Six new cases of polio have been reported, taking the tally to 95 across Pakistan.
The cases have been confirmed by the Sindh and KP emergency operation centres and the national coordinator for polio eradication, Dr Rana Safdar.
Of the total number of cases reported so far, nine are of VDPV2.
Two of the six new cases are of polio contracted from a mutated version of the virus in the environment. It is called vaccine-derived virus type 2 or VDPV2. They were reported from Charsadda and Torghar.
Three of the remaining cases are from Lakki Marwat, while one is from Karachi. Details of the cases were confirmed by the RRL lab.
In Lakki Marwat, the victims include a 32-month-old boy from Bakhmal Ahmadzai, a two-month-old boy from Mashamanso and another two-month-old boy from Daratang. In Karachi, the victim belongs to Jamshed Town and is a two-year-old boy.
The two cases of vaccine-derived polio were detected from two boys. One of them is three-and-a-half years old, while the other is 13 months old.
All cases are being investigated, according to the lab report.
The discovery of seven fresh polio cases in Pakistan recently prompted the government to plan vaccinations from November 18. These new cases became controversial after The Guardian published a story alleging they were covered up and that the children had caught a type of polio that had been globally finished off.
SAMAA Digital spoke to the chief epidemiologist who has been brought back to run the government’s vaccination campaigns. We asked Dr Safdar about the November 7 Guardian story and whether he agreed with its characterisation of the situation.
There are three types of Wild Polio Virus: 1, 2 and 3. Two and three have been globally eliminated, according to the WHO. But The Guardian reported that 2 had returned. Dr Safdar refuted this.
He said that the children did not contract the eliminated old type 2. More accurately, theirs were cases of polio contracted from a mutated version of the virus in the environment. They got what is called vaccine-derived polio.
This is considerably confusing, so we thought we would break down the basics.
If you have a virus you need to vaccinate people against it. The vaccination itself is made from a weak strain of the virus. You give the vaccine to children and so their body develops the immunity to it.
When we vaccinate children in Pakistan against polio, we give them the Oral Polio Vaccine (OPV) drops. This is a live but weak or attenuated form of the virus. In reaction, the children develop antibodies that protect them against active infection.
However, sometimes because the OPV is live, a child will get the drops, become immunised (and safe) but excrete a weak strain of the virus from the OPV and introduce it to the environment. This is what they call vaccine-derived polio virus or VDPV.
This kind of thing happens rarely. But just to be safe, governments keep frequently vaccinating children. However, if you leave too long a gap between campaigns, there is a risk of this happening.
In these recent seven cases, Dr Safdar says the children have VDPV. More specifically, VDPV is a mutated form of the Sabin strain of polio virus that spreads in under-immunised areas after the vaccine virus is excreted and ends up in the environment, according to the WHO.
For cases of paralysis to occur, the mutated virus needs to have been circulating in vulnerable populations for at least 12 months. This is why the WHO and Global Polio Eradication Initiative say that gaps in immunisation campaigns are the main reason why VDPV spreads.