Israel lives with constant military threats. Lately we are dealing with an invisible threat, the polio virus, which has crossed our borders via Egypt. Polio was supposed to have been eliminated by now, through aggressive vaccination. One of the most dangerous strains is already extinct. But partly because of conspiracy theories (in Pakistan, health workers were killed because vaccines are considered a Western attempt at fertility control), polio is still active in a handful of countries. The Global Polio Eradication project lists polio as endemic in Afghanistan and Pakistan. (Update August 2016: Nigeria was taken off the list since this blog post was first published.) Importation countries, where the virus commonly erupts, include about ten countries throughout Africa like Chad, Niger, and Somalia. Israel may well join this infamous list.
Before I address parents’ concerns, let’s start with the definitions:
IPV= Inactivated Polio Vaccine. This vaccine is made from 3 strains of the wild virus that are killed with a form of formaldehyde and is usually given through intramuscular injection. According to polioeradication.org:
The inactivated polio vaccine produces antibodies in the blood to all three types of poliovirus. In the event of infection, these antibodies prevent the spread of the virus to the central nervous system and protect against paralysis.
All children in Israel receive a series of IPV injections beginning at 2 months of age. After the regular schedule of 3 doses, individuals gain 99% immunity.
OPV= Oral Polio Vaccine. This vaccine is made from live weakened forms of the virus and is given orally in drops. Also from polioeradication.org:
OPV produces antibodies in the blood to all three types of poliovirus. In the event of infection, these antibodies protect against paralysis by preventing the spread of wild poliovirus to the nervous system. OPV also produces a local, mucosal immune response in the mucous membrane of the intestines.
In the event of infection, these mucosal antibodies limit the replication of the wild poliovirus inside the intestine. This intestinal immune response to OPV is thought to be the main reason why mass campaigns with OPV can rapidly stop person-to-person transmission of wild poliovirus.
All children in Israel born between 1990 and 2004 received several doses of OPV. In the US, it was used until 2000. Because of the slight risk of contracting Vaccine Associated Polio Paralysis, it is not used in countries where this is no active threat of wild polio. This has been the case here from 2004 until recently.
WPV= Wild Polio Virus, the active form of the virus that has been found in the sewage in the south and center of the country, as far north as Baka al-Jarbiya.
VAPP= Vaccine Associated Polio Paralysis. This is the reason for not using the OPV in countries without a polio threat. In a tiny number of cases in particular conditions, the OPV has led to a child getting a full-blown case of polio. According to the CDC:
Until recently, the benefits of OPV use (i.e. intestinal immunity, secondary spread) outweighed the risk for vaccine-associated paralytic poliomyelitis (VAPP) which occurred in one child out of every 2.4 million OPV doses distributed. To eliminate the risk of vaccine-associated paralytic poliomyelitis (VAPP), as of January 1, 2000, OPV was no longer recommended for routine immunization in the United States. [Ed.: Israel stopped giving OPV as part of routine immunizations in January 2004].
First a little history. The last two polio outbreaks occurred in Israel in the 1980’s. From 1983-1987, 8 people came down with polio. Half of the cases were associated with the OPV, but the situation was different then: The OPV was given to children who did not have the IPV first. In 1988, 15 people became seriously ill. These people contracted the disease not from the vaccine, but from the WPV–the wild virus that was circulating throughout the country. Those patients had either been unvaccinated or had only received the IPV. The country held a massive campaign to give the OPV to everyone under 40, thus ending the outbreak.
The situation today is nearly identical to the situation in 1988: A lot of children protected only by the IPV, the WPV circulating and spreading, and a fear of polio for those who cannot be vaccinated because of immunological issues. The 1988 outbreak led to the reintroduction of the OPV for all children. From 1990-2004, all children received both the IPV and the OPV. On page 10 of my 9-year-old’s vaccination folder, reproduced above, it clearly shows that she received the oral drops.
In 2004, after years of monitoring, it was felt that it would be safe to stop the OPV because the WPV was no longer a threat. But the health ministry has been monitoring the sewage. Earlier this year, the virus was found in Egypt, which quickly stepped up with its vaccination campaign. An article in Yediot Acharonot claimed that at that point, Israel should have already begun to act. But only once the virus was found in sewage in Rahat, a Beduin town in the south, did the ministry began filling the holes and making sure that all children were up to date with the IPV. Later still, after consultation with the World Health Organization, it decided that the OPV was also warranted for all children in Israel who have not received it. This generally means children born in 2004 and later. If you are not sure if your child received it, you can check your vaccination book or ask at Tipat Halav (well-baby clinic).
Since there has been so much talk about the risk of the OPV, let’s review the risk of contracting polio:
Most infected people (90%) have no symptoms or very mild symptoms and usually go unrecognized. In others, initial symptoms include fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs.
Acute flaccid paralysis (AFP)
One in 200 infections leads to irreversible paralysis, usually in the legs. This is caused by the virus entering the blood stream and invading the central nervous system. As it multiplies, the virus destroys the nerve cells that activate muscles. The affected muscles are no longer functional and the limb becomes floppy and lifeless – a condition known as acute flaccid paralysis (AFP).
All cases of acute flaccid paralysis (AFP) among children under fifteen years of age are reported and tested for poliovirus within 48 hours of onset.
More extensive paralysis, involving the trunk and muscles of the thorax and abdomen, can result in quadriplegia. In the most severe cases (bulbar polio), poliovirus attacks the nerve cells of the brain stem, reducing breathing capacity and causing difficulty in swallowing and speaking. Among those paralysed, 5% to 10% die when their breathing muscles become immobilized.
Around 40% of people who survive paralytic polio may develop additional symptoms 15–40 years after the original illness. These symptoms – called post-polio syndrome – include new progressive muscle weakness, severe fatigue and pain in the muscles and joints.
I can’t possibly answer all of the questions that have been raised about the vaccine. Most have been pulled out of the air and have no basis in reality. They come from the agenda of the anti-vaccination movement, and they waste the time of medical professionals who must spend additional time convincing parents of what should be obvious. Anti-vaccination groups have succeeded in sowing doubt among educated and rational parents, leading them to consider not vaccinating at all and in this case, refusing to participate in the current campaign that is meant to prevent a full-blown epidemic.
This is the most salient fact and it cannot be emphasized enough: The risk of a polio epidemic is real. Forty-two children have been found to be carrying the virus in their gut. So far the IPV has prevented any children from getting the disease, and carriers are symptom-free. But only the OPV can prevent them from becoming carriers of the wild virus. Unfortunately, the ministry at first only related to the risk of the unvaccinated population- which mainly includes immunosuppressed cancer/autoimmune disease patients.
Children are protected fairly well by the IPV injections they received at their regular Tipat Chalav appointments. Why get the OPV for our kids just so they won’t become carriers? Most of us don’t have loved ones who are undergoing chemotherapy or are otherwise immuno-suppressed. But the OPV helps prevent the virus from spreading, and apparently people feel that as long as their children aren’t at risk, a polio epidemic isn’t such a bad thing.
“Question: My young children have been vaccinated against polio. Why do they need to be vaccinated again? Answer: The vaccine is intended to provide additional protection to your children and to the entire extended family.”
While the ministry maintained that the vaccine was not necessary for the children who have received the IPV, parents thought they could avoid the small risk of the OPV by refusing to participate in the current vaccine campaign. Why take a risk to help prevent spread the vaccine among the unvaccinated, whether they don’t vaccinate for medical or ideological reasons? Haaretz even claimed that there was an ethical issue with vaccinating people who are immune, purely for the sake of public health. But the fact is that children are better protected from polio with the IPV and the OPV than with the IPV alone. Children who have only had the IPV are also at risk in case of an epidemic. The IPV will generally protect children, but only as long as their immune system is strong. The IPV won’t help children exposed to the WPV when they are being treated with steroids (not uncommon) or undergoing chemotherapy. Your children might be healthy now, but would you want to take a risk that they will stay that way? Also, the vaccine is about 99% effective. That sounds great, but not if your child is the one in 100 for whom the IPV doesn’t take.
Let’s address a couple of arguments against the vaccine.
- We have good hygiene in Israel. Polio is spread via contact with feces, so washing your hands will help a lot. However, the virus has still spread to 42 people (as carriers, but it counts). Are you willing to rely on everyone else’s good hygiene to prevent such a serious disease? Do you trust the store assistant who handles your produce, or the child playing with yours in the park?
- The vaccine has not been tested. It’s true that there was no clinical trial of the Glaxo-Smith-Kline version of the bivalent OPV. But that is not a reason to panic. The WHO relied on trials done by the previous manufacturer. The GSK version of the vaccine has been used on millions of children since 2009, with no unexpected effects. That is much more significant than a clinical trial on a small number of people. Are the parents concerned about “lack of testing” so careful about every medicine and food they put in their children’s mouths? For a detailed response from the WHO to the accusation of lack of clinical testing, see the letter from Suzanne Pfeiffer to Uri Goren (English excerpt below).
- The risk of spreading the virus via shedding from the OPV is higher than from the WPV. This is absolutely false, yet people state it with absolute certainty. It is based on the fact that the weakened virus is shed in the feces of children who have had the OPV recently. That is why children with a first-degree relative who is immuno-compromised will not get the OPV. Nearly every child in Israel got the OPV several times between 1990 and 2004. At the time we were warned to be careful to wash hands and double-wrap diapers, just like now. Yet not one person came down with polio via the OPV. There is no reason to think that today’s OPV is going to spread polio, when it didn’t then. In fact the risk of VAPP is significantly lower, since the most dangerous strain of the weakened virus has been removed.
- I’ll just wait and see what happens. Parents feel that it pays to take a middle ground. However, this places them firmly on the side of contributing to a polio epidemic. The virus is here now and it is spreading. Parents who wait are increasing the chances that their child will become a carrier or possibly become ill with polio. In a few weeks or months, the tide will have turned one way or the other. Maybe you (and the excellent health system we all rely on) will be lucky. Or maybe not.
- Why should I vaccinate to protect those crazy people who don’t vaccinate? It’s their problem. I see this point, except that you are doing the same as they are by relying on others to protect your child and loved ones. It’s also not the fault of the children that their parents chose not to vaccinate them. But there are many people at risk because the vaccine would be too dangerous for them, and it is the right thing to do to help protect them. The OPV also protects your own children, as I explained above.
- Even if the risk is small, why should I take it? People are upset that the health ministry has said that the risk of getting polio (VAPP) from the OPV is zero. That is not right, but it is pretty close. OPV after the IPV will prevent VAPP. In the modern era there has been only a single case of VAPP associated with the OPV, in which the child had received IPV. The cases of VAPP in India recently and in Israel (1988) and elsewhere occurred when the child received OPV without having received the IPV first. The chances are listed by the health ministry as 1 in 2.7 million, but many times that number have received the OPV throughout the world. So if your child has received the IPV and now gets the OPV, the chance of contracting VAPP are infinitely smaller than virtually every other everyday hazard you can imagine: Getting hit by a car on the sidewalk, choking on food, getting hit by a falling tree, and so on. The danger of getting sick from a full-blown wild polio epidemic with just the IPV is much greater than any risk from the OPV.
Here is an excerpt from the WHO about the “lack of testing”:
First clinical trials are required to answer well defined questions of product effectiveness, dosage and safety. The size of clinical trial matters when it comes to ability identifying post-vaccination reactions. Clinical trials will identify very common, common and uncommon reactions, i.e. those occurring up to one case in 1.000 vaccinated. Some vaccine trials have been designed to identify rare reactions, i.e. occurring app 1/10.000 vaccinated recent examples include HPV, rota virus vaccines. To identify rare events, at least 30.000 or more individuals need to be enrolled in a clinical trial. However, for very rare events these cannot be identified by a clinical trial, but by using postlicensure monitoring systems which are regular systems that monitor safety and effectiveness of products over decades and for millions of doses administered. These can trace signals for very rare events which then lead into more targeted search and specific studies. Simply, there are limits what clinical trials can produce.
Many parents are concerned about a fetus and newborns. According to the Health Ministry:
- Can children living in a household with pregnant women receive the vaccine? Children who are candidates for the live-attenuated vaccine (OPV) can receive the vaccine when there are pregnant women in the household both at the time of the vaccination and afterwards. Immunizing the older siblings will prevent their becoming infected with the wild polio virus, and therefore the infants will be protected as well.
- Can children with a sibling/siblings under the age of two months receive the vaccine? There is no need to avoid the vaccine if there are children under the age of two months in the household. Immunizing the older siblings will prevent their becoming infected with the wild polio virus, and therefore the infants will be protected as well. It is advised to maintain the personal hygiene of all the individuals living in the household by washing hands with water and soap for at least 20 seconds, in particular in the following situations: after visiting the toilet, before any contact with food, and also after changing diapers.
According to Human Virology, by L.H. Collier (2000), newborns are protected from polio by maternal antibodies until about six months. Vaccines given before then are to ensure that immunity is in place by that point.
Still not convinced? Check out these links:
- Science Blog’s debunking of Suzanne Humphries anti-vaccination video. Many people have linked to the video, which mentions Israel and polio.
- Yediot Aharonot on why Israel waited too long to start the vaccination campaign, putting public health at risk. It also contains more information than you could ever want about how the spread of the virus has been monitored. (Hebrew)
- A debunking of common arguments against reinstituting the OPV in Israel. (Hebrew: Blue are the arguments, black debunks them)
- Questions and Answers from the Health Ministry (English)
- High Court Rejects Petition to Stop Vaccine Campaign (Jerusalem Post)
- Dr. David Zlotnick on the threat and the campaign (Times of Israel)
- Dr. Keren Landsman, Israeli infectious disease specialist, debunking common arguments against the current OPV campaign. (Hebrew)
- Weizmann Institute article on the importance of the current campaign and how OPV works (Hebrew)
Thanks to reader Abbi Adest for comments, corrections, and additions, including many useful links.
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