancy and is recommended if the individual is at risk of exposure to the virus. Pregnant persons should discuss the risks and benefits of IPV with their healthcare provider.
Are cancer patients vulnerable to polio, even if they were vaccinated against the virus when they were children?
Generally, polio vaccination as a child provides long-term protection. Routine re-immunization after common cancer treatments, including surgery, chemotherapy, radiation, or immunotherapy, is not recommended for adults. In certain situations — such as after a stem cell transplant or for children who have completed their cancer treatment — people may lose vaccine protection and need to be re-immunized against polio. Public health authorities also may advise a booster shot for cancer patients based on their risk of exposure to the virus.
Cancer patients should ensure they have received all their polio shots (a total of four doses) as a child. They should receive a booster if they are unsure or live in a community with current evidence of transmission.
In response to the current situation, booster shots are recommended only for fully immunized people who will or might have close contact with a person known or suspected to be infected with poliovirus or such person’s household members or other close contacts.
Patients also should confirm they are up to date on their vaccines before traveling to specific destinations outside the U.S.
What is a polio booster shot, and who should get one?
A booster is a single dose of the inactivated polio vaccine (IPV) and is administered to anyone who was fully vaccinated (received all four doses) previously.
Most people who are fully vaccinated against the poliovirus do not need a booster unless there is an outbreak of polio in their community. In response to the current situation, booster shots are recommended only for fully individuals who will or might have close contact with a person known or suspected to be infected with poliovirus or such person’s household members or other close contacts. This is especially important if you live, work, or attend school in an area where poliovirus has been detected: Rockland, Orange, New York, Sullivan, and Nassau counties.
Other reasons when a polio booster may be considered are:
- extended travel to certain destinations outside the U.S.
- healthcare workers who are exposed to suspected or confirmed polio cases or handle their specimens.
- individuals with occupational exposure to wastewater
- working with the poliovirus in a lab
At this time, New York city and state health officials are not recommending boosters for the general public — including persons undergoing cancer treatment — who are considered fully immunized against the virus. People undergoing cancer treatment should ensure anyone they come in contact with, including their loved ones (adults and children), is fully vaccinated against the poliovirus.
I am fully immunized against polio. What additional precautions should I take to protect myself from the virus?
At MSK, employees must always follow standard precautions when caring for patients. Immunized employees who follow standard infection control precautions have an extremely low risk of acquiring polio in the healthcare setting. A reminder that practicing frequent hand hygiene reduces the risk of healthcare-associated infections and that everyone must continue wearing masks in our clinical buildings.
Is polio curable?
There is no cure for paralytic polio, but it is preventable through vaccines, which are safe and effective. Polio vaccines have been used since the 1950s and have worked to eliminate poliovirus in the United States for more than 30 years.
