Why vaccinate?

Explanations and clarifications regarding the polio vaccination campaign by: Prof. Johnny Gershoni (immunization expert) • Prof. Eran Bacharach (virus research expert)*

1. Sleep with the enemy: A virulent polio virus (that is, a disease agent) is passing among us - here and now. The virus will not go away by itself. No one is to blame for that. This is nature's way. If we leave the situation as it is and do nothing, the virus will continue to spread and multiply to the point where disease will appear - many will become paralyzed and some will even die from polio. This is the difficult and predictable scenario with which we are obliged to deal.

2. The polio virus and polio: The virulent poliovirus is an intestinal virus. It penetrates into the cells of our intestines, and in every cell that the virulent virus penetrates, tens of thousands of new virulent polio viruses are created, which will be excreted into the environment in the feces. When sanitary conditions are not observed, these viruses will infect more people and these people in turn may continue the cycle of infection. The virus cannot multiply outside the cells of our body. That is, the reproduction and spread of the virus is absolutely dependent on its ability to infect people. Stopping the spread of the virus requires, therefore, that we stop the cycle of infection. Only a small percentage of the infections will cause polio in an unvaccinated person, and most of the infected are not at all aware of the fact that they are spreading the violent and dangerous virus - these people are "carriers" of the violent polio virus. It should be remembered that despite the name of the disease, paralysis is not limited to children only, and even family members or elderly neighbors may become paralyzed as a result of being infected with the virus.

3. Not every vaccine prevents infection: Yunus Salk developed the vaccine shot based on killed polio virus (IPV), which was approved for use in 1955. This vaccine protects the nervous system and thus prevents polio. But the killed vaccine does not prevent the penetration and reproduction of the virulent virus in the intestine of the vaccinated person. As a result, the virulent virus will not cause disease in the vaccine, but will continue to be released into the environment. That is, the inactivated vaccine protects people from illness, but does not prevent infection with the herpes virus and its spread.
In 1963, a vaccine (called OPV) developed by Albert Sabin, based on a "live-attenuated" polio virus, was approved for use. This vaccine contains three types of live-attenuated polioviruses (virus strains 1, 2 and 3). A live-attenuated virus infects cells, reproduces in them and is even distributed in the environment but does not cause disease. That is, this vaccine, given orally, in two drops, infects the intestinal cells and triggers an immune response in the intestine itself. The weakened immune system creates protection in the body (including protection of the nervous system) against the virulent virus. Also, the weakened immune system creates a "protective wall" in the intestine against future infection with the virulent virus and thus inhibits its spread. In short: the weakened vaccine inhibits the spread of the virulent virus among the vaccinated population. It is worth noting that after a while, the vaccinated person destroys and removes the weakened virus from his body.
Metaphorically, the inactivated vaccine is likened to installing a safe in the house to protect jewelry and money. But the safe will not prevent burglars from entering the house and causing various damages. On the other hand, the weakened immunity is similar to installing a steel door that provides an additional line of defense and prevents burglars from entering the house. Any security expert will tell you that it is better not to rely on a single line of defense, and that it is better to back it up - at least - with a second, additional line.

4. How did we get into this situation? Since the early 60s, the attenuated vaccine was the only vaccine used in Israel and the USA. Although the attenuated vaccine is very safe, there is a small chance (1 in 2.4 million vaccines) that the live attenuated vaccine virus will become virulent and cause disease. This rare phenomenon may occur in people who did not receive an inactivated vaccine, prior to the administration of the weakened vaccine. In order to reduce the danger to almost zero, in 1990 Israel began to use a combined vaccine in which the weakened vaccine is given only after the administration of at least one dose of a killed vaccine. In this way, protection was created for both the nervous system and the intestine, while eliminating the rare risk of developing a disease following the administration of only a weakened vaccine. In 2004, Israel was declared free of virulent polio viruses and it was decided to stop giving the weakened vaccine and continue using only the killed vaccine. A similar decision was made earlier in the USA.
This means that all Israelis who received polio vaccines from 1963 to 2004 (more than 95%) are protected from the disease, as well as from infection. On the other hand, starting in 2004, Israeli children received only a killed vaccine and therefore, approximately one million children are indeed protected against the disease, but are not protected against infection with the violent and dangerous virus. These children are the ones who may spread throughout the population.

5. the order of the hour. The Ministry of Health decided to renew the "protective wall" in order to prevent the deadly virus from spreading throughout the country and endangering its residents. That is, we must return to the combined vaccine. In this way, the children who were previously vaccinated with only the killed vaccine will also be vaccinated with the weakened virus and as a result will also be protected from infection with the deadly virus. As mentioned, this will prevent the spread of the violent virus. For this purpose, an improved attenuated vaccine is used. This improved vaccine is identical in all its components to the original attenuated vaccine except for the fact that the live attenuated virus strain number 2 was removed from it. This is because strain number 2 has already been eradicated and there is no longer a need to vaccinate against it. This upgrade makes the enhanced attenuated vaccine more effective as it allows our bodies to focus on creating resistance to only the two existing strains of the virus. The improved vaccine has already been given to more than 2 billion people as an exclusive vaccine and has been found to be safe and effective. In fact, giving the weakened vaccine only to children who have already been vaccinated with the killed vaccine completely guarantees the safety of using the weakened vaccine. In fact, the current operation brings back the administration of the combined vaccine as it was customary between 1990 and 2004. It is worth noting that in these years no case of disease caused by the vaccine was reported.

6. "The vaccine refuser", may lead to the infection of a family member or a neighbor with a violent virus! The virulent polio virus is spread by people who have not been vaccinated with a weakened vaccine. The child protected by the killed vaccine can still be infected with the virulent polio virus and may spread it further. There is no way to avoid this possibility except by activating the additional line of defense and getting vaccinated with the weakened vaccine. It is reported that more than 95% of the population in Israel is vaccinated against polio. That is, about 5% (that is, more than 350,000) Israelis are in real danger of contracting the deadly virus and contracting polio. These are the people who were not vaccinated for reasons of a medical condition that does not allow vaccination, for reasons of ideology or for other reasons. Furthermore, every month more than 12,000 new babies are born in Israel. These babies will not receive the first (inactivated) vaccine before they are two months old, and they are in real danger of contracting the deadly virus.

To protect those who are not vaccinated and to ensure that Israel is free of polio, we must raise a double line of defense and vaccinate our children with the weakened vaccine now.

* The authors are researchers in the Department of Cell Research and Immunology at Tel Aviv University. They are not funded by any commercial company. The document was written according to the understanding of the researchers and without coordination with the Ministry of Health. The purpose of the document is to assist the general public in understanding the immediate need for the vaccination campaign against the polio virus.

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Researchers at the School of Public Health at the University of Haifa invite parents to answer a questionnaire on the issue of polio