Experts on Wednesday called out an incorrect Delhi government report that shows that two people died of smallpox and 11 of polio in the city in 2016. “It is not possible,” an unidentified Health Ministry official told the Hindustan Times. “There has to be some mistake. The last polio case in the country was in 2011 and smallpox has not been around for years.”

The Delhi government on Wednesday released its annual report on the registration of births and deaths in the Capital. The Statistics Department prepares it by compiling data from civic bodies.

Another health official told the daily that it “could be a clinical error”. This raises doubts about the credibility of these reports, as departments rely on such data to frame policies and action plans.

The World Health Organisation had declared India polio-free in 2014. Pakistan, Nigeria and Afghanistan are the only countries where the virus is still found. The last known case of smallpox was reported in Somalia in 1977, according to the United Nations.