A child getting an injectable vaccine. Right; a child receives an oral polio vaccine. Uganda is switching to injectable polio vaccine because it offers life-long protection for children.
In Summary
Oral polio virus is the most common type of vaccination against the disease world over. However, in Uganda, it has been found prudent to switch to the injectable form.
Uganda is joining 47 other countries in Africa and 155 countries worldwide to switch from the oral polio vaccine to an injectable vaccine in a bid to eliminate polio by 2018.
This means that instead of the four shots of oral polio vaccine that children used to get from the age of two months, they will now get one injection of the virus that will protect them for a life time.
Dr Annet Kisakye, the team leader of the extended programme on immunisation at World Health Organisation, Uganda office says Oral Polio Vaccine (OPV) contains live, weakened particles of all three strains of the wild poliovirus which helps a child develop an immune response in their gut once they are injected with the virus.
“OPV is effective in stopping outbreaks because children who have been immunised do not further transmit the wild virus through the community. As such, OPV is the primary tool used to stop wild polio,” Dr Kisakye explains.
She adds that unlike OPV, the injectable polio vaccine (IPV) does not contain the weakened particles of poliovirus; the strains of wild polio are existent in the vaccine but they are not activated.
“The inactivated polio virus is administered by injection and contains inactivated particles of the polio virus. It cannot cause virus derived polio, but isn’t as effective in stopping outbreaks,” she continues.
The difference
Dr Stuart Musisi, the Masaka District health officer says the current oral polio vaccine creates immunity in the gut unlike the new inactivated polio vaccine which will create immunity in the bloodstream. He added that IPV, also known as inactivated polio vaccine, is a life-long prevention approach against polio in children which will be administered once to all children below five years.
“As a first step in this process, the polio programme will withdraw the trivalent oral polio vaccine (tOPV) and replace it with the bivalent oral polio vaccine (bOPV) in routine immunisation systems around the world. Over the next two weeks, 155 countries around the world will withdraw tOPV from their routine immunisation systems and replace it with bOPV,” Dr Kisakye adds.
Administering the injection
To administer the vaccine, an injection in the leg or arm, depending on the patient’s age will be given. It can be given at the same time as other vaccines.
Dr Kisakye adds that once all wild polio is eradicated, all OPV will be withdrawn and replaced by IPV. At the moment, Pakistan and Afghanistan are the only countries in the world still reporting cases of wild polio.
Polio cases have been reducing steadily since 1988. Dr Kisakye explains that the reduction rate is at 99.9 per cent.
In addition, Africa has been polio free since August 2015. The change is part of a worldwide movement which will see 155 countries engage in a two week campaign to make the switch from OPV to IPV.
“The combination of IPV and OPV provides stronger protection in children against polio. IPV strengthens immunity in the blood while OPV strengthens immunity in the gut. The IPV which is administered by injection will be introduced into routine immunisation programmes in more than 100 countries worldwide by July 2016,” Edmond Mwebembezi, the spokesperson of WHO explains.
The scientific rationale for IPV introduction and OPV withdrawal paper by WHO states that IPV will see a minimizing of the risk of attaining type two of vaccine derived poliovirus cases and vaccine-associated paralytic poliomyelitis which causes a child to get paralysed when they receive their dose of OPV.
One in 2.7 million children receiving their first dose of oral polio vaccine will get paralysed while only 33 cases have been documented worldwide for vaccine derived polio viruses.
“IPV is less effective than OPV in inducing intestinal mucosal immunity among previously unvaccinated individuals. Children given IPV then challenged with OPV become infected and shed OPV in their faeces. Nonetheless, IPV can reduce the quantity and duration of virus shedding in stool samples, which may contribute to a reduction in transmission. It has been suggested that IPV may have a greater impact on oropharyngeal shedding but there is limited evidence to support this observation,” the WHO paper reads in part.
An online medical and vaccine report states that Uganda remains in the “wild poliovirus importation belt” which stretches from West Africa through Central Africa to the Horn of Africa. Countries along the belt are susceptible to recurrent polio virus infections originating from northern Nigeria; however, Uganda eradicated polio roughly a decade ago.
In Uganda, the vaccine was introduced last month by Sarah Opendi, the State Minister for Primary Health Care ahead of the official launch of the vaccine in the 155 countries.
Opendi says OPV will be administered alongside IPV until the latter is completely phased out at this month.
editorial@ug.nationmedia.com
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