More than 500 people have been hospitalized with influenza symptoms only to the city’s Botkin infection clinic since the beginning of the year, and 123 of them have swine flu.

ST PETERSBURG, January 18. /TASS/. The number of swine flu cases has grown in St Petersburg, Russia’s second largest city, a local health official said on Monday.

"The number of swine flu cases is higher than before," Tatiana Zasukhina said.

According to preliminary reports, five people died from the virus.

Earlier in January, a number of swine flu outbreaks were registered in Western Siberian cities.

Swine flu is the popular name for influenza caused by a relatively new strain of influenza virus A. It was responsible for the flu pandemic in 2009. The virus is officially known as influenza virus A/H1N1.

Swine flu is contagious, and it spreads in the same way as the seasonal flu.