Polio virus contamination what, why, what next: an explainer

polio vaccine, polio virus contamination, polio II virus
Konnie Huq in Lucknow during the November Immunization days in Northern India..India has been engaged in a campaign to eradicate polio in India which target the high-risk area of Uttar Pradesh and Bihar with polio immunization drives every 2 months. (photo Jean-Marc Giboux)

Reports of contamination of the polio virus put India’s polio free status at stake

Contamination of over one lakh doses of polio vaccine with a polio virus variant long thought to have been eliminated, has caused a major public health panic in India. Reports suggest the contamination is serious enough to put India’s precious four year old polio free status at stake.

Medibulletin takes you through the controversy; what went wrong and what are the implications.

What has happened?

Three batches of polio vaccines, have been found to have been contaminated by the polio II virus. Some of these vaccines are suspected to have been administered to children in parts of Uttar Pradesh, Maharashtra and Telangana as the virus has been detected in the stools of some children during random checks. The contamination essentially means that a long forgotten virus has suddenly made a comeback into the public health conversation.

India eliminated wild polio II contamination in 1999 and was certified polio free in 2014

Why is that a cause for worry?

India eliminated wild polio II contamination in 1999 and was certified polio free in 2014. The cleansing of Polio II was thought to be so complete that the vaccines currently administered are not for polio II but only for the strains I and III. This means that incursion of polio II was an uncontrolled event and the amount of exposure is unknown. A vaccine by definition is something that introduces its recipients to a possible antigen but only in controlled amounts. This is to ensure that the body develops antibodies to fight the infection but does not get the disease. However when it is a contamination the amount is not controlled and can at least theoretically lead to an infection.

What action has been taken?

The vaccine is manufactured by a company called Biomed, based out of Ghaziabad. One person has already been arrested but several others are absconding. The Union health ministry has formed a three member committee to look in on the issue. The World Health Organization though has played down the risks arising out of the contamination citing the high routine polio immunisation coverage in the country.

What next?

The government has already ordered that all children who received the contaminated vaccine should be vaccinated against Polio II but it is a difficult task to trace all of them. Public health officials have to be on high alert wherever these vaccines were given.


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