A specific type of poliovirus has spread in Rockland County, New York, as well as neighboring areas, prompting the World Health Organization (WHO) to add the United States to a list of countries (opens in a new tab) where similar polioviruses have been detected. The list includes around 30 countries in Europe, Asia and Africa, including the UK, Israel, Yemen, Algeria and Niger.
Last week he announced the official addition of the US to this list US Centers for Disease Control and Prevention (opens in a new tab) (CDC) and the news raised questions about what happens next. Do people who received all doses of childhood polio vaccine now need a booster? What should you do if you are not sure of your vaccination status or if you know for sure that you have not received the polio vaccine?
Crucially, there is no blanket recommendation that fully vaccinated people seek polio boosters.
“Certainly, at this time, there has been no national or local recommendation that people who are confident about their childhood vaccination series need an additional booster,” said Dr. William Schaffner, professor of medicine in the division of infectious diseases. . at Vanderbilt University School of Medicine in Tennessee. However, he noted that there may be select circumstances, which we will detail below, in which it might be reasonable for a person to seek reinforcement.
Related: Who created the polio vaccine?
For now, health officials’ main concern is vaccinating those who have not yet completed their polio vaccination series, Schaffner told Live Science.
“Polio vaccination is the safest and best way to fight this debilitating disease and it is imperative that people in these communities who are not vaccinated are immediately updated on polio vaccination,” Dr. José R. Romero , director of the CDC National Center. for immunization and respiratory diseases, the CDC said in the statement. “We cannot stress enough that polio is a dangerous disease for which there is no cure.”
Initial polio vaccination recommendations
Since 2000, the US has used only the inactivated polio vaccine (IPV), a vaccine usually injected into the arm or leg that contains “dead” poliovirus that cannot cause disease, according to the CDC (opens in a new tab). Another type of polio vaccine, the oral polio vaccine (OPV), is just as effective, but its use was stopped in the US because it contains live but weakened poliovirus, Previously reported by Live Science. These weakened virus it can be shed in the stools of vaccinated people and, in rare cases, can evolve to behave like natural wild polioviruses capable of causing disease and potentially paralysis in unvaccinated people.
Because of this risk, the US now only administers IPV, but “vaccine-derived” polioviruses can still be imported from places that use OPV, which is exactly what happened in the current outbreak .
“It reveals how vulnerable we are to imports, not only of poliovirus, but of other viruses, germs, from abroad,” Schaffner said.
To protect against polio, the CDC recommends that US children receive four doses of IPV, with one dose given at each of the following ages: 2 months, 4 months, 6 to 18 months, and 4 to 6 years . The CDC also offers several “recovery hours” (opens in a new tab) for children who start their vaccination series late or are delayed between doses.
Adults who have never received a polio vaccine should receive three doses of IPV. These individuals can get their first dose at any time, get their second dose one to two months later, and get their third dose six to 12 months later, the CDC recommends. Adults who have received only one or two doses in the past should seek additional doses to reach the recommended three.
Most US residents complete their polio vaccine series during childhood and are generally not recommended to receive boosters later in life. “This is just a testament to the very strong, lifelong protection you get from the polio vaccine,” Schaffner said.
The first polio vaccines were available in 1955 and the vaccines have been recommended as routine vaccinations ever since, according to Verify (opens in a new tab). An adult is considered fully vaccinated if they have received at least three doses of IPV or “trivalent” OPV (tOPV), that is, OPV that protects against all three types of poliovirus, P1, P2, and P3. Alternatively, an adult is fully vaccinated if they have received four doses of any combination of IPV and tOPV, according to the CDC (opens in a new tab).
Two doses of IPV are at least 90% protective against paralytic poliomyelitis, which can occur when the virus infiltrates the central nervous system and causes weakness or paralysis in the arms, legs, or both; this can lead to permanent disability and death. Three doses are at least 99% protective, according to the CDC.
Related: Africa declared free of wild poliovirus
Who needs a polio booster?
There are cases where fully vaccinated adults may consider a one-shot polio booster.
For example, a booster is recommended if you work in a laboratory or healthcare setting where you handle poliovirus samples, or if you are a healthcare worker who treats polio patients or may interact with close contacts of people infected with the virus. . You can also seek a booster if you are traveling to a country where the risk of exposure to polio is “higher”. For example, wild poliovirus still circulates in Afghanistan and Pakistan, and long-term visitors should receive an IPV booster four weeks to a year before traveling there, according to the Global Polio Eradication Initiative (opens in a new tab). (No similar recommendation has yet been extended to the US.)
So far, only one case of paralytic polio has been detected in the US outbreak; this happened in an unvaccinated adult in Rockland County. Subsequently, poliovirus was detected in wastewater samples from Rockland County, Orange County, Sullivan County, New York, and Nassau County, the New York State Department of Health reported (opens in a new tab).
The health department currently recommends a polio booster for the following New Yorkers:
- People who will have or may have close contact with a person known or suspected to be infected with poliovirus or members of that person’s household or other close contacts.
- Health care providers who work in areas where poliovirus has been detected and may handle samples that may contain poliovirus or who treat patients who may have polio.
- People with occupational exposure to wastewater.
People from the affected counties who have weakened immune systems It might also consider a booster, said Vincent Racaniello, a poliovirus expert at Columbia University’s Vagelos College of Physicians and Surgeons, in a statement (opens in a new tab). And if you’re not sure how many doses of polio vaccine you’ve received, you can also consider getting a boost, she said.
There are some antibody tests for polio, but these are not recommended for assessing vaccination status because there is limited access to tests that detect antibodies to all three types of poliovirus, according to a 2017. Morbidity and mortality weekly report (opens in a new tab) published by the CDC. “In the absence of the availability of antibody testing to all 3 serotypes, serologic testing to assess immunity is no longer recommended,” the report states.
For US residents beyond New York, the risk of exposure to polio is probably similar to before the outbreak, Schaffner said, meaning negligible. However, people exposed to the virus in New York could get on a plane and carry polio to additional locations; for that reason, vaccination remains important no matter where you live, he said.
It’s also key to note that “although IPV is very good at preventing the more serious potential effects of the disease, people who received the vaccine could still be carriers of polio and could spread it to others,” Dr. Leana Wen, emergency physician. and Professor of Health Policy and Management at the Milken Institute School of Public Health at George Washington University CNN (opens in a new tab).
People vaccinated with IPV can still pass poliovirus in their stool if they are ever exposed to the pathogen, even though they are protected against paralysis, according to the Pan American Health Organization (opens in a new tab). This is because IPV generates a very strong force antibodies response in the blood, but is not as effective in generating immunity in the intestines.
About polio
The polio virus is most often spread by contact with the feces of an infected person; less commonly, it can be spread through respiratory droplets that are released when an infected person sneezes or coughs, according to the CDC (opens in a new tab). Frequent hand washing with soap and water can help prevent the spread of the virus; Notably, however, alcohol-based hand sanitizers do not kill polioviruses.
Most people who contract polio do not develop any visible symptoms. About 25% develop flu-like symptoms, including sore throat, fever, fatigue, stomach ache and nausea. A much smaller fraction of infected people develop serious symptoms, such as meningitis, an infection of the tissue surrounding the spinal cord and/or brain; or paralysis, which can lead to permanent disability and death.
Sometimes people who seem to recover from polio develop new muscle pain, weakness, or paralysis decades later; this is known as post-polio syndrome.
Originally published in Live Science.