WHO(World health organization) report on Polio in South East Asian Region

•  Amid a global shortage of injectable inactivated polio vaccines (IPV), a new inoculation regimen, employed by governments in the South-East Asian region, involving two fractional vaccine doses – each about a fifth of a full dose – provides the same level of protection against all polioviruses as does one full dose.
• This method was first used in India in its provincial vaccination programmes in early 2016 and is now being scaled up nationally. Sri Lanka and Bangladesh have also decided to introduce the fractional IPV doses this year, and other countries in the region are considering a shift in their immunization routines.
• The first of the two fractional doses is administered to infants at the age of six weeks, followed by the second at the age of 14 weeks.
• According to WHO, South-East Asia is also its first region to complete the polio vaccine switch from the traditionally used trivalent oral polio vaccine (tOPV) to the bivalent vaccine (bOPV) to prevent any paralysis caused by type 2 poliovirus strain in tOPV.
• The crippling and highly infectious disease, polio (poliomyelitis), is caused by the poliovirus and the last case of wild poliovirus in the region was recorded on 13 January 2011.
• WHO certified the region (comprising Bangladesh, Bhutan, Democratic People's Republic of Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste) as polio-free in March 2014.

About IPV:

• IPV was developed in 1955 by Dr. Jonas Salk. IPV is delivered via injection.
• IPV is produced from wild-type poliovirus strains of each serotype that have been inactivated (killed) with formalin. As an injectable vaccine, it can be administered alone or in combination with other vaccines.
• IPV provides serum immunity to all three types of poliovirus, resulting in protection against paralytic poliomyelitis.
• IPV is an evidence-based intervention that not only ensures continued protection of children against all types of polio viruses, but also helps save vaccine — a move bound to positively impact global vaccine supply in the coming years.

Advantages of IPV:

• IPV can effectively protect individual children against paralysis after three doses with a protection rate of nearly 100 percent.
• It does not cause VAPP because the vaccine consists of killed poliovirus.
• IPV can be combined with other injectable vaccines (such as DTP and Hib) to reduce the cost of administration and increase immunization coverage.

Disadvantages of IPV:

• IPV only induces serum immunity, not intestinal immunity. Thus, IPV vaccination can effectively protect the vaccinated individuals against paralysis, but does not readily protect all of them against infection with the wild virus. If vaccinated children are infected, they can become a source of infection by wild virus if their antibody levels are not high enough to stop virus excretion.
• The cost of IPV vaccination is higher than OPV because its price is higher and it requires injections by trained health workers.
• Wild poliovirus could escape from the production process.
• There is a risk of unsafe injections, which can lead to transmission of blood-borne diseases.

By: Vishal