Susceptibility of Infants to Measles

• 09 Dec 2019

Why in News

According to recent studies,infants become susceptible to measles infection at the end of three months after birth and not six months as earlier thought.

• A study observed that maternal antibodies disappear by the end of three months, contrary to the common notion that maternal antibodies against measles protect infants for the first six months of age.
• Currently, in countries like India with ongoing transmission of measles the first dose of vaccination is given only at 9-12 months of age.
  
  • In countries with no ongoing transmission, the first dose is administered when the baby is 12-15 months of age.
• Thus babies remain susceptible to measles infection for a longer period of time before they get vaccinated with the first dose.

Key Points

• Measles Burden: In 2018, measles caused an estimated 10 million cases and 1,42,000 deaths globally. Nearly 72,000 cases have been reported in India during 2018-2019 which is the third-highest in the world.
  
  • At 2.3 million, India has the second-highest number of children who are not vaccinated against measles after Nigeria.
  • But the number of unvaccinated children in India had reduced from 2.9 million (2017) to 2.3 million (2018).
• Vaccination Coverage: The World Health Organisation (WHO) recommends the high coverage [over 95%] of two doses of measles-containing vaccine to protect infants from measles.
  
  • But, in 2018, 86% of children received the first dose and only 69% received the second dose globally.
• Time for Vaccination: The vaccine-induced protection is less in infants if the vaccine is given earlier than recommended.
  
  • Also, early vaccination may "alter response" after the second dose of vaccine, leading to “lower levels of the antibody” compared with children who are vaccinated as per schedule.
  • The pregnant mothers cannot be administered measles vaccine as the vaccine uses live, weakened virus. The weakened or live virus after the injection may cause an infection in the vaccinated person’s body.
• Threshold level of Protection: In the case of India, many mothers gain immunity through natural infection and are also continually exposed to the virus, leading to "repeated immunologic boosting and more robust antibody levels".
  
  • Infants born to mothers in countries where measles virus has been eliminated have lower maternal antibodies and these antibodies quickly fall below the threshold of protection before they receive the first measles vaccination dose.
• Maternal Age: The probability of infants getting infected increases with maternal age. This is because pregnant mothers remain protected through vaccination and not through natural infection.
  
  • A one-month-old infant has a 25% probability of getting infected with measles if the mother is 25 years old but the probability increases to 40% if the mother is 40 years old.

Indian Government Initiatives

• Measles-Rubella (MR) vaccination
  
  • The Ministry of Health and Family Welfare launched MR Vaccination program in 2017.
  • The MR campaign targets around 41 crore children across the country, the largest ever in any campaign.
  • All children aged between 9 months and less than 15 years will be given a single shot of Measles-Rubella (MR) vaccination irrespective of their previous measles/rubella vaccination status or measles/rubella disease status.
  • MR vaccine will be provided free- of- cost across the states.
• Other Initiatives include Universal Immunization Programme (UIP), Mission Indradhanush and Intensified Mission Indradhanush.

Measles

• Measles virus is an enveloped, ribonucleic acid virus of the genus Morbillivirus.
• Measles is highly contagious, and an infected person often transmits the virus to over 90% of unprotected close contacts.
• The virus infects the respiratory tract, then spreads throughout the body. Measles is a human disease and is not known to occur in animals.
• Measles can be entirely prevented through a two-dose vaccine and had been officially eliminated in many countries with advanced healthcare systems.
  
  • The first dose of measles vaccine was introduced in the 1990s in India.
  • India introduced the second dose from 2010 onwards. India was one of the last countries to add a second dose of measles vaccine.
• Treatment
  
  • No specific antiviral treatment exists for measles virus.
  • Severe complications from measles can be avoided through medical care that ensures good nutrition, adequate fluid intake, and treatment of dehydration.

Source: TH