Development of Polio Vaccines
Bonnie A. Maybury Okonek and Linda Morganstein, Editor
Answers for all the questions from the lesson ‘Development of Polio Vaccines’ included in the CHSE +2 book ‘Invitation to English – 1’.
Think it out – 1
1. What is poliomyelitis?
Answer – Poliomyelitis is an acute, viral, infectious disease that can cripple a person for life. It spreads through the fecal-oral route. It can ravage the life of the affected person by paralyzing him or causing his death.
2. When did Roosevelt find out that he had polio?
Answer – After a brisk outing, and some swimming, he wanted to relax and went to bed. He felt cold, and in a few days, Roosevelt concluded his symptoms unequivocally pointed to polio.
3. What are the early symptoms of polio attack?
Answer – The early symptoms are quite akin to those of flu. The patient feels headache, nausea, vomiting, and fever.
4. Which things are the carriers of poliovirus?
Answer – The virus may get embedded with droplets of water or any fluid and move around in the air. The fecal matter of a victim could be a big source of the virus.
5. What percentage of people attacked by poliovirus does actually suffer from severe polio?
Answer – Just about 10% of the infected people develop symptoms, and 1% of them could find thir limbs crippled for life through paralysis.
6. What are the two forms of polio?
Answer – The spinal form and the bulbar forms are the two variants of polio.
7. Are the symptoms of both the forms of polio similar or different? Which form of the disease is more dangerous?
Answer – The symptoms are different in the two forms. The spinal form attacks the limbs and the bulbar form attacks the lungs.
Think it out- 2
1. Did polio affect Roosevelt‘s political career?
Answer – Roosevelt took his affliction in his stride and went ahead with his political duties. Polio had very nominal effect on his career.
2. What was the highest position did Roosevelt achieve in his political career?
Answer – He rose to the most coveted position – the President of the United States of America.
3. How did he spearhead the fight against polio?
Answer – Roosevelt spread awareness about this deadly disease among the people so that they could take suitable precautions. He also set up funds for research to find a medicine that could curb polio at the very outset.
4. Who are the most vulnerable to polio?
Answer – Young children living in unsanitary environment are most likely to fall prey to polio.
5. Why were parents in the early 1950s afraid of sending their children to schools?
Answer – The parents felt sending their children to school could expose them to infection from other children.
Think it out – 3
1. Why did early attempts at the development of polio vaccine fail?
Answer – The researchers were unaware of the fact that polio virus has three strains. So, killing just one virus didn’t make a child immune to the disease.
2. Why were some children immune to polio before the 1900s?
Answer – Lack of knowledge about the importance of sanitary practices made it easy for the virus to spread and infect young children. Most of these children fought off the polio virus in the body by developing antibodies that retained its anti-polio potential the whole life. Girls with such antibodies grew up to become mothers and passed on their antibodies to the babies through breast-feeding. This natural process made some children immune to polio.
3. Did improved sanitation help to avoid polio attack before the 1900s?
Answer – Improved sanitation did go a long way in fending off infection by polio viruses.
4. How did the March of Dimes work for the elimination of polio?
Answer – Researchers, funded by March of Dimes, delved into the enigma behind polio and came out successful with a vaccine that destroyed all strains of the virus. It was a path-breaking invention.
Think it out – 4
1. What method did Jonas Salk use to develop polio vaccine?
Answer – In 1952, Salk pioneered the development of a successful vaccine using a mixture of the three types of virus, that were grown in monkey kidney cultures. He developed a process using formalin, a chemical that inactivated the whole virus.
2. How did Salk develop a successful vaccine?
Answer – The field trials with the original Salk vaccine yielded mixed results. Out of the 260 cases induced by the vaccine, there were 10 fatalities. The problem was traced to incomplete inactivation of some virus particles. This lacuna was soon addressed. Since then the vaccine has been highly effective, with a 70 – 90% protection rate.
3. How was the first polio vaccine accepted?
Answer – Large scale testing of the vaccine in clinical trials was undertaken in the United States and parts of Canada in 1954. The scope of the trials was historic and the results were spectacularly impressive. Cases of polio plummeted visibly in the vaccinated test groups. In 1955, the government granted permission for the vaccine to be distributed to the children of the country.
4. What was the problem with the original Salk vaccine?
Answer – The success rate was rather low as the death figures after the trial were high. The problem was traced to incomplete inactivation of some virus particles, which was soon corrected. Since then the vaccine has been highly effective, with a 70 – 90% protection rate.
5. How was Salk vaccine given?
Answer – The Salk vaccine is given in two intramuscular injections spaced one month apart and requires boosters every five years. Arranging the syringes and needles for a mass drive is both expensive and cumbersome.
6. What are the advantages of an oral vaccine?
Answer – It is hassle free and cheap to administer as it involves putting a few drops in the child’s mouth.
8. What is its major disadvantage?
Answer – The major disadvantage is that it, being a live virus, cannot be used for patients with compromised immune systems. It can cause disease in these patients. It also cannot be used by those in close contact with immune-compromised patients because the live virus in the vaccine can be shed in the faeces of those who ingest it. It raises the risk of further transmission. Another disadvantage of the Sabin oral vaccine is that those who have an enterovirus infection of the gastrointestinal tract when taking the oral vaccine may not develop the immune response.
Think it out – 5
1. What induces higher levels of antibody formation?
Answer – More effective culturing and purification techniques result in higher levels of antibody formation.
2. What is the latest research in development of polio vaccine?
Answer – Researchers are using Escherichia coli (a common bacterium that inhabits the gastrointestinal tract of humans) as a medium to produce more efficient polio vaccine.
3. Is complete eradication of poliomyelitis possible?
Answer – Yes, it’s possible.
Click here for answers for other lessons in the CHSE +2 2nd year syllabus.